A new spectrophotometric method for detection of cetyhrimethylammonium bromide ( CTAB) based upon formation of the Al(Ⅲ) - Chromeazurol S (CAS) -CTAB ternary complex system was studied. Results showed that in the medium of pH = 6. 0 Britton - Robinson buffer solutions, the color reaction of Al ( Ⅲ ) with CAS could be enhanced by adding CTAB. The maximum absorption wavelength of the ternary complex Al( Ⅲ) -CAS - CTAB was at 640 nm. When the amount of 5. 0 × 10-4 mol · L-1 CAS and 20 μg · L-1 Al( Ⅲ) was 1. 00 mL and 1. 00 mL respectively, mass concentration of CTAB in the range of 5 -100 mg · L-1 shows good linearity vs. the absorbance of the system. This developed method can be used for the determination of CTAB in waste water samples with satisfactory results. The spiked recovery rate is in the range of 97% -103%.%采用分光光度法对十六烷基三甲基溴化铵(CTAB) - Al(Ⅲ)-铬天青S(CAS)三元络合物体系进行了研究.研究发现,在pH =6.0的B-R缓冲液中,CTAB的加入导致Al(Ⅲ)- CAS二元络合体系的吸光度增加,并在640 nm波长处产生最大吸收.实验结果表明,当5.0×10-4 mol· L-1的CAS溶液用量为1.00 mL,20 μg·L-1的Al(Ⅲ)溶液用量为1.00 mL时,CTAB质量浓度(P)在5～100 mg·L-1范围内与体系吸光度(A)呈良好的线性关系,线性方程为A =0.22341p -0.04237,相关系数r=0.9999.该法用于环境水样中CTAB的测定,加标回收率为97％～103％.
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