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Application of microchip-capillary electrophoresis
and pulsed electrochemical detection to the
analysis of biologically relevant phenolic
compounds*
Maria F. Mora, Yongsheng Ding
a
, Eric Mejia, and Carlos D. García
Department of Chemistry, The University of Texas at San Antonio, San Antonio, TX, U.S.A.
a
Permanent address: Department of Chemical Biology, Peking University Health Science Center, Beijing 100083,
China
Correspondence: Dr. Carlos D. García, Department of Chemistry, The University of Texas at San Antonio, 6900
North Loop 1604 West, San Antonio, TX 78249, U.S.A.; e-mail: carlos.garcia@utsa.edu
Abstract
This paper reviews the most recent results regarding the use of microchip-capillary electrophoresis and pulsed electrochemical detection. The arti-
cle is particularly focused on the analysis of three groups of phenolic compounds: U.S. EPA contaminants,
1
antioxidants,
2
and pharmaceuticals.
3
Background information regarding the importance of these compounds, as well as a brief discussion covering other analytical strategies for the
analysis of phenols, are also included.
I
n recent years there has been a growing concern
regarding the consequences of wildlife and human
exposure to xenobiotics. A considerable number of
these compounds have a phenol-based structure.
Depending on the type and location of substituent
groups, these phenols (phenolic compounds, pheno-
lics, or mixtures of phenols) present varying biological
activities ranging from contaminants, disinfectants, her-
bicides, pharmaceuticals, antioxidants, and hormones,
to neurotransmitters.
Phenols are also the major organic constituents
found in effluents of coal conversion processes, coke
ovens, petroleum refineries, phenolic resin manufactur-
ing, herbicide manufacturing, fiberglass manufacturing,
and petrochemicals.
4–10
In general, phenolic contami-
nants are harmful in that they can produce alteration of
cell membranes, mutation of the genetic material, and
change in the speed of photosynthesis. The effect of
human exposure to phenols depends on the com-
pound, the contact time, and the contact via. In gener-
al, they can produce a wide range of symptoms and
pathologies from headaches to different cancers.
11–14
Most phenols and their derivatives can be oxi-
dized by oxygen, allowing the use of some phenolic
compounds as antioxidants.
15–18
Indeed, the most
broadly used primary synthetic antioxidants are hin-
dered phenolics, which are used in petroleum prod-
ucts,
19
rubbers,
20
soaps, plastics,
21
as well as animal and
Indexing terms
Microchip, capillary electrophoresis, pulsed amperometric detection, phenolic compounds
Abbreviations
BHT, 3,5-di-
tert
-butyl-4-hydroxytoluene; NSAIDs, nonsteroidal anti-inflammatory drugs; AP,
N
-acetyl-
p
-amino-phenol; DFS, diflunisal
(5-2’-4’-difluorophenyl salicylic acid); DCF, diclofenac (sodium
o
-2,6-dichloroanilino-phenyl acetate); APCI, atmospheric pressure
chemical ionization; PDMS, polydimethylsiloxane; EOF, electroosmotic flow; ICP-MS, inductively coupled plasma-mass spectrome-
try; ECD, electrochemical detection; PAD, pulsed amperometric detection; PDMS, poly(dimethylsiloxane); MEKC, micellar electroki-
netic chromatography; CMC, critical micelle concentration; SDS, sodium dodecyl sulfate; PG, propyl gallate; OG, octyl gallate; LG,
lauryl gallate; NDGA, nordihydroguaiaretic acid; THF, tetrahydrofuran; PCP, pentachlorophenyl; DNOC, 4,6-dinitro-
o
-cresol
*Part of the results discussed in this minireview were presented at the LACE 2005 Meeting, December 2–6, 2005, Guaruja, Brazil.
J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006 ###### J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006
vegetable products.
22
Synthetic phenolic antioxidants
have traditionally been based on 3,5-di-tert-butyl-4-
hydroxytoluene (BHT).
16,23
This functional moiety has
been incorporated into larger molecules, affording
products with lower volatility and color contribution.
24
Many cosmetic, pharmaceutical, and food processing
industries intensively use phenolic antioxidants in their
formulations,
25,26
either alone or in mixtures.
Although these antioxidants can increase a prod-
uct’s lifetime, some concerns have been raised about their
potential detrimental health effects.
27–30
Many products
also contain natural phenolic antioxidants.
31–40
Because of
the potential health benefits, special attention has been
directed to the content of resveratrol,
41–45
antho-
cyanins,
46,47
and catechins
36,48–53
in different matrices and
nutraceutical formulations.
54
Nonsteroidal anti-inflammatory drugs (NSAIDs)
are another group of biologically important phenolic
compounds that have very well-defined pharmaceutical
activities, and are among the most commonly used
over-the-counter pharmaceutical products. These com-
pounds are used as analgesics, antipyretics, antialler-
gics, and anti-inflammatory drugs. Aspirin (acetylsali-
cylic acid), acetaminophen (N-acetyl-p-amino-phenol,
AP), diflunisal (5-2’-4’-difluorophenyl salicylic acid,
DFS), and diclofenac (sodium o-2,6-dichloroanilino-
phenyl acetate, DCF) are commonly used with very lim-
ited age restrictions. However, if the dose exceeds the
therapeutic range, these compounds can produce a
large number of complications, including acidosis,
55
hepatic necrosis, and renal disorders.
56
A summary of
some of the biological activity and applications of phe-
nols is included in Figure 1.
Recent advances in the analysis of phenolic compounds
Various methods have been reported for the deter-
mination of environmentally important phenolic com-
pounds, such as GC
57
and HPLC
14,57–81
with different
detectors. Among others, Suliman et al.
59
reported the
analysis of chlorophenols in water by HPLC using
coumarin-6-sulfonyl chloride as a fluorogenic pre-
column label. Lee and Zhao
61
used liquid phase
microextraction with back extraction combined with
HPLC for the analysis of several chloro- and methylphe-
nols. Detection limits in the ng L
–1
range were obtained
by Rosenberg and Wissiack
82
using on-line solid-phase
extraction coupled to HPLC-atmospheric pressure
chemical ionization (APCI)-MS. Montero et al.
67
report-
ed the study of chlorophenols in lake and groundwater
samples using a polydimethylsiloxane (PDMS) stir bar
for the extraction of the derivatized phenols, and GC-
MS for the analysis. Vermeulen et al.
75
proposed a
derivatization step using acetic anhydride followed by
liquid–liquid extraction and GC-MS analysis. Recently,
Blythe et al.
68
reported a method with lower detection
limits (0.2 –3.1 ng/L) for bromophenols in water.
Chromatographic methods
83–86
are also usually cho-
sen for the determination of phenolic antioxidants in
food,
31,83,87–89
beverages,
90
plants,
31,32,50,89,91–96
cosmetics,
26
and clinical
14,97–99
samples. Nonchromatographic
40,46,100,101
electrochemical
16,18,22,23,102
flow-through,
16,23,103,104
and
electrophoretic
105–107
methods have also shown their util-
ity for this purpose. Numerous biosensors have been
designed for the analysis of phenols.
108–123
Phenol-
oxidases (laccases and tyrosinases) are the most com-
monly used enzymes for these devices.
124
Just to name a
few, Mailley et al. designed a biosensor based on the use
of electrogenerated polypyrrole surfaces.
116,117
More
recently, Pingarrón proposed the use of enzymes as
recognition elements for the analysis of propyl gallate.
118
Phenols with pharmaceutical activity can be analyzed by
means of immunoassays,
125,126
spectrophotometry,
127,128
thin-layer chromatography,
129
gas chromatography,
130,131
and high-performance liquid chromatography.
132–134
In
order to improve the selectivity and/or the sensitivity of
the above-mentioned methods, several sample pretreat-
ment steps have also been proposed.
57,63,135,136
In partic-
ular, solid phase extraction
62,137
and other sample han-
dling strategies
31,32
were recently considered.
Capillary electrophoresis, microchips, and
electrochemical detection
Although a significant amount of information can be
obtained by standard chromatographic methodologies,
they are typically time consuming, need large sample vol-
umes, generate large amounts of waste, or require bulky
and expensive instrumentation. Capillary electrophoresis
is an alternative method for the separation of phenols. In
CE, the separation takes place inside of a small capillary
(<100 µm) filled with an electrolyte solution. When a
PHENOLIC COMPOUNDS continued
J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006 ###### J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006
FIGURE 1 Some of the most common applications of phenolic
compounds.
potential difference is applied across the capillary, bulk
flow of the solution is generated inside the capillary by a
process referred to as electroosmotic flow (EOF). The
analytes, which are introduced as a sample plug at one
end of the capillary, migrate toward the detector with a
velocity that is dependent on their charge/mass ratio, the
magnitude of the applied potential, and the solution con-
ditions. CE provides high-speed, high-throughput, low
waste generation, highly efficient, and reliable separa-
tions, and offers a simple way to handle very small sam-
ples (nL) without the use of pumps or valves. Another
advantage of CE is the possibility of using a wide range
of solution conditions to control the EOF and optimize
the separation of analytes.
138–142
Additionally, CE can be
miniaturized, while offering high performance, versatility,
reagent economy, speed, and automation capabilities.
143
Many different modes of detection can be coupled to
capillary electrophoresis systems.
106,107,144–151
Phenolic com-
pounds have been analyzed by capillary electrophoresis
with UV,
136,151
chemiluminescence,
138
MS,
152–154
inductively
coupled plasma-mass spectrometry (ICP-MS),
155
and elec-
trochemical
148,156,157
detection. CE can also be coupled to
flow injection analysis systems,
158
allowing on-line precon-
centration of phenols. Combined with electrochemical
detection (ECD), CE microchips can provide inherent minia-
turization, automation, and portability.
