氢化物发生-电感耦合等离子体串联质谱法分析大米中的无机砷

Inorganic Arsenic Analysis in Rice by Hydride Generation Inductively Coupled Plasma-Tandem Mass Spectrometry

建立氢化物发生-电感耦合等离子体串联质谱(inductively coupled plasma-tandem mass spectrometry,ICPMS/MS)法直接测定大米中无机砷含量的高通量分析方法。采用硝酸-双氧水提取大米样品中的无机砷,以5 mol/L盐酸作为预还原剂将砷(V)还原为砷(III),在多模式样品导入系统中利用2 g/100 mL硼氢化钠溶液将无机砷(III)还原为挥发性胂(AsH_(3)),导入ICP-MS/MS直接进行测定;在MS/MS模式下,采用氧气为反应气,将砷转移为氧化砷消除质谱干扰,砷的检出限为0.004μg/L。方法用于分析标准参考物质大米粉(GBW(E)100348a、GBW(E)100349a、NIST SRM1568b)中无机砷,测定结果与参考物质的认定值基本一致,验证方法准确性好。方法无需与色谱技术联用进行砷的形态分离也能单独测定大米中的无机砷,具有操作简单快速、灵敏度高、准确可靠的特点,适用于大米中无机砷含量的测定。

A high throughput analytical method for the direct determination of inorganic arsenic content in rice by hydride generation(HG)inductively coupled plasma-tandem mass spectrometry(ICP-MS/MS)was established.Inorganic arsenic was extracted from rice samples with a mixture of nitric acid and hydrogen peroxide.Arsenic(V)was pre-reduced into arsenic(III)by adding 5 mol/L hydrochloric acid,and then 2 g/100 mL sodium borohydride solution was used to reduce inorganic arsenic(III)into volatile arsenic hydride(AsH_(3))in a multimode sample introduction system(MSIS).Finally,AsH_(3) was injected into the ICP-MS/MS system and directly detected.In the MS/MS mode,arsenic was transferred to arsenic oxide using oxygen as reaction gas to eliminate the mass spectral interference.The limit of detection(LOD)for arsenic was 0.004μg/L.The results of the method for inorganic arsenic in standard reference materials of rice flour(GBW(E)100348a,GBW(E)100349a,and NIST SRM1568b)were consistent with the certified values,indicating good accuracy of the method.Inorganic arsenic in rice could be detected using this method without chromatographic separation of different arsenic species.This method was characterized by simple and rapid operation,high sensitivity,good accuracy and high reliability,and applicable for the determination of inorganic arsenic content in rice.