微波灰化-液相色谱-电感耦合等离子体质谱联用测定干食用菌中的三价铬和六价铬

建立了干食用菌中三价铬(Cr(Ⅲ))和六价铬(Cr(Ⅵ))的液相色谱-电感耦合等离子体质谱(LC-ICP-MS)检测方法。采用微波灰化技术对食用菌样品进行灰化处理，灰化样品用乙二胺四乙酸(EDTA)二钠盐稳定其中的Cr(Ⅲ)，并使其保留在阴离子交换柱(250 mm×4.6 mm，10 μm)上；用含有60 mmol/L硝酸(pH 9.3)的流动相分离其中的Cr(Ⅲ)和Cr(Ⅵ)，电感耦合等离子体质谱仪测定。标准溶液中Cr(Ⅲ)和Cr(Ⅵ)的质量浓度在0.5~50 μg/L范围内呈良好的线性关系，线性回归系数均达到0.9999。食用菌样品中Cr(Ⅲ)和Cr(Ⅵ)不同加入量的平均回收率为78.0%~90.7%，相对标准偏差小于4%(n=6)；定量限均为0.5 μg/L。该方法稳定、可靠、灵敏，可满足干食用菌中Cr(Ⅲ)和Cr(Ⅵ)的测定。

Determination of trivalent chromium and hexavalent chromium in dried edible fungi by microwave ashing-liquid chromatography with inductively coupled plasma mass spectrometry

An analytical method using liquid chromatography with inductively coupled plasma mass spectrometry (LC-ICP-MS) for the determination of trivalent chromium (Cr(Ⅲ)) and hexavalent chromium (Cr(Ⅵ)) in dried edible fungi was established. Edible fungi sample was ashed by a microwave ashing system and Na₂EDTA was added to the ashing sample to stabilize the Cr(Ⅲ). An anion exchange column (250 mm×4.6 mm, 10 μm) with a 60 mmol/L nitric acid (pH 9.3) solution as mobile phase was used for the separation and using ICP-MS as a detector for the determination of trivalent chromium and hexavalent chromium. The calibration curves were linear in the range of 0.5-50 μg/L and the correlation coefficients were 0.9999 for Cr(Ⅲ) and Cr(Ⅵ). The average recoveries of Cr(Ⅲ) and Cr(Ⅵ) ranged from 78.0% to 90.7% with the relative standard deviations (RSDs, n=6) less than 4%. The limits of quantification (LOQ) of Cr(Ⅲ) and Cr(Ⅵ) were 0.5 μg/L. The method is efficient, reliable and sensitive, and can meet the requirement for the determination of Cr(Ⅲ) and Cr(Ⅵ) in dried edible fungi.