139
A review focused
on recent advances and the key strategies in microchip-CE
with electrochemical detection for separating and detecting
a variety of environmental pollutants was recently present-
ed by Chen et al.
159
Other publications dealing with differ-
ent aspects and applications of microchips for the analysis
of phenols have also been presented.
145,160–172
Amperometry is one of the most widely reported
ECD methods used in conjunction with CE microchips.
However, the possibility of fouling the working electrode
arises when using amperometry. Generally, this problem
can be avoided through a wide variety of strategies.
16,23,173
Among other approaches to improve the electrode life-
time, pulsed amperometric detection (PAD) was proven to
be effective for a large number of analytes.
174–176
PAD uti-
lizes a simple three-potential waveform in which the elec-
trode is first cleaned at a high positive potential, which
oxidizes the electrode; reactivated at a negative potential,
which dissolves the surface oxide; and then used to detect
the analyte at a moderate positive potential. Other advan-
tages of the use of PAD include a sensitivity comparable
(or better) to dc amperometry, speed, and the possibility
of performing direct detection of analytes that are nonelec-
trochemically active by other techniques.
175
Analysis of phenols with microchip-CE-PAD
The following sections will discuss the application
of poly(dimethylsiloxane) (PDMS) microchips coupled
to pulsed amperometric detection for the determination
of three groups of phenolic compounds. The first group
includes three U.S. EPA priority contaminants phenol,
pentachlorophenol, and 4,6-dinitro-o-cresol. The second
group includes four synthetic antioxidants: propyl gal-
late, octyl gallate, lauryl gallate, and nordihydroguaiaret-
ic acid. Finally, the third group includes four NSAIDs:
salicylic acid, acetaminophen, diflunisal, and diclofenac.
In all cases, the effect of different variables such as
composition of the background electrolyte, separation
potential, injection time, and detection waveform were
optimized considering the separation efficiency, signal
magnitude (peak current), and signal stability. In addi-
tion, different real samples were also analyzed in order
to demonstrate the potential applications of the system.
For the described experiments, a PDMS microchip
with a previously described design
177
was used (Figure
2). Briefly, a mold was fabricated using a silicon wafer
and SU-8 2035 negative photoresist (Microchem,
Newton, MA, U.S.A.). The height of the positive pattern
on the molding master, which represents the channel
depth created on the PDMS layer, was measured with a
profilometer. PDMS layers were fabricated by pouring a
degassed mixture of Sylgard 184 silicone elastomer and
curing agent (10:1) (Dow Corning, Midland, MI, U.S.A.)
onto either a molding master or a blank wafer, followed
by curing for at least 2 hr at 65 °C. The cured PDMS was
separated from the mold and reservoirs were made at
the end of each channel using a 6-mm circular punch.
A 25-µm gold wire was aligned at the end of the sepa-
ration channel in a perpendicular electrode channel to
serve as the working electrode. After that, the two
PDMS layers were placed in an air plasma cleaner, oxi-
dized for 20 sec, and immediately brought into confor-
mal contact to form an irreversible seal. Finally, the
extremities of the electrode channel were sealed with a
high-performance adhesive and the electrical connec-
tion to the working electrode was made using silver
paint and a copper wire.
PHENOLIC COMPOUNDS continued
J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006 ###### J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006
FIGURE 2 Schematic drawing of the microchip-CE with PAD.
Channel width: 50 µm, channel depth: 50 µm, double-T
arms: 4 mm long, double-T volume: 1.25 nL, separation
channel length: 70 mm, solution reservoirs: 6 mm diam,
detection electrode: 25 µm diam.
1. Pulsed amperometric detection. As stated above,
phenols can be electrochemically oxidized under a
wide range of conditions.
145,164,166,167,178,179
However, a
decrease in current is frequently observed if the elec-
trode is not protected or frequently polished.
16,18,23,180
PAD can minimize the electrode fouling and increase
the signal stability. In order to maximize the signal mag-
nitude of the different studied phenols, the potential
waveform must be optimized. Figure 3 shows the
hydrodynamic voltammograms corresponding to phe-
nol, propyl gallate, and acetaminophen. Although these
voltammograms were obtained under different condi-
tions, the general behavior does not change significant-
ly,
177,181,182
thus allowing the comparison of the three
data sets.
As can be observed in the three cases, the peak
current (Ip) increases as the detection potential increas-
es until a maximum is obtained. This maximum was
observed to be around +0.7 V for most of the studied
phenols except the antioxidants, for which the maxi-
mum current was obtained at +0.5 V. This finding is not
surprising because these compounds are designed to
protect goods from oxidation damage and therefore
must be easily oxidized. The current decrease observed
at higher potentials is the result of the formation of a
passivating oxide layer on the electrode surface.
182,183
The effect of other parameters, such as the cleaning
(oxidization) and reconstruction (reduction) potentials,
and the time length for each step must also be studied
considering the signal-to-noise ratio, signal stability, and
sampling frequency. It was observed that a +1.6-V/50-
msec oxidation step, followed by a –0.9-V/25-msec
reduction step effectively cleans the electrode, thus
increasing the signal stability and allowing a sampling
rate of 4.4 Hz (approximately 30 points/peak).
Pulsed electrochemical detection also requires
alkaline conditions in order to favor the formation of
gold (or platinum) oxide, which is fundamental for
cleaning the electrode.
183
Although phenols can be
oxidized at a wide range of pH values,
166,184,185
lower
limits of detection are typically obtained under alka-
line conditions.
18,23,173,180,181,186–188
If lower pH values
are required for the separation of a particular set of
phenols, the detection pH can be easily adjusted after
the separation.
181
Using microchip-CE-PAD, most of
the phenols can be detected with clear anodic peaks.
Moreover, no passivation problems were observed
when using the microchip-CE-PAD for a series of more
than 100 repetitive injections of a 90 µM phenol solu-
tion over 8 hr (Figure 4). The relative standard devia-
tions of migration time and electrochemical response
(Ip) were 1.6% and 6.1%, respectively. Such high sta-
bility is attributed to the successful use of PAD for
electrochemical cleaning of the working electrode.
Similar values were also obtained during the analysis
of antioxidants and NSAIDs. It was also observed that
if no preconcentration step is performed and sample
volumes in the nL range are used, limits of detection
in the low µM range can be obtained.
1–3
With only a
few exceptions,
189,190
these values are of the same
magnitude than previously reported for similar devices
and analytes.
22,118,145,162,169,191
PHENOLIC COMPOUNDS continued
J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006 ###### J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006
FIGURE 3 Hydrodynamic voltammograms corresponding to
phenol (–■–), propyl gallate (–●–), and acetaminophen
(–▲–). (Adapted from Refs. 1–3.)
FIGURE 4 Electrochemical response and migration time
obtained with repetitive injections of 90 µM phenol.
Conditions: 5 mM phosphate buffer pH = 12.4, injection
time: 10 sec, detection potential: +0.7 V, separation potential:
+1200 V. (Reproduced with permission from Ref. 1.)
2. Electrophoretic separation using microchips.
One of the most challenging aspects of microchip-CE is
to achieve the separation of analytes in a relatively short
channel. Simpler phenols (single substituted phenolic
ring) can be separated by CE using uncoated fused-sil-
ica capillaries.
158
Under alkaline conditions, the majori-
ty of the phenolic compounds become anions and
migrate according to their charge-to-mass ratio,
192
reflecting a clear dependence of electrophoretic mobil-
ity with respect to molecular weight. Using alkaline
conditions (5.0 mM phosphate buffer, pH 12.4), phenol,
4,6-dinitro-o-cresol, and pentachlorophenol were base-
line separated in less than 2 min using a microchip.
193
Salicylic acid, acetaminophen, diflunisal, and diclofenac
were also separated in less than 2 min using a 5 mM
borate buffer (pH 11.5) with no other additives.
3
Alkaline aqueous electrolytes are not suitable for
the separation of every phenolic compound due to
problems associated with solubility and stability.
16,18,23
In some of those cases, micellar electrokinetic chro-
matography (MEKC) has proven to be a very attractive
separation method.
191,194–196
MEKC is based on including
surfactants in the background electrolyte at concentra-
tions above the critical micelle concentration (CMC).
Under these conditions, a pseudostationary phase is
created, and micelles with a charged surface and a non-
polar core provide the means for the separation.
Generally, the partition coefficient of the analyte and
the micelle is the main factor determining selectivity.
More hydrophobic analytes have higher affinities for the
micelles and therefore are delayed with respect to the
migration time of more hydrophilic analytes. Sodium
dodecyl sulfate (SDS) was used for the separation of a
group of alkyl gallates and nordihydroguaiaretic acid.
2
In Figure 5, the dependence of the migration time of
these phenolic antioxidants as a function of SDS con-
centration is shown. As can be observed, a clear
decrease in the migration time (tM) was obtained for all
the selected compounds upon the first addition of SDS
(10 mM). This decrease in tM is the result of an increase
in electroosmotic flow produced by the adsorption of
SDS onto the PDMS surface.
142
As the SDS concentration
and the concentration of micelles was progressively
increased, the migration times of the antioxidants
increased while preserving the migration order. At 30
mM SDS, all of the peaks were baseline separated. It is
also worth mentioning that SDS not only improves the
separation, but also the electrochemical detection of
many compounds.
18,142,181,182,197,198
This is particularly
significant in the case of propyl gallate, for which the
peak current increased.
