Six arsenic species [arsenate, arsenite, arsenocholine, arsenobetaine, monomethyl arsonic acid, and dimethyl arsinic acid] present in human urine were determined using ion-exchange chromatography combined with inductively coupled plasma mass spectrometry (IC-ICP-MS). Baseline separation was achieved for all six species as well as for the internal standard (potassium hexahydroxy antimonate V) in a single chromatographic run of less than 30 min, using an ammonium carbonate buffer gradient (between 10 and 50 mM) at ambient temperature, in conjunction with cation- and anion-exchange columns in series. The performance of the method was evaluated with respect to linearity, precision, accuracy, and detection limits. This method was applied to determine the concentration of these six arsenic species in human urine samples (n = 251) collected from a population-based exposure assessment survey. Method precision was demonstrated by the analysis of duplicate samples that were prepared over a 2-year analysis period. Total arsenic was also determined for the urine samples using flow injection analysis coupled to ICP-MS. The summed concentration of the arsenic species was compared with the measured arsenic total to demonstrate mass balance.

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Several sample preparation techniques were investigated to maximize the efficiency of arsenic species extraction from food composites. The optimized method includes lyophilization of food followed by prewashing with acetone and extraction by sonication with 50/50 methanol/water. Six arsenic species were separated and quantitated using an ammonium carbonate buffer system by ion exchange chromatography coupled to inductively coupled plasma mass spectrometry. The performance of the method for speciated arsenic components was evaluated using a matrix containing high fat food composite fortified with arsenic species. A certified reference material, dogfish muscle, was used to evaluate extraction methods for total arsenic content in food composites. More than 200 food composite samples were analyzed during an 18 month period, demonstrating the reliability of the analytical method over a long time period.

A polymer blend formulation originally patented by the National Aeronaticautical and Space Administration (NASA) has been modified for use in spectroscopic sensing. The cured polymer blend is a mixture of poly(acrylic acid) in glutaraldehyde cross-linked poly(vinyl alcohol). We have optimized the composition and the casting of the blend for optical sensing. The blend has clear ultraviolet (UV) and visible spectral regions for direct spectroscopic sensing, and it is an excellent absorber of many inorganic and organic cations from aqueous solution. The kinetics of the uptake of [Ru(BiPy)3]2+ and rhodamine 620 are presented as examples of complex ion preconcentration by the blend. With only the polymer blend directly applied as a fiber-optic cladding, aqueous Cu2+ ion can be detected as low as 10−6 M by using a light-emitting diode at 810 nm as a light source. A blend-clad fiber-optic sensor can be regenerated at least 25× without significant deterioration. The polymer blend can also trap hydrophobic compleximetric reagents added during the curing of the cross-linked blend. A prototype compleximetric dye-based evanescent-wave fiber-optic sensor using 1-(2'-pyridylazo)-2-naphthol was developed to detect aqueous Co2+ with a red HeNe laser light source. The Co2+ ion could be detected as low as 10−7 M.