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Effect of various storage periods on recovery (%) of pharmaceuticals, pesticides, hormones (synthetic and natural estrogens and progestogens) dissolved in surface water at 100 ng l-1 Level. The error bar lengths represent the relative standard deviations on mean recovery (recovery for three replicates). Bars with the same letters are not statistically different p > 0.05 level using a Tukey's-b post hoc test.
Source publication
Monitoring and analysis of trace contaminants such as pharmaceuticals and pesticides require the preservation of the samples before they can be quantified using the appropriate analytical methods. Our objective is to determine the sample shelf life to insure proper quantification of ultratrace contaminants. To this end, we tested the stability of a...
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Citations
... While such comprehensive workflows have many benefits, they offer challenges to food safety chemists who are tasked with developing such testing methods. Among these challenges are chemical incompatibility and degradation (1) which are characteristic of many pesticides (2). ...
Background
In response to the growing global need for pesticide residue testing, laboratories must develop versatile analytical methods and workflows to produce scientifically sound results. One of the many challenges faced by food chemists is acquiring suitable pesticide certified reference materials (CRMs) to calibrate analytical equipment, monitor method performance and confirm the identity and concentration of hundreds of pesticide residues in food samples. CRM producers invest considerable resources to ensure the stability of their products.
Objective
To present proper CRM handling and storage practices as guidance to ensure stability based on the results of several multiresidue pesticide stability studies.
Method
The open ampoule and combined multiresidue mix studies were conducted under controlled conditions. New ampoules containing multiresidue pesticide CRM mixtures were opened and compared to previously opened ampoules at multiple intervals while stored under freezing and refrigerated temperatures. Both LC and GC amenable pesticides (>200 residues) were combined and stored under typical laboratory conditions. Studies were performed with and without celery matrix.
Results
The open ampoule study showed high levels of stability for all mixtures. All GC residues remained stable over the duration of the experiment. A week after opening LC multiresidue pesticide mixtures showed minor degradation. After combination of the multiresidue pesticide mixtures, degradation occurred rapidly for both the GC and LC mixtures.
Conclusions
Multiresidue pesticide mixtures are stable as ampullated until they are opened. Once the contents of a kit were opened and combined, decreasing stability was observed over time. This was true for both the LC and GC kits. Working mixtures of CRMs for instrument calibration should be made daily.
Highlights
This paper shows a novel approach for measuring stability of CRM mixes. In-depth analysis of multiresidue pesticide mixtures and the stability that can be expected before and after mixing under typical storage conditions is described.
... In particular, the physical and chemical properties of pesticides, such as saturated vapour pressure and solubility, directly affect storage stability. Compounds with low vapour pressure and moderate solubility (up to 40 mg/L) are stable, while compounds with high solubility (up to 700 mg/L) or high vapour pressure are unstable [34][35]. Generally, at low concentrations, the half-life of pesticides becomes more dependent on storage conditions (pH, exposure to light, and temperature) [36]. ...
In this study, 9 active substances that could be analysed by Gas Chromatography-Mass Spectrometer (GC/MS) were used. Changes in these pesticide residues were determined after strawberries were washed, pasteurized, stored in cold and washed on different days. In addition, strawberry puree was stored at -18±2ºC and pasteurized puree was stored at different temperatures. The highest and lowest processing factors in the pasteurization process were determined in tebufenpyrad (Pf:1.20) and tetraconazole (Pf:0.81), respectively. During cold storage, kresoxim-methyl degradation was found statistically significant (p
... Antidepressants such as fluoxetine and citalopram have the potential to adversely influence algal production, thereby upsetting the ecosystem balance in waterbodies (Wu et al., 2017). Antidepressant have also been discovered in treated and untreated wastewater in several countries (Aboulfadl et al., 2010;Wu et al., 2017). Although, their concentration varies from different regions. ...