3. Effect of organic additives. The use of organic sol-
vents has been reported to improve separations by stan-
dard CE.
199
The resolution enhancement results from a
combination of a change in the viscosity of the electrolyte
and a change in the electroosmotic flow. However, most
of the organic solvents are either electrochemically active
under PAD or can adsorb to fresh electrode surfaces,
177
and decrease the signal-to-noise ratio. Although some
additives such as tetrahydrofuran (THF), alcohols, or ace-
tonitrile have improved the separations by CE,
200–203
their
use in combination with PAD is discouraged.
PHENOLIC COMPOUNDS continued
J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006 ###### J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006
a b
FIGURE 5 Effect of SDS concentration on the migration time (a) and peak current (b) for 28 µM propyl gallate (PG, –■–), 25 µM
octyl gallate (OG, –●–), 81 µM lauryl gallate (LG, –▲–), and 20 µM nordihydroguaiaretic acid (NDGA, –▼–). Other conditions:
10 mM borate (pH 9.6), separation potential: +1200 V (B–D), 5-sec injection, detection potential: +0.5 V. (Reproduced with per-
mission from Ref. 2.)
4. Effect of separation voltage. The separation
potential can be used to control EOF, resolution, and
the residence time of the analytes in the detection zone.
In order to evaluate the effect of separation potential, a
series of injections of standards were performed and the
migration times and signal magnitudes were evaluated.
As expected, when lower separation potentials were
applied, lower baseline noise and higher signal magni-
tudes were achieved, with a consequent increase in
analysis time. As a compromise between the analysis
time and the signal-to-noise ratio, +1200 V (171 V/cm)
was selected as the optimum separation voltage, at
which a baseline separation was typically achieved for
the selected analytes within 2 min.
5. Separation and real sample analysis. The suit-
ability of the CE microchip for separating low levels of
PHENOLIC COMPOUNDS continued
J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006 ###### J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006
a b
c
FIGURE 6 a) Separation and PAD of 67.7 µM phenol, 39.4 µM pentachlorophenol (PCP), and 25.0 µM 4,6-dinitro-o-cresol
(DNOC). Conditions: 5 mM phosphate buffer pH = 12.4, injection time: 10 sec, detection potential: +0.7 V, separation potential:
+1200 V. (Adapted from Ref. 1.) b) Electropherograms corresponding to a standard mixture (A), a food sample (B), and the food
sample spiked with propyl gallate (PG), nordihydroguaiaretic acid (NDGA), octyl gallate (OG), and lauryl gallate (LG) (C).
Conditions: 30 mM borate, 30 mm SDS pH = 9.6, detection potential: 0.5 V, 5-sec injection. (Reproduced with permission from
Ref. 2.) c) Electropherograms corresponding to a standard mixture and a bovine serum sample spiked with four NSAIDs.
Conditions: 5 mM borate (pH 11.5), separation potential: +1200 V (B–W), injection time: 5 sec, oxidation potential: 1.6 V,
reduction potential: –0.9 V, detection potential: + 0.7 V. (Adapted from Ref. 3.)
phenolic compounds was demonstrated. Figure 6a
shows an electropherogram obtained with a standard
mixture of phenols (pentachlorophenol, 4,6-dinitro-o-
cresol, and phenol). Clear peaks were also observed for
all of the studied compounds, showing recovery assays
of about 95% when spiked city water or sore throat
medicine samples were analyzed.
193
Figure 6b shows
the electropherograms corresponding to a standard
mixture of antioxidants and the analysis of a commer-
cial food sample containing propyl gallate.
2
As can be
observed, the baseline separation of the four selected
antioxidants was achieved in less than 2 min. Using the
optimized conditions, a gravy mix sample was also ana-
lyzed (b), and the corresponding amount of propyl gal-
late was calculated to be 45 mg of PG/kg of sample.
Figure 6c shows the electropherograms corresponding
to four NSAIDs and a bovine serum sample spiked with
the selected compounds. Although lower yields were
obtained for salicylic acid (72 ± 5%), good recoveries
were obtained for the case of acetaminophen (90 ± 5%),
diclofenac (99 ± 6%), and diflunisal (81 ± 6%).
3
Conclusion
This minireview describes recent applications of
microchip-CE with pulsed amperometric detection for
the analysis of different phenolic compounds.
Specifically, the discussed methodologies illustrate prac-
tical, simple, rapid, and inexpensive methods for the
simultaneous analysis of contaminants, antioxidants, and
pharmaceutical compounds. Under the optimum condi-
tions, the selected compounds were baseline separated
within 2 min and detected above the low-µM range.
Although the presented system offers a low-cost,
portable, and custom-made device for the analysis of
very small (nL) samples, the detection limits must be
improved in order to allow effective applicability to real-
world problems. Without a doubt, microchip-CE-PAD has
the potential to become a well-established methodology
for the analysis of phenolics in a wide variety of samples.
Acknowledgment
We thank The University of Texas at San Antonio
and the San Antonio Area Foundation for financial sup-
port. E. Mejia also thanks the MBRS-RISE program for the
research fellowship (NIH/NIGMS MBRS-RISE GM60655).
©Copyright 2006. ISC Technical Publications, Inc.
Manuscript received ???.
References
1. Ding, Y.; García, C.D. Pulsed amperometric detection with
poly(dimethylsiloxane)-fabricated capillary electrophoresis
microchips for the determination of EPA priority pollutants.
Analyst 2006, 131, 208–14.
2. Ding, Y.; Mora, M.F.; García, C.D. Analysis of alkyl gallates and
nordihydroguaiaretic acid using plastic capillary electrophore-
sis–microchips. Anal. Chim. Acta 2006, 561, 126–32.
3. Ding, Y.; García, C.D. Determination of non-steroidal anti-
inflammatory drugs in serum by capillary electrophoresis
microchip and electrochemical detection. J. Chromatogr. B, sub-
mitted 2006.
4. Nistor, C.; Rose, A.; Farré, M.; Stoica, L.; Wollenberger, U.;
Ruzgas, T.; Pfeiffer, D.; Barceló, D.; Gorton, L.; Emnéus, J. In-
field monitoring of cleaning efficiency in waste water treatment
plants using two phenol-sensitive biosensors. Anal. Chim. Acta
2002, 456, 3–17.
5. Veeresh, G.S.; Kumar, P.; Mehrotra, I. Treatment of phenol and
cresols in upflow anaerobic sludge blanket (UASB) process: a
review. Water Res. 2005, 39, 154–70.
6. Amen-Chen, C.; Pakdel, H.; Roy, C. Production of monomeric
phenols by thermochemical conversion of biomass: a review.
Bioresource Technol. 2001, 79, 277–99.
7. Takeda, S.; Tanaka, Y.; Yamane, M.; Siroma, Z.; Wakida, S.;
Otsuka, K.; Terabe, S. Ionization of dichlorophenols for their
analysis by capillary electrophoresis-mass spectrometry. J.
Chromatogr. A 2001, 924, 415–20.
8. Tsukagoshi, K.; Kameda, T.; Yamamoto, M.; Nakajima, R.
Separation and determination of phenolic compounds by capil-
lary electrophoresis with chemiluminescence detection. J.
Chromatogr. A 2002, 978, 213–20.
9. Harrison, M.A.J.; Barra, S.; Borghesi, D.; Vione, D.; Arsene, C.;
Iulian Olariu, R. Nitrated phenols in the atmosphere: a review.
Atmos. Environ. 2005, 39, 231–48.
10. Pokhrel, D.; Viraraghavan, T. Treatment of pulp and paper mill
wastewater—a review. Sci. Total Environ. 2004, 333, 37–58.
11. Babich, H.; Davis, D.L. Phenol: a review of environmental and
health risks. Regul. Toxicol. Pharmacol. 1981, 1, 90–109.
12. Bruce, R.M.; Santodonato, J.; Neal, M.W. Summary review of the
health effects associated with phenol. Toxicol. Ind. Health 1987,
3, 535–68.
13. Samanta, S.K.; Singh, O.V.; Jain, R.K. Polycyclic aromatic hydro-
carbons: environmental pollution and bioremediation. Trends
Biotechnol. 2002, 20, 243–8.
14. Barr, D.B.; Turner, W.E.; DiPietro, E.; McClure, P.C.; Baker, S.E.;
Barr, J.R.; Gehle, K.; Grissom, Jr., R.E.; Bravo, R.; Driskell, W.J.;
Patterson, Jr., D.G.; Hill, Jr., R.H.; Needham, L.L.; Pirkle, J.L.;
Sampson, E.J. Measurement of p-nitrophenol in the urine of res-
idents whose homes were contaminated with methyl parathion.
Environ. Health Perspect. 2002, 110, 1085–91.
15. Noguchi, N.; Niki, E. Phenolic antioxidants: a rationale for
design and evaluation of novel antioxidant drug for atheroscle-
rosis. Free Radical Biol. Med. 2000, 28
, 1538–46.
16. García, C.D.; Ortiz, P.I. BHA and TBHQ quantification in cosmet-
ic samples. Electroanalysis 2000, 12, 1074–6.
17. Thorsen, M.A.; Hildebrandt, K.S. Quantitative determination of
phenolic diterpenes in rosemary extracts. Aspects of accurate
quantification. J. Chromatogr. A 2003, 995, 119–25.
18. Hompesch, R.W.; García, C.D.; Weiss, D.J.; Vivanco, J.M.; Henry,
C.S. Analysis of natural flavonoids by microchip-micellar electro-
kinetic chromatography with pulsed amperometric detection.
