Abstract: Sensor film materials were prepared by mixing an acetonitrile solution of polyoxyethylene with a solution of Zn, Ni or Cu trifluorimethansulfonate in the same solvent, casting the mixture on a Teflon dish (i.d. 100 mm) and allowing the solvent to evaporate. The films were dried in vacuo for 24 h, and sensor cells were constructed by compressing polymeric membranes on to discs of the corresponding metal (i.e., Zn, Ni or Cu; prepared by compacting 1 g of powdered metal) and, finally, sputter-depositing a thin-film (25 nm thick) of Au on to the polymer film. Of the three sensor types evaluated, the Zn-based sensor exhibited the best sensitivity. Under optimum gas flow conditions (28 mL min-1), calibration graphs were rectilinear from 0.02 to 1 ppm of NO2. Response time is ~3 s but recovery after exposure to NO2 take ~3 min. Au/poly(ethylene oxide)nM(CF3SO3)2/M (M = Zn, Cu, Ni) galvanic gas sensors, consisting of a disk 13 mm in diameter and 1.1 mm thick, have been developed by using a polymeric electrolyte film (0.1 mm thick). The polymeric films are made by mixing with an acetonitrile solution both M(CF3SO3)2 and poly(ethylene oxide) (MW ≈ 6 x 10^5). The working electrode (25 nm thick) is made by sputtering gold in an argon atmosphere. Of the three kinds of sensors, the zinc one (n = 55) shows the greatest sensitivity. For the zinc cell, the max. response appears within 3 s after the sample (2.6 mL) is injected into the nitrogen carrier stream, flowing at a rate of 28 mL min-1; the response returns to the baseline within 3 min at the longest. The maximum current flowing in the external circuit is linearly related to the concentration of NO2 in the range 0.02-1 ppm at ambient temperature.

Abstract: A flow-through cell is described for use in both flow injection analysis and HPLC. The carrier solution was 0.2 M NH4OH - NH4Cl buffer (pH 9.5) - 0.5% methanol - 0.5 mM CoCl2, and analysis by HPLC was on a column (25 cm x 4.6 mm) of C18 with a mobile phase similar to the carrier, but with 0.5 mM Na trichloroacetate instead of CoCl2; this system could separate several disulfides. The detection cell contained a dropping-Hg working electrode, a Pt auxiliary electrode and SCE. Differential-pulse polarography of four compounds showed that the catalytic (Brdicka) currents occurred at peak potentials from -1.5 to -1.65 V. With use of 10 µL samples, the detection limit in HPLC was 0.1 mM of dithiodiacetic acid.

Abstract: Potassium peroxodisulfate (14 g 1-1, 25 ml) has been observed to readily oxidize water under UV irradiation (30W mercury arc tube), even at room temperature. The reaction is complete in 20 min, producing oxygen in stoichiometric amounts. The reaction was applied to pretreatment for the determination of total mercury by cold vapor atomic absorption spectrometry (AAS). The response of mercury(II) chloride by the UV irradiation method was higher than that by the standard permanganate method (95°C, 2 h). The conversion efficiency of mercury by the UV irradiation method, the standard method and by non-treatment was found to be 100, 93.6 and 85.0%, respectively. The study is also applied to methylmercury, ethylmercury and phenylmercury chlorides.