双波长分光光度法测定溴化十六烷基三甲基铵

Determination of cationic surfactants with xylenol orange in water by dual-wavelength spectrophotometry

以二甲酚橙为显色剂,采用双波长分光光度法测定水中溴化十六烷基三甲基铵。实验确定的测定条件为：最大吸收波长为590 nm,等吸光度点的波长点为509 nm,选择pH为6.86的Na3PO4-Na2HPO4缓冲溶液3.50 mL,0.80 g/L二甲酚橙显色剂2.0 mL,显色时间为5 min。试剂加入顺序对测定结果基本无影响。CTMAB的质量浓度在0～1.2 mg/mL范围内符合比尔定律,标准曲线为ΔA=0.0123ρ＋0.0825,相关系数为R2=0.9998,样品加标回收率为99.6%～101.3%。

A method for the determination of cetyhrimethylarnmonium bromide （CTMAB） by dual-wavelength spectrophotometry with xylenol orange as a coloring reagent was proposed. The optimal conditions were as following- the maximum absorbance wavelength was 590 nm, the isosbestic point was at 509 nm, 3.5 mL of phosphate buffer solution （pH 6.86） and 2.0 mL of 0.80 g/L xylenol orange were used, and the coloring time was 5 min. The order of reagents added has no effect on the results. Beer＇s law was obeyed for CTMAB in the range of 0- 1.2 mg/mL, and the linear regression equation was △A = 0.0123ρ ＋ 0.0825 with the correlation coefficient of 0.9998. The recoveries were 99.6% - 101.3%.