海藻中铬形态和含量的检测分析方法研究

为研究海藻中铬的形态和含量,本试验采用IonPac CG5A(4 mm×50 mm)阳离子色谱柱,考察并优化络合剂的种类和浓度、流动相的种类和浓度、pH值、温度及游离态铬的提取方式等条件对Cr(Ⅲ)和Cr(Ⅵ)分离效果的影响。采用高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)对Cr(Ⅲ)和Cr(Ⅵ)进行分析,并利用电感耦合等离子体质谱(ICP-MS)测定海藻中总铬、结合态铬、游离态铬的含量。结果表明,海藻样品在40℃超声条件下,以5 mmol·L^-1吡啶-2,6-二羧酸(PDCA)的硝酸铵溶液(pH值7.0)为络合剂提取10 min,以50 mmol·L^-1硝酸铵溶液作为流动相,可同时测定海藻中Cr(Ⅲ)和Cr(Ⅵ),该方法操作简单,灵敏度和准确度高。此外,海藻中的铬主要以结合态形式存在,游离态铬的含量较低,且游离态铬以Cr(Ⅲ)形态存在为主。Cr(Ⅵ)形态较少,且含量均低于检出限。本试验通过建立海藻中Cr(Ⅲ)和Cr(Ⅵ)分析方法并对海藻中各种形态铬的含量进行分析检测,为相关标准的制定提供了分析方法和数据支撑。

Detection and Speciation Analysis of Chromium in Seaweeds

To study the speciation and content of chromium in seaweeds, we investigated and optimized the conditions of complexing agent type and concentration, mobile phase type and concentration, pH, temperature and extraction method of total soluble Cr for the separation of Cr(Ⅲ) and Cr(Ⅵ) using IonPac CG5A (4 mm×50 mm) cation-exchange column, Cr(Ⅲ) and Cr(Ⅵ) were further analyzed by High Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry (HPLC-ICP-MS). The total Cr and total bound Cr and total soluble Cr in seaweeds were measured by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The results showed that the optimized conditions for simultaneous detection of Cr (Ⅲ) and Cr (Ⅵ) in seaweeds could be achieved by ultrasonic extraction of seaweeds at 40℃ for 10 min with 5 mmol·L^-12,6-Pyrinedicarboxylic acid (PDCA) ammonium nitrate solution (pH=7.0) as complexing agent, and separated by 50 mmol·L^-1 ammonium nitrate solution was used as the mobile phase. It was a simple method with high sensitivity and accuracy. In addition, the bound Cr was the majority speciation of chromium in seaweeds, comparing to the soluble Cr in lower content which was occupied by Cr (Ⅲ). In this experiment, the methods for simultaneous analysis of Cr (Ⅲ) and Cr (Ⅵ) with parallel Cr species analysis in seaweeds were established, and the content of Cr in various speciation were detected. These results would provide detection method and data support for the formulation of relevant standards.