Analyst 2005, 130, 694–700.
19. Bernabei, M.; Bocchinfuso, G.; Carrozzo, P.; De Angelis, C.
Determination of phenolic antioxidants in aviation jet fuel. J.
Chromatogr. A 2000, 871, 235–41.
20. Blanco, M.; Coello, J.; Iturriaga, H.; Maspoch, S.; Bertran, E.
Determination of accelerators and antioxidants in vulcanized
rubber by Fourier transform infrared spectrophotometry. Anal.
Chim. Acta 1997, 353, 351–8.
21. Fries, E.; Puttmann, W. Analysis of the antioxidant butylated
hydroxytoluene (BHT) in water by means of solid phase extrac-
tion combined with GC/MS. Water Res. 2002, 36, 2319–27.
PHENOLIC COMPOUNDS continued
J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006 ###### J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006
22. Ceballos, C.; Fernandez, H. Synthetic antioxidants determination
in lard and vegetable oils by the use of voltammetric methods
on disk ultramicroelectrodes. Food Res. Int. 2000, 33, 357–65.
23. García, C.D.; Ortiz, P.I. Determination of tert-butylhydroxy-
toluene by flow injection analysis at polymer modified glassy
carbon electrodes. Electroanalysis 1998, 10, 832–5.
24. Vulic, I.; Vitarelli, G.; Zenner, J.M. Structure-property relation-
ships: phenolic antioxidants with high efficiency and low colour
contribution. Polym. Degrad. Stab. 2002, 78, 27–34.
25. Manzocco, L.; Calligaris, S.; Mastrocola, D.; Nicoli, M.C.; Lerici,
C.R. Review of non-enzymatic browning and antioxidant capac-
ity in processed foods. Trends Food Sci. Technol. 2000, 11,
340–6.
26. Lupo, M.P. Antioxidants and vitamins in cosmetics. Clin.
Dermatol. 2001, 19, 467–73.
27. Botterweck, A.A.M.; Verhagen, H.; Goldbohm, R.A.; Kleinjans, J.;
van den Brandt, P.A. Intake of butylated hydroxyanisole and
butylated hydroxytoluene and stomach cancer risk: results from
analyses in the Netherlands Cohort Study. Food Chem. Toxicol.
2000, 38, 599–605.
28. Iverson, F. Phenolic antioxidants: Health Protection Branch stud-
ies on butylated hydroxyanisole. Cancer Lett. 1995, 93, 49–54.
29. Schuberta, S.Y.; Lanskyb, E.P.; Neeman, I. Antioxidant and
eicosanoid enzyme inhibition properties of pomegranate seed
oil and fermented juice flavonoids. J. Ethnopharmacol. 1999,
66, 11–17.
30. Williams, G.M.; Iatropoulos, M.J.; Whysner, J. Safety assessment
of butylated hydroxyanisole and butylated hydroxytoluene as
antioxidant food additives. Food Chem. Toxicol. 1999, 37,
1027–38.
31. Robards, K. Strategies for the determination of bioactive phenols
in plants, fruit and vegetables. J. Chromatogr. A 2003, 1000,
657–91.
32. Tura, D.; Robards, K. Sample handling strategies for the determi-
nation of biophenols in food and plants. J. Chromatogr. A 2002,
975, 71–93.
33. Servili, M.; Selvaggini, R.; Esposto, S.; Taticchi, A.; Montedoro,
G.; Morozzi, G. Health and sensory properties of virgin olive oil
hydrophilic phenols: agronomic and technological aspects of
production that affect their occurrence in the oil. J. Chromatogr.
A 2004, 1054, 113–27.
34. Wang, K.-J.; Zhang, Y.-J.; Yang, C.-R. Antioxidant phenolic com-
pounds from rhizomes of Polygonum paleaceum. J.
Ethnopharmacol. 2005, 96, 483–7.
35. Tuck, K.L.; Hayball, P.J. Major phenolic compounds in olive oil:
metabolism and health effects.
J. Nutr. Biochem. 2002, 13, 636–44.
36. Weiss, D.J.; Anderton, C.R. Determination of catechins in matcha
green tea by micellar electrokinetic chromatography. J.
Chromatogr. A 2003, 1011, 173–80.
37. Tsao, R.; Deng, Z. Separation procedures for naturally occurring
antioxidant phytochemicals. J. Chromatogr. B 2004, 812, 85–99.
38. Vanderhaegen, B.; Neven, H.; Verachtert, H.; Derdelinckx, G.
The chemistry of beer aging—a critical review. Food Chem.
2006, 95, 357–81.
39. Lee, K.Y.; Weintraub, S.T.; Yu, B.P. Isolation and identification of
a phenolic antioxidant from Aloe barbadensis. Free Radical
Biology and Medicine 2000, 28, 261–5.
40. Wang, M.; Simon, J.E.; Aviles, I.F.; He, K.; Zheng, Q.Y.; Tadmor,
Y. Analysis of antioxidative phenolic compounds in artichoke
(Cynara scolymus L.). J. Agric. Food Chem. 2003, 51, 601–8.
41. Slater, S.J.; Seiz, J.L.; Cook, A.C.; Stagliano, B.A.; Buzas, C.J.
Inhibition of protein kinase C by resveratrol. Biochim. Biophys.
Acta 2003, 1637, 59–69.
42. Savouret, J.F.; Quesne, M. Resveratrol and cancer: a review.
Biomed. Pharmacother. 2002, 56, 84–7.
43. Schmitt, E.; Lehmann, L.; Metzler, M.; Stopper, H. Hormonal and
genotoxic activity of resveratrol. Toxicol. Lett. 2002, 136, 133–42.
44. Vitrac, X.; Monti, J.-P.; Vercauteren, J.; Deffieux, G.; Merillon, J.-
M. Direct liquid chromatographic analysis of resveratrol deriva-
tives and flavanonols in wines with absorbance and fluorescence
detection. Anal. Chim. Acta 2002, 458, 103–10.
45. Gu, X.; Chu, Q.; O’Dwyer, M.; Zeece, M. Analysis of resveratrol
in wine by capillary electrophoresis. J. Chromatogr. A 2000, 881,
471–81.
46. Prior, R.L.; Wu, X.; Schaich, K. Standardized methods for the
determination of antioxidant capacity and phenolics in foods
and dietary supplements. J. Agric. Food Chem. 2005, 53,
4290–4302.
47. Gonzalez-Paramas, A.M.; Lopes da Silva, F.; Martin-Lopez, P.;
Macz-Pop, G.; Gonzalez-Manzano, S.; Alcalde-Eon, C.; Perez-
Alonso, J.J.; Escribano-Bailon, M.T.; Rivas-Gonzalo, J.C.; Santos-
Buelga, C. Flavanol-anthocyanin condensed pigments in plant
extracts. Food Chem. 2006, 94, 428–36.
48. Fernandez, P.L.; Pablos, F.; Martin, M.J.; Gonzalez, A.G. Study of
catechin and xanthine tea profiles as geographical tracers. J.
Agric. Food Chem.
2002, 50, 1833–9.
49. Weir, T.L.; Park, S.-W.; Vivanco, J.M. Biochemical and physiolog-
ical mechanisms mediated by allelochemicals. Curr. Opinion
Plant Biol. 2004, 7, 472–9.
50. Wang, H.; Provan, G.J.; Helliwell, K. HPLC determination of cat-
echins in tea leaves and tea extracts using relative response fac-
tors. Food Chem. 2003, 81, 307–12.
51. Toyo’oka, T.; Kashiwazaki, T.; Kato, M. On-line screening meth-
ods for antioxidants scavenging superoxide anion radical and
hydrogen peroxide by liquid chromatography with indirect
chemiluminescence detection. Talanta 2003, 60, 467–75.
52. Suntornsuk, L.; Kasemsook, S.; Wongyai, S. Quantitative analysis
of aglycone quercetin in mulberry leaves (Morus alba L.) by cap-
illary zone electrophoresis. Electrophoresis 2003, 24, 1236–41.
53. Lampart-Szczapa, E.; Korczak, J.; Nogala-Kalucka, M.; Zawirska-
Wojtasiak, R. Antioxidant properties of lupin seed products.
Food Chem. 2003, 83, 279–85.
54. Gosslau, A.; Chen, K.Y. Nutraceuticals, apoptosis, and disease
prevention. Nutrition 2004, 20, 95–102.
55. Dargan, P.I.; Wallace, C.I.; Jones, A.L. An evidence based flow-
chart to guide the management of acute salicylate (aspirin) over-
dose. Emerg. Med. J. 2002, 19, 206–9.
56. Oaks, J.L.; Gilbert, M.; Virani, M.Z.; Watson, R.T.; Meteyer, C.U.;
Rideout, B.A.; Shivaprasad, H.L.; Ahmed, S.; Chaudhry, M.J.;
Arshad, M.; Mahmood, S.; Ali, A.; Khan, A.A. Diclofenac residues
as the cause of vulture population decline in Pakistan. Nature
2004, 427, 630–3.
57. Carabias-Martinez, R.; García-Hermida, C.; Rodriguez-Gonzalo,
F.E.; Soriano-Bravo, E.; Hernandez-Mendez, J. Determination of
herbicides, including thermally labile phenylureas, by solid-
phase microextraction and gas chromatography-mass spectrom-
etry. J. Chromatogr. A 2003, 1002, 1–12.
