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Information on the worldwide occurrence of groundwater pollution by arsenic, the ensuing health hazards, and the debatable government regulations of arsenic in drinking water, is presented. Diagnostic identification of arsenic, and methods to eliminate it from water are also discussed.

We describe a disposable electrochemical immunosensor diagnosis device that integrates the immunochromatographic strip technique with an electrochemical immunoassay and exploits quantum dot (QD, CdS@ZnS) as labels for amplifying signal output. The device takes advantage of the speed and low cost of the conventional immunochromatographic strip test and the high sensitivity of the nanoparticle-based electrochemical immunoassay. A sandwich immunoreaction was performed on the immunochromatographic strip, and the captured QD labels in the test zone were determined by highly sensitive stripping voltammetric measurement of the dissolved metallic component (cadmium) with a disposable screenprinted electrode, which is embedded underneath the membrane on the test zone. The new device coupled with a portable electrochemical analyzer shows great promise for in-field and point-of-care quantitative testing of disease-related protein biomarkers. The parameters (e.g., voltammetric measurement of QD labels, antibody immobilization, the loading amount of QD--antibody, and the immunoreaction time) that govern the sensitivity and reproducibility of the device were optimized with IgG model analyte. The voltammetric response of the optimized device is highly linear over the range of 0.1-10 ng m[L.sup.-1] IgG, and the limit of detection is estimated to be 30 pg m[L.sup.-1] in association with a 7-min immunoreaction time. The detection limit was improved to 10 pg m[L.sup.-1] using a 20-min immunoreaction time. The device has been successfully applied for the detection of prostate-specific antigen (PSA) in human serum sample with a detection limit of 20 pg m[L.sup.-1]. The results were validated by using the commercial PSA enzyme-linked immunosorbent assay kit and showed high consistency. The new disposable electrochemical diagnosis device thus provides a rapid, clinically accurate, and quantitative tool for protein biomarker detection.

A new approach to the measurement of solubilities in supercritical CO(sub 2) is reported, utilizing laser-induced fluorescence. This selective technique was found to be capable of rapid multipoint solubility measurements with high sensitivity (10(super -9) M). The sensitivity enables measurements to be performed with small amounts of analytes and at low pressure, 80-130 atm, typically below the range of other methods. Four uranyl complexes were investigated using this method, UO(sub 2)(TTA)(sub 2)*H(sub 2)O, UO(sub 2)-(TTA)(sub 2)*TBP, UO(sub 2)(TTA)(sub 2)*TOPO, and UO(sub 2)(NO(sub 3))(sub 2)*2TBP (where TTA = thenoyltrifluoroacetone, TBP = tributyl phosphate, and TOPO = trioctyl phosphine oxide). Comparison with solubility data previously obtained with UV-visible spectroscopy shows good agreement between the techniques. We have shown that the Chrastil solubility equation is equally valid at lower ScF densities, and consequently, solubility values determined at high pressures can be extrapolated to the low-pressure regions and vice versa for solid materials.

Researchers from the University of Idaho investigated the relative resistance of positional isomers of polychlorinated biphenyls toward reductive dechlorination by zerovalent iron and pressurized hot water.

Time-resolved laser-induced fluorescence has been shown to be effective for on-line measurement of uranyl chelates in supercritical carbon dioxide. Quenching and other factors affecting the method's accuracy were identified and quantified to allow for accurate measurements under variable supercritical fluid conditions. The method was applied to the kinetic analysis of uranium extraction from acidic solutions with tributyl phosphate modified supercritical carbon dioxide.

Research has been conducted on the alpha particle emitters. The design of ionophores derived from calix[4]arene to have selectivity for Ra (super)2+ over the lighter alkaline earth metal ions is described.

Uranyl and Th(IV) ions dissolved in aqueous solution or adsorbed on solid materials were shown to be capable of being effectively extracted by methanol-modified supercritical CO2 containing a fluorinated beta-diketone. The extraction of uranyl and Th(V) ions from solid materials can likewise be done using neat CO2 that contains a binary mixture of TBP and HFA, TTA or FOD. This method was also demonstrated for extracting uranyl ions from mine waters and mine-water-contaminated soil samples.

Dissolved arsenic concentrations in ground water from three wells located in the Blackfoot disease (BFD) area in Taiwan were determined to examine the link between BFD and consumption of water with high arsenic content. Results showed that the BFD area had 671 plus-or-minus 149 micrograms total dissolved arsenic/liter of water on the average. In contrast, wells outside the BFD area had about 0.7 micrograms total dissolved arsenic/liter of water. Dissolved arsenic species come in two forms, one with molecular mass less than 1,000 daltons and another with molecular mass greater than 100,000 daltons. Arsenic speciation and the possible cause of BFD are discussed.