title: Determination of trace copper in food samples by flame atomic absorption spectrometry after solid phase extraction on modified soybean hull.
abstract: Soybean hull was chemically modified with citric acid and used as a solid phase extraction adsorbent for the determination of trace amounts of Cu(2+) in food samples by flame absorption spectrometry (FAAS). The effect of pH, sample flow rate and volume, elution flow rate and volume and co-existing ions on the recovery of the analyte were investigated. The results showed that Cu(2+) could be adsorbed on the modified soybean hull at pH 8.0 and eluted by 2.0 mL of 1.0 mol L(-1) HCl. Under the optimized conditions, the adsorption capacity of modified soybean hull was found to be 18.0 mg g(-1) for Cu(2+). The detection limit of the proposed method was 0.8 ng mL(-1) for Cu(2+) with an enrichment factor of 18. The analytical result for the certified reference tea sample (GBW07605) was in a good agreement with the certified value. The proposed method has also been successfully applied to the determination of trace Cu(2+) in dried sweet potato, lake water and milk powder, the recovery of Cu(2+) for spiked samples was between 91% and 109.6%.
authors.affiliation: School of Chemistry and Chemical Engineering, Henan University of Technology, Zhengzhou 450001, PR China. xianggq@126.com
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Xiang
authors.forename: Yingming
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xiuming
authors.initials: X
authors.lastname: Jiang
authors.forename: Lijun
authors.initials: L
authors.lastname: He
authors.forename: Lu
authors.initials: L
authors.lastname: Fan
authors.forename: Wenjie
authors.initials: W
authors.lastname: Zhao
mesh_terms: D000327:Adsorption; D003300:Copper / Q000032:analysis*; D003611:Dairy Products / Q000032:analysis; D005504:Food Analysis / Q000379:methods*; D005618:Fresh Water / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D027723:Ipomoea batatas / Q000737:chemistry; D012015:Reference Standards; D052616:Solid Phase Extraction; D012995:Solubility; D013025:Glycine max / Q000737:chemistry*; D013054:Spectrophotometry, Atomic; D013662:Tea / Q000737:chemistry
chemical_list: D007202:Indicators and Reagents; D013662:Tea; D003300:Copper