Pharmaceuticals in wastewater are rapidly becoming new emerging pollutants, affecting humans and the aquatic ecosystem, and can go undetected due to their microscopic nature. Adsorption proves to be a promising technology for the removal of pharmaceuticals from effluent wastewater owning to its low cost, flexibility, and renewability. Adsorbents are porous materials such as silica, clay, resins, and carbon-based materials (e.g., biochars, carbon nanotubes, and activated carbon) often used to remove pharmaceutical micropollutants during adsorption. Among them biochar is an emerging, cost-effective, and eco-friendly sorbent. Modeling methods such as linear correlativity and multilinear regressions, are often employed to explain the adsorption mechanism, however they show limited accuracy and applicability. On the contrary, data driven machine learning (ML) methods is a powerful tool that could be used to study the complex relationship between adsorption performances and biochar properties. This review provides an overview of recent advances in the use of machine learning (ML) methods to explore the field of pharmaceutical adsorption onto biochar. An introduction to different ML algorithms and their advantages and limitations is provided. Furthermore, the challenges and future prospects of ML applications to study the adsorption mechanism is outlined.
... Storage conditions were investigated with different preservative agents in surface water samples spiked at 100 ng L − 1 with targeted analytes and stored at 4 • C for a period of 21 days. Formaldehyde was tested at 1% (v/v) based on a previous study [41]. Sodium thiosulfate was also tested (70 mg L − 1 ) based on previous studies for drinking water and wastewater effluents with residual chlorine [42,43]. ...
EPA method 539.1 recently introduced an expanded list of priority endocrine-disrupting compounds (EDCs), some of which were also included in the Unregulated Contaminant Monitoring Rule 3 (UCMR3). Though standardized methods are available for drinking water, analysis of steroid hormones and bisphenol A (BPA) at the ultra-trace level remains challenging. This study set out to evaluate the suitability of automated off-line solid-phase extraction (SPE) liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) for the determination of EPA-priority EDCs in environmental water matrixes (tap water, surface water, and wastewater influents and effluents). The target molecules included 14 steroid hormones (altrenogest, androstenedione, equilenin, equilin, α-estradiol, β-estradiol, estriol, estrone, ethinylestradiol, levonorgestrel, medroxyprogesterone, norethindrone, progesterone, testosterone) and BPA. Factors that may influence the analytical performance were assessed. This involved, for instance, testing combinations of SPE materials from different brands and protocol variations. Several materials presented absolute extraction efficiencies in acceptable ranges. Initial sample pH, nature of reconstitution medium, and mobile phase salt concentration were among the potential factors affecting analyte signal. Storage conditions (different preservative agents) possibly exerted the strongest influence, in agreement with the literature. Limits of detection were in the range of 0.03–0.5 ng/L in drinking water, 0.1–0.5 ng/L in surface water, and 0.16–1 ng/L in wastewater. Method validation also involved testing linearity, accuracy, and precision in reagent water and matrix-matched extracted calibrants. The method was applied to field-collected water samples in Eastern Canada. Summed EDC concentrations remained low in tap water (<LOQ–0.92 ng/L), while higher detection frequencies and contamination levels were reported in riverine surface waters (2.6–37 ng/L) and municipal wastewaters (10–424 ng/L).
... After collecting the water, the bottles were transferred using cooled transport and stored immediately at 4 C until analyses could be established (Gawlik et al., 2012). When storage more than 10 days was inevitable, bottles were frozen promptly ensuring the stability of the samples (Aboulfadl et al., 2010) and analysed within 8 weeks starting from the moment of sampling. ...
Pesticides are broadly utilized in crop cultivation and could end up in wastewater of vegetable- and potato companies during water-consuming processing steps. To gain insight into the presence of pesticide residues in (waste)water of these industries, water was analysed and monitored from three vegetable- and two potato processing companies in Belgium. Samples were collected during one year of water before and after primary/secondary treatment (i.e. influent and effluent) and after tertiary treatment. Next to water, also (processed) carrot and potato products were analysed. Results show that boscalid (maximum: 18.32 μg/L) and terbuthylazine (maximum: 87.99 μg/L) are predominantly present in the vegetable industry and chlorpropham (maximum: 8.80x10⁶ μg/L) and terbuthylazine (maximum: 3.37x10⁵ μg/L) in the potato industry. The conventional treatment techniques seem to be insufficient for the removal of pesticides. Concentrations were even higher in the effluent than in the influent. Also, tertiary treatment techniques as ultra-filtration and reverse osmosis fail to reduce all pesticides below the European potable water limit of 0.1 μg/L. To meet this standard, the development and validation of new removal techniques are essential. Regarding product samples, almost no pesticide residues exceeded the MRL. Chlorpropham concentrations were statistically confirmed to be higher in potatoes and wastewater sampled when stored potatoes are processed.