58. Sanchez-Rabaneda, F.; Jauregui, O.; Lamuela-Raventos, R.M.;
Bastida, J.; Viladomat, F.; Codina, C. Identification of phenolic
compounds in artichoke waste by high-performance liquid chro-
matography-tandem mass spectrometry. J. Chromatogr. A 2003,
1008, 57–72.
59. Suliman, F.E.; Al-Kindi, S.S.; Al-Kindy, S.M.; Al-Lawati, H.A.
Analysis of phenols in water by high-performance liquid chro-
matography using coumarin-6-sulfonyl chloride as a fluorogenic
precolumn label. J. Chromatogr. A 2006, 1101, 179–84.
60. Yarita, T.; Nakajima, R.; Shibukawa, M. Superheated water chro-
matography of phenols using poly(styrene-divinylbenzene)
packings as a stationary phase. Anal. Sci. 2003, 19, 269–72.
61. Zhao, L.; Lee, H.K. Determination of phenols in water using liq-
uid phase microextraction with back extraction combined with
high-performance liquid chromatography. J. Chromatogr. A
2001, 931, 95–105.
62. Wissiack, R.; Rosenberg, E.; Grasserbauer, M. Comparison of differ-
ent sorbent materials for on-line solid-phase extraction with liquid
PHENOLIC COMPOUNDS continued
J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006 ###### J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006
chromatography-atmospheric pressure chemical ionization mass
spectrometry of phenols. J. Chromatogr. A 2000, 896, 159–70.
63. Penalver, A.; Pocurull, E.; Borrull, F.; Marce, R.M. Solid-phase
microextraction coupled to high-performance liquid chromatog-
raphy to determine phenolic compounds in water samples. J.
Chromatogr. A 2002, 953, 79–87.
64. Saraji, M.; Bakhshi, M. Determination of phenols in water sam-
ples by single-drop microextraction followed by in-syringe
derivatization and gas chromatography-mass spectrometric
detection. J. Chromatogr. A 2005, 1098, 30–6.
65. Hanada, Y.; Imaizumi, I.; Kido, K.; Tanizaki, T.; Koga, M.;
Shiraishi, H.; Soma, M. Application of a pentafluorobenzyl bro-
mide derivatization method in gas chromatography/mass spec-
trometry of trace levels of halogenated phenols in air, water and
sediment samples. Anal. Sci. 2002, 18, 655–9.
66. Llompart, M.; Lourido, M.; Landin, P.; García-Jares, C.; Cela, R.
Optimization of a derivatization-solid-phase microextraction
method for the analysis of thirty phenolic pollutants in water
samples. J. Chromatogr. A 2002, 963, 137–48.
67. Montero, L.; Conradi, S.; Weiss, H.; Popp, P. Determination of
phenols in lake and ground water samples by stir bar sorptive
extraction-thermal desorption-gas chromatography-mass spec-
trometry. J. Chromatogr. A 2005, 1071, 163–9.
68. Blythe, J.W.; Heitz, A.; Joll, C.A.; Kagi, R.I. Determination of trace
concentrations of bromophenols in water using purge-and-trap
after in situ acetylation. J. Chromatogr. A 2006, 1102, 73–83.
69. Basheer, C.; Parthiban, A.; Jayaraman, A.; Lee, H.K.; Valiyaveettil,
S. Determination of alkylphenols and bisphenol-A. A compara-
tive investigation of functional polymer-coated membrane
microextraction and solid-phase microextraction techniques. J.
Chromatogr. A 2005, 1087, 274–82.
70. Faraji, H. Beta-cyclodextrin-bonded silica particles as the solid-
phase extraction medium for the determination of phenol com-
pounds in water samples followed by gas chromatography with
flame ionization and mass spectrometry detection. J.
Chromatogr. A 2005, 1087, 283–8.
71. Ieda, T.; Horii, Y.; Petrick, G.; Yamashita, N.; Ochiai, N.; Kannan,
K. Analysis of nonylphenol isomers in a technical mixture and in
water by comprehensive two-dimensional gas chromatography-
mass spectrometry. Environ. Sci. Technol. 2005, 39, 7202–7.
72. Ikarashi, Y.; Kaniwa, M.A.; Tsuchiya, T. Monitoring of polycyclic
aromatic hydrocarbons and water-extractable phenols in cre-
osotes and creosote-treated woods made and procurable in
Japan. Chemosphere 2005, 60, 1279–87.
73. Kojima, M.; Matsui, N.; Tsunoi, S.; Tanaka, M. Ion-pair solid-
phase extractive derivatization of 4-alkylphenols with pentafluo-
ropyridine for gas chromatography-mass spectrometry. J.
Chromatogr. A 2005, 1078, 1–6.
74. Lee, H.B.; Peart, T.E.; Svoboda, M.L. Determination of endocrine-
disrupting phenols, acidic pharmaceuticals, and personal-care
products in sewage by solid-phase extraction and gas chro-
matography-mass spectrometry. J. Chromatogr. A 2005, 1094,
122–9.
75. Vermeulen, A.; Welvaert, K.; Vercammen, J. Evaluation of a ded-
icated gas chromatography-mass spectrometry method for the
analysis of phenols in water. J. Chromatogr. A 2005,
1071, 41–6.
76. Fiamegos, Y.C.; Nanos, C.G.; Pilidis, G.A.; Stalikas, C.D. Phase-
transfer catalytic determination of phenols as methylated deriva-
tives by gas chromatography with flame ionization and mass-
selective detection. J. Chromatogr. A 2003, 983, 215–23.
77. Zhou, F.; Li, X.; Zeng, Z. Determination of phenolic compounds
in wastewater samples using a novel fiber by solid-phase
microextraction coupled to gas chromatography. Anal. Chim.
Acta 2005, 538, 63–??.
78. Boitsov, S.; Meier, S.; Klungsoyr, J.; Svardal, A. Gas chromatog-
raphy-mass spectrometry analysis of alkylphenols in produced
water from offshore oil installations as pentafluorobenzoate
derivatives. J. Chromatogr. A 2004, 1059, 131–41.
79. Bagheri, H.; Saber, A.; Mousavi, S.R. Immersed solvent microex-
traction of phenol and chlorophenols from water samples fol-
lowed by gas chromatography-mass spectrometry. J. Chromatogr.
A 2004, 1046, 27–33.
80. Nakamura, S.; Daishima, S. Simultaneous determination of alkylphe-
nols and bisphenol A in river water by stir bar sorptive extraction
with in situ acetylation and thermal desorption-gas chromatography-
mass spectrometry. J. Chromatogr. A 2004, 1038, 291–4.
81. Stolyhwo, A.; Sikorski, Z.E. Polycyclic aromatic hydrocarbons in
smoked fish—a critical review. Food Chem. 2005, 91, 303–11.
82. Wissiack, R.; Rosenberg, E. Universal screening method for the
determination of U.S. Environmental Protection Agency phenols
at the lower ng l(–1) level in water samples by on-line solid-
phase extraction-high-performance liquid chromatography-
atmospheric pressure chemical ionization mass spectrometry
within a single run. J. Chromatogr. A 2002, 963, 149–57.
83. Karovicova, J.; Simko, P. Determination of synthetic phenolic
antioxidants in food by high-performance liquid chromatogra-
phy. J. Chromatogr. A 2000, 882, 271–81.
84. Insa, S.; Antico, E.; Ferreira, V. Highly selective solid-phase
extraction and large volume injection for the robust gas chro-
matography-mass spectrometric analysis of TCA and TBA in
wines. J. Chromatogr. A 2005, 1089, 235–42.
85. Diez, J.; Dominguez, C.; Guillen, D.A.; Veas, R.; Barroso, C.G.
Optimisation of stir bar sorptive extraction for the analysis of
volatile phenols in wines. J. Chromatogr. A 2004, 1025, 263–7.
86. Castro Mejias, R.; Natera Marin, R.; García Moreno Mde, V.;
García Barroso, C. Optimisation of headspace solid-phase
microextraction for the analysis of volatile phenols in wine. J.
Chromatogr. A 2003, 995, 11–20.
87. Watson, D.G.; Atsriku, C.; Oliveira, E.J. Review role of liquid
chromatography-mass spectrometry in the analysis of oxidation
products and antioxidants in biological systems. Anal. Chim.
Acta 2003, 492, 17–47.
88. Kubo, I.; Fujita, K.; Nihei, K.; Nihei, A. Antibacterial activity of
akyl gallates against Bacillus subtilis. J. Agric. Food Chem. 2004,
52, 1072–6.
89. Pellati, F.; Benvenuti, S.; Melegari, M.; Lasseigne, T. Variability in
the composition of anti-oxidant compounds in
Echinacea
species by HPLC. Phytochem. Anal. 2005, 16, 77–85.
90. Rehova, L.; Skerikova, V.; Jandera, P. Optimisation of gradient
HPLC analysis of phenolic compounds and flavonoids in beer
using a coularray detector. J. Sep. Sci. 2004, 27, 1345–59.
91. Bedgood, Jr., D.R.; Bishop, A.G.; Prenzler, P.D.; Robards, K.
Analytical approaches to the determination of simple biophenols
in forest trees such as Acer (maple), Betula (birch), Coniferus,
Eucalyptus, Juniperus (cedar), Picea (spruce) and Quercus
(oak). Analyst 2005, 130, 809–23.
92. Ryan, D.; Prenzler, P.D.; Lavee, S.; Antolovich, M.; Robards, K.
Quantitative changes in phenolic content during physiological
development of the olive (Olea europaea) cultivar Hardy's
Mammoth. J. Agric. Food Chem. 2003, 51, 2532–8.
