Pia Kochifas's research while affiliated with University of Concepción and other places

The determination of tin by FAAS is widely recognized as a difficult task in atomic spectrometry because of low sensitivity, poor detection limits and important interferences. In this work a new sample introduction system, the subcritical fluid nebulizer (ScFN) combined with the flame furnace-atomic absorption spectrometry (FF-AAS) was applied for improving the determination of inorganic tin in aqueous solutions. Online preconcentration of tin as Sn-PDC complex was carried out in a HPLC-guard cartridge (5mm length, 2mm diameter) filled with C-18 coated monolithic silica having an absorption capacity of 2.5μg of tin. For preconcentration optimized conditions were achieved at 0.015% (m/v) of APDC and pH5 obtaining a preconcentration factor of 17 using 2.5 mL of sample volume. The elution was done by means of subcritical liquid carbon dioxide and methanol with a flow rate of 1.5 L min-1 which was directly introduced as a dry aerosol into the flame furnace where tin complexes are vaporized and atomized. Applying ScFN-FF-AAS the detection and quantification limits for tin in water were 0.008 mg L-1 and 0.024 mg L-1, respectively, increasing the power of detection in 325 times compared to the conventional detection limits obtained by flame atomic absorption spectrometry. The precision at 1 mg L-1 was 1.5% expressed as RSD (N=10). Tin was determined in samples of gunshot residues generated by firing four ammunition brands. The concentrations fluctuated between 52 and 151 μg L-1.

In this study, the photocatalytic oxidation of hazardous arsenite (As(III)) to arsenate (As(V)) and the sequential removal of arsenate from aqueous solution by liquid-phase polymer-based retention (LPR) were investigated. The photocatalytic oxidation of arsenite was performed using TiO2 (P25 Degussa, Germany) under UV-A light. The optimal photocatalytic conditions to oxidize 10 mg L−1 of arsenite solution were achieved using a 0.5 g L−1 of catalyst at a pH value of 2. The As(III) oxidation reached 100% after 30 min of illumination with UV-A light. A water-soluble polymer containing quaternary ammonium groups, poly(3-acrylamidopropyl)trimethylammonium chloride (P(ClAPTA)), was used as an extracting reagent in the LPR process. To obtain the optimized conditions, the removal experiments were performed at various polymer : As(V) molar ratios using 10 mg L−1 of arsenate solutions. After the oxidation of As(III) to As(V), the removal of arsenate by P(ClAPTA) was obtained in a 99% yield using a 20 : 1 polymer : As(V) molar ratio at a pH value of 9. The results demonstrate that the combination of these methods is highly useful for potential applications related to the treatment of wastewater contaminated with As(III). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40871.