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铬的光度法有二甲苯酚橙,PAN、TAR,PAR-H_2O_2,铜-铬天青S,ECR-CTMAB,3,5-diBr-PADAP,5-Br-PADAP-H_2O_2及DPC等方法,DPC法应用最广泛,但灵敏度不高,且需将Cr~(3+)氧化成Cr~(6+),当有还原性物质如S~2、Fe~(2-)、SO_3~2等存在时,会使结果偏低。特别是氯离子浓度高时,重现性不佳,结果偏低。为此我们曾提出Cr~(3+)-5-Br-PADAP-H_2O_2体系测定微量铬的方法。本文研究了在pH_4的乙酸盐-Ca-CyDTA-硫
Chromium photometry with xylenol orange, PAN, TAR, PAR-H_2O_2, copper-chrome azure S, ECR-CTMAB, 3,5-diBr-PADAP, 5-Br-PADAP-H_2O_2 and DPC and other methods, DPC The method is the most widely used, but its sensitivity is not high. It is necessary to oxidize Cr 3+ to Cr 6+. When there are reductive substances such as S 2, Fe 2 -, SO 3 2- When, will result in low. Especially when the chloride ion concentration is high, the reproducibility is poor and the result is low. To this end, we have proposed Cr ~ (3 +) - 5-Br-PADAP-H_2O_2 system for the determination of trace chromium. In this paper, acetate-Ca-CyDTA-Sulfur at pH 4 was studied