93. Ryan, D.; Antolovich, M.; Herlt, T.; Prenzler, P.D.; Lavee, S.;
Robards, K. Identification of phenolic compounds in tissues of
the novel olive cultivar hardy's mammoth. J. Agric. Food Chem.
2002, 50, 6716–24.
94. Dokhani, S.; Cottrell, T.; Khajeddin, J.; Mazza, G. Analysis of
aroma and phenolic components of selected Achillea species.
Plant Foods Hum. Nutr. 2005, 60, 55–62.
95. Sudjaroen, Y.; Haubner, R.; Wurtele, G.; Hull, W.E.; Erben, G.;
Spiegelhalder, B.; Changbumrung, S.; Bartsch, H.; Owen, R.W.
Isolation and structure elucidation of phenolic antioxidants from
Tamarind (Tamarindus indica L.) seeds and pericarp. Food
Chem. Toxicol. 2005, 43, 1673–82.
96. Yang, L.; Wang, Z.; Xu, L. Simultaneous determination of phe-
nols (bibenzyl, phenanthrene, and fluorenone) in Dendrobium
species by high-performance liquid chromatography with diode
array detection. J. Chromatogr. A 2005, 1104, 230–7.
PHENOLIC COMPOUNDS continued
J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006 ###### J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006
97. Bravo, R.; Caltabiano, L.M.; Fernandez, C.; Smith, K.D.; Gallegos,
M.; Whitehead, Jr., R.D.; Weerasekera, G.; Restrepo, P.; Bishop,
A.M.; Perez, J.J.; Needham, L.L.; Barr, D.B. Quantification of phe-
nolic metabolites of environmental chemicals in human urine
using gas chromatography-tandem mass spectrometry and iso-
tope dilution quantification. J. Chromatogr. B 2005, 820, 229–36.
98. Kawaguchi, M.; Sakui, N.; Okanouchi, N.; Ito, R.; Saito, K.;
Izumi, S.; Makino, T.; Nakazawa, H. Stir bar sorptive extraction
with in situ derivatization and thermal desorption-gas chro-
matography-mass spectrometry for measurement of phenolic
xenoestrogens in human urine samples. J. Chromatogr. B 2005,
820, 49–57.
99. Orejuela, E.; Silva, M. Sensitive determination of low molecular
mass phenols by liquid chromatography with chemilumines-
cence detection for the determination of phenol and 4-
methylphenol in urine. Analyst 2002, 127, 1433–9.
100. Cruces-Blanco, C.; Segura Carretero, A.; Merino Boyle, E.;
Fernandez Gutierrez, A. The use of dansyl chloride in the spec-
trofluorimetric determination of the synthetic antioxidant buty-
lated hydroxyanisole in foodstuffs. Talanta 1999, 50,
1099–1108.
101. Capitan-Vallvey, L.F.; Valencia, M.C.; Arana Nicolas, E. Solid-
phase ultraviolet absorbance spectrophotometric multisensor for
the simultaneous determination of butylated hydroxytoluene
and co-existing antioxidants. Anal. Chim. Acta 2004, 503,
179–86.
102. de la Fuente, C.; Acuna, J.A.; Vazquez, M.D.; Tascon, M.L.;
Sanchez Batanero, P. Voltammetric determination of the pheno-
lic antioxidants 3-tert-butyl-4-hydroxyanisole and tert-butylhy-
droquinone at a polypyrrole electrode modified with a nickel
phthalocyanine complex. Talanta 1999, 49, 441–52.
103. Luque, M.; Rios, A.; Valcarcel, M. A poly(vinyl chloride) graphite
composite electrode for flow-injection amperometric determina-
tion of antioxidants. Anal. Chim. Acta 1999, 395, 217–23.
104. Capitan-Vallvey, L.F.; Valencia, M.C.; Nicolas, E.A.
Monoparameter sensors for the determination of the antioxi-
dants butylated hydroxyanisole and n-propyl gallate in foods
and cosmetics by flow injection spectrophotometry. Analyst
2001, 126, 897–902.
105. Bonoli, M.; Montanucci, M.; Gallina Toschi, T.; Lercker, G. Fast
separation and determination of tyrosol, hydroxytyrosol and
other phenolic compounds in extra-virgin olive oil by capillary
zone electrophoresis with ultraviolet-diode array detection. J.
Chromatogr. A 2003, 1011, 163–72.
106. Hernandez-Borges, J.; Gonzalez-Hernandez, G.; Borges-Miquel,
T.; Rodriguez-Delgado, M.A. Determination of antioxidants in
edible grain derivatives from the Canary Islands by capillary
electrophoresis. Food Chem. 2005, 91, 105–11.
107. Jac, P.; Polasek, M.; Pospisilova, M. Recent trends in the deter-
mination of polyphenols by electromigration methods. J. Pharm.
Biomed. Anal. 2006, 40, 805–14.
108. Li, Y.-F.; Liu, Z.-M.; Liu, Y.-L.; Yang, Y.-H.; Shen, G.-L.; Yu,
R.-Q. A mediator-free phenol biosensor based on immobiliz-
ing tyrosinase to ZnO nanoparticles. Anal. Biochem. 2006,
349, 33–40.
109. Roy, J.J.; Abraham, T.E.; Abhijith, K.S.; Kumar, P.V.; Thakur, M.S.
Biosensor for the determination of phenols based on cross-
linked enzyme crystals (CLEC) of laccase. Biosens. Bioelectron.
2005, 21, 206–11.
110. Liu, Z.; Liu, Y.; Yang, H.; Yang, Y.; Shen, G.; Yu, R. A phenol
biosensor based on immobilizing tyrosinase to modified core-
shell magnetic nanoparticles supported at a carbon paste elec-
trode. Anal. Chim. Acta 2005, 533, 3–9.
111. Craig, J.D.; O’Neill, R.D. Electrosynthesis and permselective
characterisation of phenol-based polymers for biosensor appli-
cations. Anal. Chim. Acta 2003, 495, 33–43.
112. Freire, R.S.; Ferreira, M.M.C.; Duran, N.; Kubota, L.T. Dual
amperometric biosensor device for analysis of binary mixtures of
phenols by multivariate calibration using partial least squares.
Anal. Chim. Acta 2003, 485, 263–9.
113. Kim, M.A.; Lee, W.-Y. Amperometric phenol biosensor based on
sol-gel silicate/Nafion composite film. Anal. Chim. Acta 2003,
479, 143–50.
114. Liu, S.; Yu, J.; Ju, H. Renewable phenol biosensor based on a
tyrosinase-colloidal gold modified carbon paste electrode. J.
Electroanal. Chem. 2003, 540, 61–7.
115. Rosatto, S.S.; Sotomayor, P.T.; Kubota, L.T.; Gushikem, Y.
SiO
2
/Nb
2
O
5
sol-gel as a support for HRP immobilization in
biosensor preparation for phenol detection. Electrochim. Acta
2002, 47, 4451–8.
116. Mailley, P.; Cummings, E.A.; Mailley, S.; Cosnier, S.; Eggins, B.R.;
McAdams, E. Amperometric detection of phenolic compounds
by polypyrrole-based composite carbon paste electrodes.
Bioelectrochem. 2004, 63, 291–6.
117. Mailley, P.; Cummings, E.A.; Mailley, S.C.; Eggins, B.R.;
McAdams, E.; Cosnier, S. Composite carbon paste biosensor for
phenolic derivatives based on in situ electrogenerated polypyr-
role binder. Anal. Chem. 2003, 75, 5422–8.
118. Morales, M.D.; Gonzalez, M.C.; Reviejo, A.J.; Pingarron, J.M. A
composite amperometric tyrosinase biosensor for the determina-
tion of the additive propyl gallate in foodstuffs. Microchem. J.
2005, 80, 71–8.
119. Mu, S. Catechol sensor using poly(aniline-co-o-aminophenol) as
an electron transfer mediator. Biosens. Bioelectron. 2006, 21,
1237–43.
120. Tingry, S.; Innocent, C.; Touil, S.; Deratani, A.; Seta, P. Carbon
paste biosensor for phenol detection of impregnated tissue:
modification of selectivity by using [beta]-cyclodextrin-contain-
ing PVA membrane. Mater. Sci. Eng. C 2006, 26, 222–6.
121. Vianello, F.; Ragusa, S.; Cambria, M.T.; Rigo, A. A high sensitivi-
ty amperometric biosensor using laccase as biorecognition ele-
ment. Biosens. Bioelectron, in press (2006).
122. Serra, B.; Morales, M.D.; Reviejo, A.J.; Hall, E.H.; Pingarron, J.M.
Rapid and highly sensitive electrochemical determination of
alkaline phosphatase using a composite tyrosinase biosensor.
Anal. Biochem. 2005, 336, 289–94.
123. Carralero Sanz, V.; Mena, M.L.; Gonzalez-Cortes, A.; Yanez-
Sedeno, P.; Pingarron, J.M. Development of a tyrosinase biosen-
sor based on gold nanoparticles-modified glassy carbon elec-
trodes: application to the measurement of a bioelectrochemical
polyphenols index in wines. Anal. Chim. Acta 2005, 528, 1–8.
124. Duran, N.; Rosa, M.A.; rsquo, Annibale, A.; Gianfreda, L.
Applications of laccases and tyrosinases (phenoloxidases) immo-
bilized on different supports: a review. Enzyme Microb. Technol.
2002, 31, 907–31.
125. Song, W.; Dou, C. One-step immunoassay for acetaminophen
and salicylate in serum, plasma, and whole blood. J. Anal.
Toxicol. 2003, 27, 366–71.
