Simultaneous Determination of Heavy Metals Using Array Based Optical Chemical Sensor

A sol-gel optical chemical sensor encapsulated with complexing agents for simultaneous detection of selected heavy metals such as chromium and iron in aqueous media was fabricated. The sensor was prepared by acid catalyzed copolymerization of tetramethoxysilane(TMOS) and starch. 300μL of TMOS and starch mixture was load to the 96 well plate and then the gelation was completed within 2 hours. The composition of TMOS and starch, pH and detection range of heavy metals were optimized. 100μL of environmental and laboratory samples spiked with heavy metals were used to evaluate the application of the chemical sensor array to real samples. The chemical sensor exhibited high specificity in identifying multiple analytes. No obvious cross-interference was obtained when a 96 Well plate sensor array was used for simultaneous analysis of multiple samples in the presence of multiple analytes. The snesor array showed high reproducibility and relative standard deviation of 5%(n=10) was obtained. The developing reaction time was completed within at least 20 minutes. The detection limit of selected heavy metals was between 10 to 50μM by naked eye or Well plate reader. The physical properties have been investigated by various technique such as FTIR, XRD, SEM, TG-DTA to obtain information on chemical, structural and morphological composition of the layer.