Determination of Trace Amounts of Tin by Reversed-phase HPLC after Solid Phase Extraction-Preconcentration with XAD Resin Coated with N-Benzoyl-N-phenylhydroxylamine

Abstract

A solid phase extraction method for concentration of tin, and a new determination method for tin by reversed-phase high performance liquid chromatography (RP-HPLC) were described.
Amberlite XAD-7 resin coated with N-benzoyl-N-phenylhydroxylamine (BPHA) was prepared, and applied to the preconcentration of trace tin from aqueous solution. Tin was quantitatively adsorbed on the resin coated with reagent (BPHA/XAD resin) from 0.25 mol dm⁻³ hydrochloric acid solution by the batch method. After collection, tin adsorbed on the BPHA/XAD resin as tin-BPHA chelate was eluted easily by shaking with 0.5 mol dm⁻³ sulfuric acid-ethanol (1 : 1, v/v) mixture. This collection and elution method was applied to the RP-HPLC determination of trace tin. 2-(5-Nitro-2-pyridylazo)-5-[N-propyl-N-(3-sulfopropyl)amino] phenol (Nitro-PAPS) was used as a precolumn chelating agent for the reversed-phase liquid chromatographic determination of tin. Tin(IV) chelate was eluted on an ODS column with ethanol-water (60 : 40) mixture containing 1.0 mol dm⁻³ acetic acid, 0.01 mol dm⁻³ TBA⁺Br⁻ and 10⁻⁶ mol dm⁻³ EDTA as mobile phase, and then determinated with a UV-VIS detector. The calibration curve was linear over 0–8.0 ng cm⁻³ at 0.002 absorbance unit full scale and at 580 nm. The relative standard deviation for 4.0 ng cm⁻³ at three determinations was estimated to be 1.8%. The detection limit for tin was 0.58 ng cm⁻³ (3σ). Moreover, tin could be measured sensitively and selectively by combining BPHA/XAD resin solid phase extraction with HPLC method. After concentration of tin from 500 cm³ sample solution with the BPHA/XAD resin solid extraction method, the detection limit of the proposed method was 0.03 ng cm⁻³ (3σ). The proposed method was applied to the determination of trace amounts of tin in water samples.