Solid Phase Extraction and Determination of Lead in Water Samples Using Silica Gel Homogeneously Modified by Thiosalicylic Acid

Abstract

Silica gel was modified by thiosalicylic acid via homogeneous routes to obtain immobilized silica gel sorbent (TSA‐immobilized silica gel). This new sorbent was characterized using variety of physical chemistry techniques including, high resolution solid state ¹³C and ²⁹Si CP/MAS NMR, X‐ray photoelectron spectroscopy (XPS), thermal analysis (TGA and DTA), elemental analysis, and BET surface analysis as well as infrared spectroscopy (FTIR). New support was used for the selective extraction and concentration of lead ions by silica gel modified with thiosalicylic acid, as a highly selective and stable reagent, from aquatic samples and its determination with FAAS. Lead ions can be desorbed with 4 mol dm^?3 HNO₃. The sorption capacity for lead ions are found in the range of 64.40 to 69.90 µmol g^?1 of chelating matrix. Tolerance limits for electrolytes and some trace metals in the sorption of lead is reported. Preconcentration factor was found as 150 for Pb(II). The lead in drinking water, mineral water, tap water, and fruit juice was quantitatively recovered with a relative standard deviation lower than 1.50%. A detection limit of the method for lead ions was found as 3.7 µg l^?1.