Determination of trace chromium by catalytic kinetic spectrophotometry with alizarin red-cetyltrimethyl ammonium bromide system
SHEN Shu-jun1,ZOU Xiao-yong2
1. Department of Food and Biology Engineering,Zhangzhou Institude of Technology,Zhangzhou 363000,China; 2. School of Chemistry and Chemical Engineering,Sun Yat-Sen University,Guangzhou 510275,China
Abstract:In pH 5.0 HAc-NaAc buffer solution medium,with cetyl trimethyl ammonium bromide (CTMAB) as sensitizer and phenanthroline (phen) as activator,Cr had a significant catalytic effect on the oxidizing discoloration reaction between alizarin red (ARS) and hydrogen peroxide,so a novel method for the determination of trace Cr was established by kinetic spectrophotometry and the influence factors on the catalytic discoloration reaction were examined. Under the selected experimental conditions,the non-catalytic reaction system and the catalytic system had the same maximum absorption wavelength at 553 nm,and Cr in the concentration range of 0.001-0.10 μg/mL showed a good linear relationship. The regression equation was ΔA = 9.404ρ (μg/mL)-0.020 7 with correlation coefficient r = 0.998 1 and detection limit of 0.80 ng/mL. The method was applied to the determination of chromium in water and soil samples.The results were consistent with those obtained by atomic absorption spectrometry,and the relative standard deviation (RSD,n=6) was 1.7%-3.0%.
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