126. Papatheodoridis, G.V.; Papadelli, D.; Cholongitas, E.;
Vassilopoulos, D.; Mentis, A.; Hadziyannis, S.J. Effect of heli-
cobacter pylori infection on the risk of upper gastrointestinal
bleeding in users of nonsteroidal anti-inflammatory drugs. Am.
J. Med. 2004, 116, 601–5.
127. Ferreira, H.; Lucio, M.; de Castro, B.; Gameiro, P.; Lima, J.L.; Reis,
S. Partition and location of nimesulide in EPC liposomes: a spec-
trophotometric and fluorescence study. Anal. Bioanal. Chem.
2003, 377, 293–8.
128. Erk, N. Application of derivative-differential UV spectrophotom-
etry and ratio derivative spectrophotometric determination of
mephenoxalone and acetaminophen in combined tablet prepa-
ration. J. Pharm. Biomed. Anal. 1999, 21, 429–37.
129. Maurer, H.H. Systematic toxicological analysis procedures for
acidic drugs and/or metabolites relevant to clinical and forensic
toxicology and/or doping control. J. Chromatogr. B 1999, 733,
3–25.
PHENOLIC COMPOUNDS continued
J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006 ###### J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006
130. Maurer, H.H.; Tauvel, F.X.; Kraemer, T. Screening procedure for
detection of non-steroidal anti-inflammatory drugs and their
metabolites in urine as part of a systematic toxicological analy-
sis procedure for acidic drugs and poisons by gas chromatogra-
phy-mass spectrometry after extractive methylation. J. Anal.
Toxicol. 2001, 25, 237–44.
131. Kim, K.R.; Yoon, H.R. Rapid screening for acidic non-steroidal
anti-inflammatory drugs in urine by gas chromatography-mass
spectrometry in the selected-ion monitoring mode. J.
Chromatogr. B 1996, 682, 55–66.
132. Gioino, G.; Hansen, C.; Pacchioni, A.; Rocca, F.; Barrios, S.M.;
Brocca, E.; Cancela, L.M. Use of high-performance liquid chro-
matography with diode-array detection after a primary drug
screening in patients admitted to the emergency department.
Ther. Drug Monit. 2003, 25, 99–106.
133. Chmielewska, A.; Konieczna, L.; Plenis, A.; Bieniecki, M.;
Lamparczyk, H. Determination of diclofenac in plasma by high-
performance liquid chromatography with electrochemical detec-
tion. Biomed. Chromatogr. 2005, 20, 119–24.
134. Alnouti, Y.; Srinivasan, K.; Waddell, D.; Bi, H.; Kavetskaia, O.;
Gusev, A.I. Development and application of a new on-line SPE
system combined with LC-MS/MS detection for high throughput
direct analysis of pharmaceutical compounds in plasma. J.
Chromatogr. A 2005, 1080, 99–106.
135. Rodriguez, I.; Llompart, M.P.; Cela, R. Solid-phase extraction of
phenols. J. Chromatogr. A 2000, 885, 291–304.
136. Wang, S.P.; Lee, W.T. Determination of benzophenones in a cos-
metic matrix by supercritical fluid extraction and capillary elec-
trophoresis. J. Chromatogr. A 2003, 987, 269–75.
137. Bruzzoniti, M.C.; Sarzanini, C.; Mentasti, E. Preconcentration of
contaminants in water analysis. J. Chromatogr. A 2000, 902,
289–309.
138. Yin, X.-B.; Wang, E. Capillary electrophoresis coupling with elec-
trochemiluminescence detection: a review. Anal. Chim. Acta
2005, 533, 113–20.
139. Wang, J. Electrochemical detection for capillary electrophoresis
microchips: a review. Electroanalysis 2005, 17, 1133–40.
140. Dolnik, V. Wall coating for capillary electrophoresis on
microchips. Electrophoresis 2004, 25, 3589–601.
141. Trojanowicz, M.; Szewczynska, M.; Wcislo, M. Electroanalytical
flow measurements—recent advances. Electroanalysis 2003, 15,
347–65.
142. García, C.D.; Dressen, B.M.; Henderson, A.; Henry, C.S.
Comparison of surfactants for dynamic surface modification of
poly(dimethylsiloxane) microchips. Electrophoresis 2005, 26,
703–9.
143. Ng, J.M.; Gitlin, I.; Stroock, A.D.; Whitesides, G.M. Components
for integrated poly(dimethylsiloxane) microfluidic systems.
Electrophoresis 2002
, 23, 3461–73.
144. Pirogov, A.V.; Shpigun, O.A. Application of water-soluble poly-
mers as modifiers in electrophoretic analysis of phenols.
Electrophoresis 2003, 24, 2099–105.
145. Scampicchio, M.; Wang, J.; Mannino, S.; Chatrathi, M.P.
Microchip capillary electrophoresis with amperometric detection
for rapid separation and detection of phenolic acids. J.
Chromatogr. A 2004, 1049, 189–94.
146. Morales, S.; Cela, R. Highly selective and efficient determination
of U.S. Environmental Protection Agency priority phenols
employing solid-phase extraction and non-aqueous capillary
electrophoresis. J. Chromatogr. A 2000, 896, 95–104.
147. Porras, S.P.; Kuldvee, R.; Palonen, S.; Riekkola, M.L. Capillary
electrophoresis of methyl-substituted phenols in acetonitrile. J.
Chromatogr. A 2003, 990, 35–44.
148. Peng, Y.; Chu, Q.; Liu, F.; Ye, J. Determination of phenolic con-
stituents of biological interest in red wine by capillary elec-
trophoresis with electrochemical detection. J. Agric. Food Chem.
2004, 52, 153–6.
149. Carrasco-Pancorbo, A.; Cerretani, L.; Bendini, A.; Segura-
Carretero, A.; Gallina-Toschi, T.; Fernandez-Gutierrez, A.
Analytical determination of polyphenols in olive oils. J. Sep. Sci.
2005, 28, 837–58.
150. Dabek-Zlotorzynska, E.; Chen, H.; Ding, L. Recent advances in
capillary electrophoresis and capillary electrochromatography of
pollutants. Electrophoresis 2003, 24, 4128–49.
151. Priego Capote, F.; Ruiz Jimenez, J.; de Castro, M.D. Fast separa-
tion and determination of phenolic compounds by capillary
electrophoresis-diode array detection. Application to the charac-
terisation of alperujo after ultrasound-assisted extraction. J.
Chromatogr. A 2004, 1045, 239–46.
152. Klampfl, C.W. Review coupling of capillary electrochromatogra-
phy to mass spectrometry. J. Chromatogr. A 2004, 1044, 131–44.
153. Huck, C.W.; Stecher, G.; Scherz, H.; Bonn, G. Analysis of drugs,
natural and bioactive compounds containing phenolic groups by
capillary electrophoresis coupled to mass spectrometry.
Electrophoresis 2005, 26, 1319–33.
154. Peri-Okonny, U.L.; Kenndler, E.; Stubbs, R.J.; Guzman, N.A.
Characterization of pharmaceutical drugs by a modified non-
aqueous capillary electrophoresis-mass spectrometry method.
Electrophoresis 2003, 24, 139–50.
155. Kannamkumarath, S.S.; Wuilloud, R.G.; Jayasinghe, S.; Caruso,
J.A. Fast speciation analysis of iodophenol compounds in river
waters by capillary electrophoresis-inductively coupled plasma-
mass spectrometry with off-line solid-phase microextraction.
Electrophoresis 2004, 25, 1843–51.
156. Holland, L.A.; Leigh, A.M. Amperometric and voltammetric
detection for capillary electrophoresis. Electrophoresis 2002, 23,
3649–58.
157. Guan, Y.; Chu, Q.; Fu, L.; Ye, J. Determination of antioxidants in
cosmetics by micellar electrokinetic capillary chromatography
with electrochemical detection. J. Chromatogr. A 2005,
1074,
201–4.
158. Kuban, P.; Berg, M.; García, C.D.; Karlberg, B. On-line flow sam-
ple stacking in a flow injection analysis-capillary electrophoresis
system: 2000-fold enhancement of detection sensitivity for prior-
ity phenol pollutants. J. Chromatogr. A 2001, 912, 163–70.
159. Chen, G.; Lin, Y.; Wang, J. Monitoring environmental pollutants
by microchip capillary electrophoresis with electrochemical
detection. Talanta 2006, 68, 497–503.
160. Wang, J.; Chen, G.; Chatrathi, M.P.; Musameh, M. Capillary elec-
trophoresis microchip with a carbon nanotube-modified electro-
chemical detector. Anal. Chem. 2004, 76, 298–302.
161. He, F.Y.; Liu, A.L.; Xia, X.H. Poly(dimethylsiloxane) microchip
capillary electrophoresis with electrochemical detection for rapid
measurement of acetaminophen and its hydrolysate. Anal.
Bioanal. Chem. 2004, 379, 1062–7.
162. Wang, J.; Chen, G.; Chatrathi, M.P.; Fujishima, A.; Tryk, D.A.;
Shin, D. Microchip capillary electrophoresis coupled with a
boron-doped diamond electrode-based electrochemical detector.
Anal. Chem. 2003, 75, 935–9.
163. Deng, G.; Collins, G.E. Nonaqueous based microchip separation
of toxic metal ions using 2-(5-bromo-2-pyridylazo)-5-(N-propyl-
N-sulfopropylamino)phenol. J. Chromatogr. A 2003, 989,
311–16.
