Determination of Picogram Amounts of Dihydroxybenzenes in Water Samples with Luminol–lysozyme Chemiluminescence System

An ultrasensitive method for the determination of dihydroxybenzens by flow injection (FI) chemiluminescence (CL) analysis was proposed for the first time. It was found that the CL intensity of luminol–lysozyme system could be significantly inhibited by dihydroxybenzens. The CL intensity decrements were linear with the logarithm of dihydroxybenzens concentrations over the ranges of 1.0 ～ 700 pg mL^‐1 for hydroquinone (HQ), 5.0 ～ 700 pg mL^‐1 for catechol (CT) and 10 ～ 7000 pg mL^‐1 for resorcinol (RS), with the corresponding limits of detection of 0.7, 3.0 and 7.0 pg mL^‐1, respectively. The proposed method was successfully applied to the determination of CT in tap water, rain water, river water and HQ in waste photographic developer samples, with recoveries from 93.5 to 105.8% and relative standard deviations (RSDs) less than 4.0% (n = 5). The possible interaction mechanism of lysozyme with dihydroxybenzens was discussed, and CT to lysozyme's binding constant and the thermodynamic parameters were given by the homemade FI–CL model. The results shown that the binding of dihydroxybenzens to lysozyme was spontaneous with the hydrophobic force.