... Daily composite samples consisted of 4 aliquots per day (collected every 6 h by the autosampler) of about 6.5 mL each; weekly composite samples consisted of 2 aliquots per day (collected every 12 h for 7 days) of about 1.8 mL each. Aliquots were delivered through a glass-fiber 0.7-μm, 25-mm syringe filter (Whatman) into a 40-mL vial containing 3 mL methanol solution, to act as a preservative (Aboulfadl et al., 2010). The number of successful daily and weekly composite samples collected at each of the 7 Midwestern sites ranged from 56 to 88 for daily samples, for a total of 513 daily samples, and from 1 to 7 for weekly samples for a total of 35 weekly samples. ...
Transient, acutely toxic concentrations of pesticides in streams can go undetected by fixed-interval sampling programs. Here we compare temporal patterns in occurrence of current-use pesticides in daily composite samples to those in weekly composite and weekly discrete samples of surface water from 14 small stream sites. Samples were collected over 10-14 weeks at 7 stream sites in each of the Midwestern and Southeastern United States. Samples were analyzed for over 200 pesticides and degradates by direct aqueous injection liquid chromatography with tandem mass spectrometry. Nearly 2 and 3 times as many unique pesticides were detected in daily samples as in weekly composite and weekly discrete samples, respectively. Based on exceedances of acute-invertebrate benchmarks (AIB) and(or) a Pesticide Toxicity Index (PTI) >1, potential acute-invertebrate toxicity was predicted at 11 of 14 sites from the results for daily composite samples, but was predicted for only 3 sites from weekly composites and for no sites from weekly discrete samples. Insecticides were responsible for most of the potential invertebrate toxicity, occurred transiently, and frequently were missed by the weekly discrete and composite samples. The number of days with benthic-invertebrate PTI ≥0.1 in daily composite samples was inversely related to Ephemeroptera, Plecoptera, and Trichoptera (EPT) richness at the sites. The results of the study indicate that short-term, potentially toxic peaks in pesticides frequently are missed by weekly discrete sampling, and that such peaks may contribute to degradation of invertebrate community condition in small streams. Weekly composite samples underestimated maximum concentrations and potential acute-invertebrate toxicity, but to a lesser degree than weekly discrete samples, and provided a reasonable approximation of the 90th percentile total concentrations of herbicides, insecticides, and fungicides, suggesting that weekly composite sampling may be a compromise between assessment needs and cost.
... Water pH and temperature were measured (Table S3) and a 500 mL water sample taken, acidified (0.1% HCl) and T.H. Miller, et al. Environment International xxx (xxxx) xxx-xxx stored at 4°C for a maximum of 4 days prior to analysis to improve stability of analytes as shown in previous studies (Baker and Kasprzyk-Hordern, 2011;Aboulfadl et al., 2010). ...
Multiple classes of environmental contaminants have been found in aquatic environments, globally. Understanding internalised concentrations in the organism could further improve the risk assessment process. The present study is concerned with the determination of several contaminant classes (107 compounds) in Gammarus pulex collected from 15 sites covering 5 river catchments across Suffolk, UK. Quantitative method performance was acceptable for 67 compounds including pharmaceuticals, pesticides, illicit drugs and drugs of abuse. A total of 56 compounds were detectable and ranged from
... 30 The physical and chemical properties of pesticides, such as saturated vapor pressure and water solubility, can directly affect the stability of pesticides. 31,32 ...
