Study On Determination Of Chromium In Soil By Spectrophotometry

The solution of National level standard samples GBW07403 (GSS-3),GBW07405 (GSS-5),GBW07407 (GSS-7),GBW07424 (GSS-10),GBW07428 (GSS-14),GBW07429 (GSS-15) and a series of soil sample have been prepared by the acid dissolved method and the alkali fu- sed method.The main results are obtained as follows:The optium condition of the solution was prepared with the national level standard samples GBW07403 (GSS-3),the optimum add-on of the concentration of sulfuric acid 2mol/L was 5.0mL,the optimum color time was 10min, the optimum reaction temperature was indoor temperature,the optimum concentration of indicator 1,5-Diphenylcarbohydrazide was mass fraction 0.2% and the optimum add-on was 5.0mLwh- en the add-on of the solution was 5.0mL.The correlation coefficient was obtained through wo- rk curve for 0.99994.The detection limit was obtained through the blank experiment for 10×10-6 with the population chromium detected requirements of geochemical analysis.The relative standard deviation was obtained through the precision experiments for 3.25% with the solution was prepared with the national level standard samples GBW07403 (GSS-3),so this method has high precision.The recovery was obtained through the precision join R M experi- ments for 94.5～102.0% with the solution was prepared with the national level standard sam- ple GBW07403 (GSS-3), GBW07405 (GSS-5), GBW07407 (GSS-7), GBW07424 (GSS-10), GBW07428 (GSS-14),GBW07429 (GSS-15),so this method has high accuracy.The cationic interference was masked by Cation exchange resin.The effects of interference ion was very well confirmed by tracer elements.The alkali fused method was more suitable than the acid dissolved to the analysis of chromium because it is difficult to control the condition of the reaction of the acid dissolved,through the analysis of comparative experiments.This method has better accurate results compared with the ICP-AES method and the Flame atomic absorption spectrometry. The determination of chromium in soil by spectrophotometry may have a good application.