Spectrophotometric Determination of Cationic Surfactants Based on Their Effect on the Complexes of Chrome Azurol S with Be2+ and Al3+ Cations

Abstract Simple, rapid, and sensitive spectrophotometric methods have been proposed for the determination of cationic surfactants (CS) as cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium (DTAB), and cetylpyridinium bromide (CPB). The methods are based on the effects of CSs on the complexes of Al 3+ and Be 2+ with Chrome Azurol S (CAS). The optimum reaction conditions such as CAS concentration, metal ion concentration, and pH have been studied and found to be 2.0 × 10 −4 mol L −1 CAS, 0.5 mg L −1 Al 3+ or 0.4 mg L −1 Be 2+ and pH 5.4. The analytical characteristics of the methods such as limit of detections, limit of quantifications, and linear ranges have been obtained. CTAB, CPB, and DTAB could be determined by the Al–CAS complex in the ranges of 0.50–40.00, 0.20–10.00, and 0.40–10.00 µmol L −1 , and for the Be–CAS complex in the ranges of 0.08–5.00, 0.08–3.00, and 0.20–6.00 µmol L −1 , respectively. The limit of the detections of the method for the determination of CTAB, CPB, and DTAB for the Be–CAS complex has been found as 0.025, 0.024, and 0.061 µmol L −1 , respectively. The interfering effect of some anions and cations was also tested. The method was applied to the determination of CS CTAB in conditioner shampoo and water samples.