Comparative Study of Silver Nanoparticles (AgNPs) Synthesized from Purified and Unpurified Ocimum sanctum Leaves Extract and Their Application as a Colorimetric Sensor for Hg2+ Detection
Yussi Pratiwi, Fuad Alfan Asyifa, Agus Darmawan, Harfi Amania Khansa, Listya Eka Anggraini, Aneesha Sheik Musthafa Ajeetha

Department of Chemistry, Faculty Mathematics and Sciences, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia
Department of Chemistry, Faculty Mathematics and Sciences, Universitas Negeri Jakarta, Jakarta 13220, Indonesia
Department of Chemistry, King Fahd University of Petroleum and Minerals (KFUPM), Dhahran 31261, Saudi Arabia
Department of Chemistry, Karpagam Academy of Higher Education, Coimbature 641021, India

Abstract

The presence of Hg(II) ions can accumulate in soil and water can harm living organisms, including humans. An alternative method called silver nanoparticles (AgNPs) as a colorimetric sensor can be used to detect the presence of Hg(II) directly on site. Green synthesis of AgNPs using plant extracts has been widely carried out, but research regarding the use of purified and unrefined plant extracts has not been widely carried out. This study presents a comparative evaluation of AgNPs synthesized from purified and unpurified Ocimum sanctum (tulsi) leaf extract, characterize the resulting AgNPs, and evaluate the analytical performance of the sensor modified as nanocomposite. Comparative result revealed that AgNPs synthesized from unpurified extract exhibited smaller size, homogenous, and more colloidal stability, with a size of 66,8 nm, polydispersity index of 0,295, and zeta potential of -26,9 mV. AgNPs synthesized from unpurified extract were modified into nanocomposite film using chitosan-starch to obtain a sensor with high selectivity toward Hg(II) ions, sensitivity in the concentration range of 100 ppm to 50 ppb, and stability for up to four weeks. The nanocomposite film sensor had a LOD of 0.8 ppm and a LOQ of 2.4 ppm.

Keywords: colorimetric sensor, mercury, silver nanoparticles, tulsi leaf extract

Topic: Analytical Chemistry