Synthesis, characterization and use of Silica Gel Phases with chemically immobilized 2-Aminothiophenol for pre-concentration and determination of trace amounts of lead by Flame Atomic Absorption Spectrometry

Developing an appropriate, cost effective and at-hand method for determination of trace amounts of heavy metals in the water bodies is an on-demanding job due to the rate of present industrialization and the need for aquatic ecosystem health monitoring. An analytical method using silica gel chemically modified with 2-aminothiophenol for pre-concentration and subsequent determination of lead using flame atomic absorption spectrometry (FAAS) was developed. In order to determine optimum conditions of quantitative solid phase extraction of lead by 2-aminothiophenolpropyletrimetoxysilane (AmPTMS), parameters such as pH and flow rate were investigated. The aromatic group, 2-Aminothiophenol can be utilized in grafting reactions of silica gel surface, using 3-chloropropyletrimetoxysilane as a bridging molecule. Optimum conditions for pH and flow rate of recovery and pre-concentration of lead from its aqueous solution were 5.0 and 1.0 ml min-1, respectively. A 4.12 ng/ml detection limit for the pre-concentration of aqueous solution of lead was obtained. AmPTMS showed to be an efficient system for metal pre-concentration. The proposed method was simple, accurate and cost effective, especially when more sophisticated techniques such as GFAAS or ICP-OES are not available. The proposed procedure has been successfully applied for lead determination at μg levels in industrial and river water samples.