Alginate-AuNPs biofilm functionalized by thiourea for spectrophotometric sensing of palladium ions

Palladium is an infrequent and expensive metal. Although the palladium has many applications in electronics industry, medical (e.g., Blood glucose test strips) , dental, chemical industry and aircraft, it is a toxic metal. All palladium compounds are toxic and carcinogenic. Palladium causes irritation of skin, eye, respiratory tract and skin allergy. The solution of palladium causes skin burns and eye. Therefore, measurement of palladium in natural samples is very important. In this work,we have designed a novel method for the synthesis of alginate-AuNPs biofilm functionalized by thiourea, in order to measure trace amounts of palladium ions. The AuNPs were synthesized by slowly and dropwise adding proper amounts of borax solution in to the mixture of alginate-Aucl4- as the main matrix [1]. The characteristics of the synthesized of alginate-Aucl4- film was studied by TEM, particle size analyser and UV-Vis spectrophotometry [2]. The absorption spectra showed that the maximum wavelength of thiourea capped nanoparticles was 520 nm. The effect of various parameters on the measurement of palladium such as pH of the analyte solution, buffer volume and thiurea concentration was studied and optimized. Under the established optimum conditions,the calibration curve was linear in the range of 0.05-2.10 µg mL-1 (r=0.9953) with a detection limit of 0.038 µg mL-1. The relative standard deviation for ten replicate measurements of 1.2 µg mL-1of palladium was 4.4 %, respectively. The prepared biofilm showed good absorbance stability over time. Furethermore, the measurement process was fast, easy and without uses of toxic or harmful materials and solvent. The sensing system was sucessfully applied for the determination of palladium in various samples.