| 摘要 |
The essence of the new technique of arsenic hydriding and lead and cadminum preconcentration with increased sensitivity of analisis of foods and drinking water is the addition of the catalysts in a solution, for exciting plasma-chemical titrations of traces of arsenic and lead and cadmium deposited in copper/tin alloy on the platina cathode during electrolytically generating of hydrogen. The new technique enables the same efficiency of hydriding of arsenic in prepared food sample solution and in model solution. The technique enables the analysis with atomic absorption spectrophotometry (AAS) of the most complex viands, based on vegetable oils and margarines, after 7-10 of electrolysis, with detection limits for arsenic 0,002 mg/l. It corresponds to the detection limit for AAS method with chemical hydriding with sodium tetrahydroborate. This technique can be used instead of chemical hydriding of arsenic with zinc, for achieving increased sensitivity of the Gutzeit method. Also it can be used instead of chemical hydriding for achieving increased sensitivity of spectrophotometrically, detection of traces of arsenic with diethyl-dithiocarbamate, as for increasing sensitivity of electrochemical stripping analysis (ESA). The preconcentration of solution after arsenic analysis by dissolving of cathodic deposite in less volume for one order of magnitide than volume of solution prepared for a electrolysis, enables increased sensitivity of AAS and also increased sensitivity of ESA method of analysis. The degree of the simultaneous preconcentration of lead 6,3 and of cadmium 2,7 from the same solution enables the decreasing of the detection limit of standard flame AAS method of analysis of food samples from 0,1 to 0,02 mg/l for lead, and from 0,006 to 0,002 mg/l for cadmium. |
