Ferreira Hadla S, Santos Ana C N, Portugal Lindomar A, Costa Antonio C S, Miró Manuel, Ferreira Sérgio L C
Universidade Federal da Bahia, Instituto de Química, Campus Universitário de Ondina, Salvador, Bahia 40170-290, Brazil.
Talanta. 2008 Oct 19;77(1):73-6. doi: 10.1016/j.talanta.2008.05.056. Epub 2008 Jun 11.
In this paper is proposed a simultaneous pre-concentration procedure using cloud point extraction for the determination of copper and zinc in food samples employing sequential multi-element flame atomic absorption spectrometry (FS-FAAS). The reagent used is 1-(2-pyridylazo)-2-naphthol (PAN) and the micellar phase is obtained using the non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114) and centrifugation. The optimization step was performed using Box-Behnken design for three factors: solution pH, reagent concentration and buffer concentration. A multiple response function was established in order to get an experimental condition for simultaneous extraction of copper and zinc. Under the optimized experimental conditions, the method allows the determination of copper with a limit of detection (3sigma(b)/S, LOD) of 0.1 microg L(-1), precision expressed as relative standard deviation (R.S.D.) of 2.1 and 1.3% (N=10), for copper concentrations of 10 and 50 microg L(-1), respectively. Zinc is determined with a LOD of 0.15 microg L(-1) and precision as R.S.D. of 2.7 and 1.7% for concentrations of 10 and 50 microg L(-1), respectively. The enhancement factors obtained were 36 and 32 for copper and zinc, respectively. The accuracy was assessed by analysis of certified reference materials, namely, SRM 1567a - Wheat Flour and SRM 8433 - Corn Bran from National Institute of Standards & Technology and BCR 189-wholemeal flour from Institute of Reference Materials and Measurements. The method was applied to the determination of copper and zinc in oats, powdered chocolate, corn flour and wheat flour samples. The copper content in the samples analyzed varied from 1.14 to 3.28 microg g(-1) and zinc from 8.7 to 22.9 microg g(-1).
本文提出了一种采用浊点萃取的同时预富集方法，用于食品样品中铜和锌的测定，采用顺序多元素火焰原子吸收光谱法（FS-FAAS）。使用的试剂是1-(2-吡啶偶氮)-2-萘酚（PAN），胶束相通过非离子表面活性剂辛基苯氧基聚乙氧基乙醇（Triton X-114）和离心获得。优化步骤采用Box-Behnken设计，涉及三个因素：溶液pH值、试剂浓度和缓冲液浓度。建立了一个多响应函数，以获得同时萃取铜和锌的实验条件。在优化的实验条件下，该方法测定铜的检测限（3σ(b)/S，LOD）为0.1 μg L(-1)，当铜浓度分别为10和50 μg L(-1)时，精密度以相对标准偏差（R.S.D.）表示，分别为2.1%和1.3%（N = 10）。测定锌的LOD为0.15 μg L(-1)；当锌浓度分别为10和50 μg L(-1)时，精密度以R.S.D.表示，分别为2.7%和1.7%。获得的铜和锌的富集因子分别为36和32。通过分析美国国家标准与技术研究院的标准参考物质SRM 1567a - 小麦粉和SRM 8433 - 玉米麸皮以及参考物质与测量研究所的BCR 189 - 全麦粉来评估准确度。该方法应用于燕麦、巧克力粉、玉米粉和小麦粉样品中铜和锌的测定。分析的样品中铜含量在1.14至3.28 μg g(-1)之间，锌含量在8.7至22.9 μg g(-1)之间。
