Novel Enzymatic Potentiometric Approaches for Surfactant Analysis

The present study described a novel application of simple potentiometric enzymatic method for analysis of surfactants based on their inhibitory effect on acetylcholinesterase enzyme (AChE). The enzymatic activity was measured through monitoring hydrolysis of acetylcholine (ACh) with a disposable acetylcholine potentiometric sensor. Comprehensive investigations were carried out including the effect of incubation time, cholinesterase enzyme and the working calibration ranges. Based on inhibition of AChE, different cationic, anionic and nonionic surfactants were determined in the concentration range from 0 to 40 μg mL−1 with detection limits reaching 0.07 μg mL−1 depending on the nature of surfactants. The degree of AChE inhibition caused by different tested surfactants were as follows: cetylpyridinium chloride (CPC)>benzyldimethylhexadecyl ammonium chloride (BDHAC)>Hyamine (Hy)>cetyltrimethylammonium bromide (CTAB)>Triton X‐100 (TX‐100)>sodium dodecyl sulphate (SDS). The proposed method was applied for determination of surfactants in pharmaceutical formulation, detergents products and environmental samples with acceptable sensitivity and reproducibility.