Design of an optical sensor for the determination of cysteine based on the spectrophotometric method in a triacetylcellulose film: PC-ANN application

Abstract

An optical sensor was developed for measuring the concentration of L-cysteine (Cys) based on the immobilization of an ARS–Cu complex to a transparent triacetylcellulose film. The spectrophotometric studies of the sensing films clearly indicate that the absorption enhances at 438 nm and decreases at 535 nm in acetate buffer solution pH 5.0 as a result of the interaction of Cys with Cu²⁺ of the copper–ARS complex and the reduction of Cu²⁺ to Cu⁺ which cause the release of ARS. With the optode membrane described, Cys in a sample solution can be determined with the linear range of 47.8 to 637.0 μM which was improved to 18.9–672.0 μM by applying the PC-ANN algorithm. The proposed optode obtained a limit of detection equal to 7.32 μM and its response time was about 16 min, depending on the concentration of Cys. The measurements of Cys in a real sample via the new optical sensor have shown an excellent correlation with values obtained for the same samples using HPLC as a standard method.