The determination of copper, iron and nickel in edible oils was carried out using emulsion sample preparation followed by analysis by ICP-AES. Response surface methodology was applied in order to find the optimum emulsion and surfactant concentrations. The optimum amount of oil in the emulsion was in the range ca. 2-35% in most of the surfactants studied, except for Triton X-100, which showed a maximum response above 35% oil. The surfactant concentration in the emulsion varied between 0.5 and 9%. Good agreement was found between calibration curves for emulsified aqueous standards solutions and oil-in-water emulsions for most elements studied with Tween 80, ethoxynonylphenol and Triton X-100. The best agreement for all elements was shown when Tween 80 was used. Hence emulsified aqueous standard solutions could be used for the determination of these elements in emulsified edible oil samples using ICP-AES. Recoveries ranged from 90 to 110% for most of the elements studied, with relative standard deviations lower than 8%. the use of surfactants to enhance the sample transport process.

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A full experimental design at two levels is applied for the estimation of the significance of select factors that may influence the ion chromatography (IC) determination of F-, Cl-, Br-, NO(-)3, SO(-2)4, and PO(-3)4 in serum samples. The factors studied are various sample deproteinization procedures, eluent composition, and flow rates. Deproteinization using either acetonitrile-NaOH or ultrafiltration can be used in order to obtain a significant protein removal before IC analysis; however, the former is recommended because it is less time-consuming and cheaper. Better resolution is obtained when a sodium hydroxide solution is used as the eluent. There is no influence of the sample's deproteinization procedures on the chromatographic resolution.

Hydrochloric acid was measured in Parupa (5 • 41 N; 61 • 33 W), Canaima National Park, a pristine region located in the southern part of Venezuela, during January and September 2000. During both periods the HCl concentration was quite variable, with relatively higher levels during September and an overall median value of 37 pptv. An analysis of possible sources suggests that the photo-oxidation of chlorocarbons should be a significant source of HCl at the Parupa site.

Solid state surface phases formed on pyrolytic graphite platforms during the atomization of vanadium in ETAAS have been characterized by means of X-ray photoelectron spectroscopy. Vanadium carbide V8C7, usually described...