Corn flour has been stored at different moisture content (without and with 10 % water) and temperatures (–20, 4 and 25 °C). A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) method was applied to determine the degradation rate of five common pesticides (imidacloprid, carbendazim, triadimefon, acetochlor and metolachlor) during the stored process using high-performance liquid chromatography with a diode array detector and gas chromatography with an electron capture detector. The results showed that there was almost no degradation on five pesticides at –20°C in corn flour whether with or without water, and the half-life was 69.3–693.2 days. The degradation rate ranged from 1.7 to 7.8 % after ten days of application. Under 25°C and 10 % moisture content, the half-life was sharply reduced to 5.8–14.4 days. Under this condition, the degradation rate ranged from 40.6 to 68.4 % after ten days of application, and the sequence from high to low of the five pesticides. The degradation rates were as follows: carbendazim, imidacloprid, acetochlor, metolachlor and triadimefon. Therefore, low temperature and drying were beneficial to the storage of corn flour, but unfavorable to the degradation of pesticides in corn flour.
... Filtrates were kept at 4°C and analyzed within 24 h to minimize the risk of biodegradation. No preservatives were added because filtered samples were shown to remain unchanged for at least 3 days (Aboulfadl et al., 2010). Water samples were pre-concentrated by online SPE, followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) for separation and quantification. ...
Extensive environmental monitoring was conducted in an urban river impacted by multiple combined sewer overflows (CSOs) and wastewater treatment plant (WWTP) discharge points. Temporal and spatial distributions of dissolved and particulate steroids (progesterone (Prog), testosterone (Testo), medroxyprogesterone (MDRXY-Prog), levonorgestrel (Levo), norethindrone (Nore), estrone (E1), estradiol (E2), estriol (E3), and 17α-ethinylestradiol (EE2)) were investigated in sewage, WWTP effluents, receiving river water and sediments, and in drinking water plant (DWP) intakes. Steroids were detected in both dissolved and particulate phases with mean concentrations from 21ngL-1 to 389ngL-1 in raw sewage and from 10ngL-1 to 296ngL-1 in treated wastewater. The particle-associated steroids represented 0-82% of their total concentration as some steroids like E1 and E3 were detected only in the dissolved phase while MDRXY-Prog (81%), Nore (71%), and EE2 (>75%) were primarily detected in the particulate phase. Particle-associated steroids were detected in spring samples from river water with mean concentrations ranging from 5.4ngL-1 to 35.7ngL-1 compare to 3ngL-1 to 6.8ngL-1 in summer samples. Levels of particle-associated Testo, Nore, E2 and Levo in DWP intakes (406.2-13,149.1ngg-1) were similar to those found in raw sewage (336.6-7628.8ngg-1), indicating their persistence in the suspended phase from discharge points. Total steroids measured in sediments were in the range of 7-1213ngg-1, 5-25ngg-1, and 22-226ngg-1 in autumn, spring, and summer, respectively. Our findings confirm the presence and seasonal variation of a mixture of particle-associated steroids in drinking water sources. The presence of high concentrations of a mixture of particle-associated steroids in DWP intakes highlight the need for highly effective particle-removal processes to eliminate these recalcitrant compounds during drinking water production. Finally, the detected concentrations raise concerns about their potential environmental effects.
... The utility of this work is evident in studies requiring storage of POCIS before analysis [9,10]. There have been studies on the stability of pharmaceutical and pesticide residues in surface waters stored refrigerated [11] and frozen in raw wastewater samples [12] and in preserved or pretreated (e.g., addition of ethylenediaminetetraacetic acid) water samples [13]. A more detailed review of earlier works on aqueous sample storage stability can be found elsewhere [7]. ...
... A more detailed review of earlier works on aqueous sample storage stability can be found elsewhere [7]. Briefly, these studies generally observed significant losses for several analytes over relatively short time periods, for instance 10 d [11], 85 d [13], and 120 d [12]. Clearly, sequestration of analytes onto a solid sorbent before freezing, be it a passive sampling device or solid phase extraction cartridge, can represent the most effective storage and archival option. ...
In the present study, we report the freezer storage stability of pharmaceuticals and pesticides for the organic-diffusive gradients in thin-films (o-DGT) passive sampler and the polar organic chemical integrative sampler (POCIS). The average change on o-DGT after approximately 18 mo was 9 ± 9% across 30 compounds. For POCIS, the average change after approximately 6 yr was 14 ± 14% for the same compounds. Our data suggest that analytes stored on these samplers are stable and appropriate for archival purposes.
