串联双柱固相萃取-原子吸收光谱法检测葡萄酒中Fe、Cu和Mn的形态

Determination of Iron, Copper and Manganese in Wine by Tandem Solid Phase Extraction and Atomic Absorption Spectroscopy

摘要:

通过优化固相萃取（SPE）条件，分析pH值、有机酸对模拟葡萄酒中金属形态测定结果的影响，建立了一种快速准确、适用于葡萄酒中Fe、Cu、Mn形态分析的串联双柱固相萃取-原子吸收光谱法（AAS）联用技术。结果显示，在Polyclean X-HLB柱最佳活化条件和流速（1 mL/min）下，串联使用Superclean SCX柱（流速2 mL/min）可高效分离酒样中的目标物质，将金属形态分为疏水态、阳离子和残留态，之后直接进样石墨炉原子吸收光谱仪（GFAAS）测定金属含量；3种金属的方法检测限为0.39~1.56 μg/L，加标回收率为90.53%~112.18%，相对标准偏差为0.89%~7.12%；方法灵敏度、回收率高，重现性好。在葡萄酒pH值（3.00~4.00）条件下，pH变化和有机酸种类对Fe3+、Cu2+的形态分布具有显著影响，而对Mn2+的形态（主要是阳离子）的影响很小。在真实酒样中，白、红葡萄酒中Fe、Cu、Mn的形态分布不同，受葡萄酒成分和氧化还原状态的影响，以残留态（Fe、Mn）或疏水态（Cu）为主。

Abstract:

A rapid and accurate method for the speciation analysis of iron (Fe), copper (Cu) and manganese (Mn) in wine was developed using a tandem column solid phase extraction (SPE) and an atomic absorption spectrometry (AAS). The optimization of SPE conditions, and the effects of pH values (3.00~4.00) and organic acids (single or blend) on recovery rates of metal fraction were investigated in wine-like solutions. Under the optimized activation conditions and flow rate (1 mL/min) of Polyclean X-HLB column linking the column of Superclean SCX at a flow rate of 2 mL/min, these metals were efficiently fractionated into hydrophobic, cationic and residual forms, with a subsequent direct determination of metal ions by graphite furnace AAS. The limit of detection for Fe, Cu and Mn was from 0.39 to 1.56 μg/L, obtaining the recoveries from 90.53% to 112.18%, with the relative standard deviation between 0.89% and 7.12%, suggesting the assay is sensitive with good reproducibility. In aqueous alcoholic solutions, significant effects of pH and organic acids on the distribution of ferric and cupric ions were observed, while few effects were found for manganous (II) ion. In real wine samples, the distributions of Fe, Cu or Mn were different between white and red wines, and were affected by chemical components and the redox state of a wine, present with the predominant residual (Fe, Mn) or hydrophobic (Cu) form.