A selective and sensitive chemical optical sensor was prepared based on citrate capped gold nanoparticles growth in polyvinyl-alcohol (PVA) holding matrix and congo red (CR)-functionalized (PVA-Au-Citrate-NPs-CR), while consequently applied for the determination of trace amount of Cr(III) ion in aqueous media. Polyvinyl alcohol and trisodium citrate as a processor of Gold nanoparticles have the safest NFPA 704 so there is not any toxicity for using them in any condition including biological samples. The PVA-Au-Citrate-NPs-CR sensor was characterized via UV-Vis, SEM, DLS, XRD, MR, and EDS. At best operational conditions, an understudy sensor applied for monitoring the Cr(III) ion over 8.06 x 10(-6)-5.26 x 10(-5) mol L-1 with a detection limit of 2.418 x 10(-6) mol L-1. The present sensor has an acceptable response time as fast as 60 s with high stability over 1 month. The PVA-Au-Citrate-NPs-CR sensor is highly selective for Cr(III) ion in the presence of Cu2+, Pb2+, Co2+, Ag+, etc with good repeatability and reproducibility and satisfactory relative standard deviation (R.S.D) (less than 4.044% and 3.535%, respectively). Finally, the developed PVA-Au-Citrate-NPs-CR sensor is used for Cr(III) ion in different real water and green tee samples and in all situations, their accuracy was checked using recovery and RSD. (C) 2019 Published by Elsevier Ltd.
