Influence of surfactants on the determination of trace aluminum by chrome azurol S spectrophotometry

The influence of surfactants such as CTMAB,CPB,PVA,SLS and CTMAB-SLS on the determination of trace aluminum by Al-CAS spectrophotometry was researched in the aspects of absorption spectra,composition of the complex,acidity,system stability and calibration curve.The results showed that the sensitivity of Al-CAS-CTMAB-SLS system was much higher than that of other five ones(Al-CAS,Al-CAS-CPB,Al-CAS-PVA,Al-CAS-SLS and Al-CAS-CTMAB).Al-CAS-CTMAB-SLS system has an maximum absorption peak at 642 nm,and the apparent molar absorptivity is 1.03×105 L·mol-1·cm-1.Beer′s law was obeyed in the range of 0 to 10 μg for Al3+ in 25 mL solution.The regressive equation was calculated as A=0.100 ρ+0.025 3,with a correlation coefficient of 0.999 0.This method has been applied to the determination of trace aluminum in water samples with the RSD of less then 2% and the recovery of 98%-102%.