164. Wang, J.; Pumera, M.; Chatrathi, M.P.; Escarpa, A.; Konrad, R.;
Griebel, A.; Dorner, W.; Lowe, H. Towards disposable lab-on-a-
chip: poly(methylmethacrylate) microchip electrophoresis
device with electrochemical detection. Electrophoresis 2002, 23,
596–601.
165. Tanyanyiwa, J.; Hauser, P.C. High-voltage capacitively coupled
contactless conductivity detection for microchip capillary elec-
trophoresis. Anal. Chem. 2002, 74, 6378–82.
166. Klett, O.; Nischang, I.; Nyholm, L. Deviceless decoupled electro-
chemical detection of catecholamines in capillary electrophore-
sis using gold microband array electrodes. Electrophoresis 2002,
23, 3678–82.
PHENOLIC COMPOUNDS continued
J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006 ###### J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006
167. Wang, J.; Ibanez, A.; Chatrathi, M.P.; Escarpa, A. Electrochemical
enzyme immunoassays on microchip platforms. Anal. Chem.
2001, 73, 5323–7.
168. O’Neill, A.P.; O’Brien, P.; Alderman, J.; Hoffman, D.; McEnery,
M.; Murrihy, J.; Glennon, J.D. On-chip definition of picolitre
sample injection plugs for miniaturised liquid chromatography.
J. Chromatogr. A 2001, 924, 259–63.
169. Lacher, N.A.; Garrison, K.E.; Martin, R.S.; Lunte, S.M. Microchip
capillary electrophoresis/electrochemistry. Electrophoresis 2001,
22, 2526–36.
170. Hibara, A.; Tokeshi, M.; Uchiyama, K.; Hisamoto, H.; Kitamori,
T. Integrated multilayer flow system on a microchip. Anal. Sci.
2001, 17, 89–93.
171. Tokeshi, M.; Minagawa, T.; Kitamori, T. Integration of a microex-
traction system solvent extraction of a Co-2-nitroso-5-dimeth-
ylaminophenol complex on a microchip. J. Chromatogr. A 2000,
894, 19–23.
172. McEnery, M.; Tan, A.; Glennon, D.; Alderman, J.; Patterson, J.;
O'Mathuna, S.C. Liquid chromatography on-chip: progression
towards a micro-total analysis system. Analyst 2000, 125, 25–7.
173. de Carvalho, R.M.; Kubota, L.T.; Rath, S. Influence of EDTA on
the electrochemical behavior of phenols. J. Electroanal. Chem.
2003, 548, 19–26.
174. LaCourse, W.R.; Modi, S.J. Microelectrode applications of pulsed
electrochemical detection. Electroanalysis 2005, 17, 1141–52.
175. García, C.D.; Henry, C.S. Coupling capillary electrophoresis with
pulsed amperometric detection. Electroanalysis 2005, 17,
1125–31.
176. Kuhnline, C.D.; Gangel, M.G.; Hulvey, M.K.; Martin, R.S.
Detecting thiols in a microchip device using micromolded car-
bon ink electrodes modified with cobalt phthalocyanine. Analyst
2006, 131, 202–7.
177. García, C.D.; Henry, C.S. Direct determination of carbohydrates,
amino acids and antibiotics by microchip electrophoresis with
pulsed amperometric detection. Anal. Chem. 2003, 75, 4778–83.
178. García, C.D.; Ortiz, P.I. Glassy carbon electrodes modified with
different electropolymerized resol prepolymer mixtures for phe-
nol and derivatives quantification. Anal. Sci. 1999, 15, 461–5.
179. Schwarz, M.A.; Galliker, B.; Fluri, K.; Kappes, T.; Hauser, P.C. A
two-electrode configuration for simplified amperometric detec-
tion in a microfabricated electrophoretic separation device.
Analyst 2001, 126, 147–51.
180. García, C.D.; De Pauli, C.P.; Ortiz, P.I. Electrochemical character-
ization of glassy carbon electrodes modified by resol mixtures. J.
Electroanal. Chem. 2001, 510, 115–19.
181. García, C.D.; Henry, C.S. Enhanced determination of glucose by
microchip electrophoresis with pulsed amperometric detection.
Anal. Chim. Acta 2004, 508, 1–9.
182. García, C.D.; Henry, C.S. Direct detection of renal function mark-
ers using microchip CE with pulsed electrochemical detection.
Analyst 2004, 129, 579–84.
183. LaCourse, W.R. Pulsed Electrochemical Detection in High-
Performance Liquid Chromatography; John Wiley & Sons: New
York, 1997.
184. Galeano Diaz, T.; Guiberteau Cabanillas, A.; Mora Diez, N.;
Parrilla Vazquez, P.; Salinas Lopez, F. Rapid and sensitive deter-
mination of 4-nitrophenol, 3-methyl-4-nitrophenol, 4,6-dinitro-o-
cresol, parathion-methyl, fenitrothion, and parathion-ethyl by
liquid chromatography with electrochemical detection. J. Agric.
Food Chem. 2000, 48, 4508–13.
185. Wang, J.; Chatrathi, M.P.; Tian, B. Capillary electrophoresis
microchips with thick-film amperometric detectors: separation
and detection of phenolic compounds. Anal. Chim. Acta 2000,
416, 9–14.
186. García, G.; García, C.D.; Ortiz, P.I.; De Pauli, C.P. Reflectometry
applied to electrochemically generated phenoxy radical adsorp-
tion monitoring. J. Electroanal. Chem. 2002, 519, 53–59.
187. Maluleke, M.A.; Linkov, V.M. Partial electrochemical oxidation of
phenol on ceramic-based flat-sheet type electromembrane reac-
tors. Sep. Sci. Technol. 2003, 32, 377–85.
188. Abaci, S.; Tamer, U.; Pekmez, K.; Yildiz, A. Electrosynthesis of
benzoquinone from phenol on [alpha] and [beta] surfaces of
PbO
2
. Electrochim. Acta 2005, 50, 3655–9.
189. Vandaveer, IV, W.R..; Pasas-Farmer, S.A.; Fischer, D.J.;
Frankenfeld, C.N.; Lunte, S.M. Recent developments in electro-
chemical detection for microchip capillary electrophoresis.
Electrophoresis 2004, 25, 3528–49.
190. Vickers, J.A.; Henry, C.S. Simplified current decoupler for
microchip capillary electrophoresis with electrochemical and
pulsed amperometric detection. Electrophoresis 2005, 26,
4641–7.
191. Guan, Y.; Chu, Q.; Fu, L.; Ye, J. Determination of antioxidants in
cosmetics by micellar electrokinetic capillary chromatography
with electrochemical detection. J. Chromatogr. A 2005, 1074,
201–4.
192. Canals, I.; Bosch, E.; Rosés, M. Prediction of the separation of
phenols by capillary zone electrophoresis. Anal. Chim. Acta
2002, 458, 355–66.
193. Ding, Y.; García, C.D. Pulsed amperometric detection with
poly(dimethylsiloxane)-fabricated capillary electrophoresis
microchips for the determination of EPA priority pollutants.
Analyst 2006, 131, 208–14.
194. Boyce, M.C. Simultaneous determination of antioxidants, preser-
vatives and sweeteners permitted as additives in food by mixed
micellar electrokinetic chromatography. J. Chromatogr. A 1999,
847, 369–75.
195. Delgado-Zamarreno, M.M.; Sanchez-Perez, A.; Gonzalez Maza, I.;
Hernandez-Mendez, J. Micellar electrokinetic chromatography with
bis(2-ethylhexyl)sodium sulfosuccinate vesicles: Determination of
synthetic food antioxidants. J. Chromatogr. A 2000, 871, 403–14.
196. Guan, Y.; Chu, Q.; Fu, L.; Wu, T.; Ye, J. Determination of phe-
nolic antioxidants by micellar electrokinetic capillary chromatog-
raphy with electrochemical detection. Food Chem. 2006, 94,
157–62.
197. García, C.D.; Engling, G.; Herckes, P.; Collett, Jr., J.L.; Henry, C.S.
Determination of levoglucosan from smoke samples using
microchip capillary electrophoresis with pulsed amperometric
detection. Environ. Sci. Technol. 2005, 39, 618–23.
198. García, C.D.; Henry, C.S. Comparison of pulsed electrochemical
detection modes coupled with microchip capillary electrophore-
sis. Electroanalysis 2005, 17, 223–9.
199. Weinberger, D.R. Practical Capillary Electrophoresis; Academic
Press: San Diego, 2000.
200. Tonin, F.G.; Jager, A.V.; Micke, G.A.; Farah, J.P.; Tavares, M.F.
Optimization of the separation of flavonoids using solvent-mod-
ified micellar electrokinetic chromatography. Electrophoresis
2005, 26, 3387–96.
201. Jager, A.V.; Tonin, F.G.; Tavares, M.F. Optimizing the separation
of food dyes by capillary electrophoresis. J. Sep. Sci. 2005, 28,
957–65.
202. Roman, G.T.; Hlaus, T.; Bass, K.J.; Seelhammer, T.G.; Culbertson,
C.T. Sol-gel modified poly(dimethylsiloxane) microfluidic
devices with high electroosmotic mobilities and hydrophilic
channel wall characteristics. Anal. Chem. 2005
, 77, 1414–22.
203. Roman, G.T.; McDaniel, K.; Culbertson, C.T. High efficiency
micellar electrokinetic chromatography of hydrophobic analytes
on poly(dimethylsiloxane) microchips. Analyst 2006, 131,
194–201.
PHENOLIC COMPOUNDS continued
J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006 ###### J. CAP. ELEC. AND MICROCHIP TECH. 009 : 5/6 2006
