Saraiva Marina, Chekri Rachida, Leufroy Axelle, Guérin Thierry, Sloth Jens J, Jitaru Petru
Université Paris-Est, ANSES, Laboratory for Food Safety, F-94700, Maisons-Alfort, France; National Food Institute, Technical University of Denmark, Kemitorvet, Dk-2800, KGS Lyngby, Denmark.
Université Paris-Est, ANSES, Laboratory for Food Safety, F-94700, Maisons-Alfort, France.
Talanta. 2021 Jan 15;222:121538. doi: 10.1016/j.talanta.2020.121538. Epub 2020 Aug 15.
This study presents the development, validation and application of a new analytical approach for the simultaneous speciation analysis of Cr(III) and Cr(VI) in meat and dairy products by high-performance liquid chromatography (HPLC) coupled to inductively coupled plasma mass spectrometry (ICP-MS) and double spike species specific-isotope dilution (SS-ID). The species extraction was achieved by sequential complexation of Cr(III) with ethylenediaminetetraacetic acid (EDTA) and of Cr(VI) with 1,5-diphenylcarbazide (DPC) in the same analytical run. The HPLC separation of complexed species was carried out using a short (5 cm) microbore anion-exchange HPLC column and a mobile phase consisting of 0.01 mol L HNO + 2.5% (v/v) MeOH + 0.30 mol L EDTA (pH = 2) in isocratic elution mode with excellent baseline separation achieved in less than 3 min. The method was validated by means of the accuracy profile approach by carrying out 6 measurement series in duplicate on (six) different days over a timespan of two months. The quantification limit was 0.013 μg kg for Cr(III) and 0.049 μg kg for Cr(VI), respectively. The measurement bias corresponding to the validity domain ranged from 0.01 to 0.11%, whereas the coefficient of variation in terms of repeatability (CV) varied from 2.9 to 11.6% (depending on the analyte level) for Cr(III) and from 6.7 to 11.8% for Cr(VI). Similarly, the coefficient of variation in terms of intermediate reproducibility (CV) ranged from 6.8 to 13% for Cr(III) and from 6.8 to 25.9% for Cr(VI), respectively. The method was successfully applied to the analysis of a selection of food samples such as baby and semi-skimmed milk and steak beef samples. Cr(VI) was not quantified in any of these samples while Cr(III) levels ranged between 2.7 and 4.7 μg kg, which were comparable with the levels of total chromium analysed in the same samples by ICP-MS (accredited method). The method presented here with combined use of species specific isotope dilution and sequential species complexation is a powerful analytical tool for accurate and precise quantification of Cr(III) and Cr(VI) at trace levels and allows for correction of any species interconversion during sample preparation.
本研究介绍了一种新的分析方法的开发、验证及应用，该方法采用高效液相色谱（HPLC）与电感耦合等离子体质谱（ICP-MS）联用以及双标样物种特异性同位素稀释（SS-ID）技术，用于同时测定肉类和乳制品中Cr(III)和Cr(VI)的形态。在同一次分析运行中，通过Cr(III)与乙二胺四乙酸（EDTA）以及Cr(VI)与1,5-二苯卡巴肼（DPC）的顺序络合实现物种萃取。使用短（5 cm）微径阴离子交换HPLC柱和由0.01 mol/L HNO₃ + 2.5%（v/v）甲醇 + 0.30 mol/L EDTA（pH = 2）组成的流动相，在等度洗脱模式下进行络合物种的HPLC分离，不到3分钟即可实现出色的基线分离。通过在两个月的时间跨度内，在（六个）不同日期重复进行6次测量系列，采用准确度轮廓法对该方法进行了验证。Cr(III)的定量限为0.013 μg/kg，Cr(VI)的定量限为0.049 μg/kg。对应有效域的测量偏差范围为0.01%至0.11%，而Cr(III)的重复性变异系数（CV）在2.9%至11.6%之间（取决于分析物水平），Cr(VI)的重复性变异系数在6.7%至11.8%之间。同样，Cr(III)的中间再现性变异系数（CV）范围为6.8%至13%，Cr(VI)的中间再现性变异系数范围为6.8%至25.9%。该方法已成功应用于一系列食品样品的分析，如婴儿奶粉、半脱脂牛奶和牛排牛肉样品。在这些样品中均未检测到Cr(VI)的定量，而Cr(III)的含量在2.7至4.7 μg/kg之间，这与通过ICP-MS（认可方法）分析的同一样品中的总铬含量相当。本文介绍的结合使用物种特异性同位素稀释和顺序物种络合的方法是一种强大的分析工具，可用于准确、精确地定量痕量水平的Cr(III)和Cr(VI)并校正样品制备过程中任何物种的相互转化。
