Solid phase extraction and sequential elution for pre-concentration of traces of Mn and Zn in analysis of honey by flame atomic absorption spectrometry

摘要

A pre-concentration procedure based on solid phase extraction and two-step elution was developed for the determination of the total concentrations of traces of food safety relevant elements (Mn and Zn) in ripened honeys. Accordingly, 10% (m/v) solutions of analyzed honeys (100 ml) were passed at 20 ml min?1 through resin beds of Dowex 50W × 8–400 to retain Mn and Zn ions and separate them from the glucose and fructose matrix. Afterwards, 20 ml of a 0.5 mol l?1HNO3 solution was used to elute K and Na, easily ionized interfering metals. Finally, Mn and Zn were recovered prior to measurements by flame atomic absorption spectrometry (FAAS) using 5 ml of a 2 mol l?1HCl solution. This procedure was applied in the analysis of six honeys and resulted in the determination of 0.2–13.6 μg g?1 of Mn and 0.2–1.2 μg g?1 of Zn with the precision (n = 3) within 3–10% and an accuracy better than 5%. Detection limits of Mn and Zn with this pre-concentration/separation procedure and the FAAS detection were 4 and 3 ng g?1, respectively...