SPECTROPHOTOMETRIC DETERMINATION OF CETYLTRIMETHYL-AMMONIUMBROMIDE WITH 4,4′-BIAZOBENZENEDIAZOAMINOAZOBENZENE

A novel spectrophotometric method for the determination of cetyltrimethyl ammoniumbromide (CTMAB) with 4,4′ biazobenzenediazoaminoazobenzene is developed. In the medium of 0.04~0.06 mol·L -1 sodium hydroxide, CTMAB reacts with 4,4′ biazobenzenediazoaminoazobenzene to form a purple 1∶1 complex of ion association in the presence of Triton X 100. Absorption maximum of the color complex is located at 575 nm with an apparent molar absorptivity of 5.02×10 4L·mol -1 ·cm -1 . Beer′s law is obeyed in the CTMAB concentration range of 0~100 μg per 25 mL of solution. The proposed method discribed above is simple and rapid without use of toxic organic solvent. It has been applied to the determination of trace CTMAB in tap water with satisfactory results.