Preconcentration of trace silver ion using modified silica and determination by flow injection flame atomic absorption spectrometry

Abstract

Silica gel chemically modified with benzothiazole calix[4]arene derivative (CU1-CHO) was synthesized via Schiff’s base (APS-CU1). The APS-CU1 was characterized by DR-UV and FT-IR spectroscopy and thermal gravimetric analysis. The APS-CU1 was used as an effective sorbent for solid phase extraction (SPE) of Ag(I). The sorption properties of Ag(I) were studied in batch and column methods. The optimum pH was found to be 6-7 with the contact time of 10 min. A maximum capacity of the sorbent under the optimum conditions was 12.2 mg of Ag(I) per gram of sorbent. The on-line flow injection pre-concentration coupled with FAAS (FI-FAAS system) base on SPE for determination of Ag(I) was investigation. The solution of Ag(I) was passed directly through sorbent at flow rate of 3.0 mL min⁻¹ and then eluted by 250 µL of 0.1 mol L⁻¹ thiosulfate at the flow rate of 1.5 mL min⁻¹. The analytical characteristics performance of FI-FAAS system were studied under optimum conditions using spiked solution with standard Ag(I) at 20 and 50 µg L- The detection limit of 8.8 µg L⁻¹ was obtained. The accuracy of the proposed method was evaluated and percentage of recovery were 100.2% and 99.5%, respectively. The percent relative standard deviations (%RSD) at 20 and 50 µg L⁻¹ were 6.1% and 3.3%, respectively. The developed method was successfully applied to the determination of trace Ag(I) in real water samples such as drinking water and tap water.