Determination of Trace Ga in Water and Plant Samples by O2-doped Air-Acetylene FAAS with Solid Phase Extraction Preconcentration

Abstract

BACKGROUND At present, research on the extraction separation and enrichment of gallium is mostly biased to the strong acidic system, which brings a safety risk to the operation and needs acid-proof apparatus. Furthermore, the procedure is easily contaminated, resulting in high background values. OBJECTIVES To develop a method for extraction separation and preconcentration of trace Ga under weakly acidic condition. METHODS Solid phase extraction medium for Ga was prepared by using modified large porous adsorption resin with cetyl-trimethyl-ammonium bromide and loading it with 2-ethylhexyl phosphonic acid-2-ethylhexyleste. The separation and enrichment conditions of solid phase extraction were studied in detail. RESULTS Experiments showed that the separation and enrichment of trace gallium was ideal when the extraction conditions were mild. The maximum recovery (99%) of Ga was achieved in sample solution with pH of 2.5. The determination parameters of gallium were optimized for oxygen doped air-acetylene flame atomic absorption spectrometry (FAAS), and the sensitivity was improved on that of the current method. The detection limit of the overall method (3σ) was 2.6ng/mL by IUPAC definition and the relative standard deviation (RSD, n=7) was 2.87%. The recoveries for spiked solution ranged from 95.7% to 102.0%, and a theory enrichment factor of 40 was obtained. CONCLUSIONS This method has been successfully applied to the determination of trace gallium in tap water, Chinese medicine and hydroponic vegetable samples. It is simple, quick and reliable.

Keywords

• water
• plant
• ga
• solid phase extraction
• oxygen doped air acetylene flame
• atomic absorption spectrometry