Direct determination of polyacrylamide in water samples by its enhancement effect on the resonance Rayleigh scattering of some basic diphenyl naphthylmethane dyes

Abstract

Interaction of partially hydrolyzed polyacrylamide (HPAM) with basic diphenyl naphthylmethane dyes including victoria blue 4R (VB4R), victoria blue B (VBB) and night blue (NB), was characterized by resonance Rayleigh scattering (RRS) spectra. Accordingly a RRS method for the direct determination of HPAM at nanogram levels has been developed. The maximum RRS wavelengths (λmax) appear at 276 nm, 284 nm, and 374 nm for VB4R, VBB, and NB systems, respectively. The RRS spectral characteristics, the influencing factors, and the optimum conditions have been investigated. The RRS intensity was directly proportional to the concentration of HPAM in the range of 0.054∼3.5 µg mL−1 for VB4R system, 0.10∼5.0 µg mL−1for VBB system, and 0.10∼1.5 µg mL−1 for NB system. The methods exhibited high sensitivities. The detection limits were 16.5 ng mL−1 (VB4R system), and 31.0 ng mL−1 (VBB and NB systems). The selectivity of the method was investigated by using VB4R system owing to the highest sensitivity. Concentrations of HPAM in tap water, synthetic water and practical waste water samples were analyzed satisfactorily. The reaction mechanism and RRS enhancement reasons were discussed.