Nischwitz Volker, Pergantis Spiros A
Department of Chemistry, Environmental Chemical Processes Laboratory, University of Crete, L. Knossou, Heraklion 71409, Crete, Greece.
Anal Chem. 2005 Sep 1;77(17):5551-63. doi: 10.1021/ac050445b.
The large number of arsenic species known to be present in marine samples and their broad range of chemical properties pose a significant challenge for arsenic speciation analysis. The predominantly used ICPMS detection online with HPLC only provides element-selective information, which is not sufficient for the identification of arsenic species without standards. However, electrospray tandem mass spectrometry in the selected reaction monitoring (SRM) mode enables molecule-selective detection with high sensitivity for quantification. A new HPLC-ES-SRM method was developed for the determination of more than 20 organoarsenic species. Two chromatographic systems were compared, an anion exchange method and a combined cation anion exchange method. Collision-induced dissociation breakdown curves were constructed for all arsenic species investigated and used to optimize the SRM conditions. External calibration was performed with mixed standard solutions containing 21 arsenic species. Two SRM transitions were monitored for most of the analytes, and their intensity ratio was used for quality control. The developed methods were applied for the quantification of arsenic species in extracts of four marine reference materials. Spiking experiments revealed, especially for the early-eluting analytes on the anion exchange system, significant signal suppression by coeluting matrix constituents. Therefore, the standard addition approach was used for quantification. AsB, the major arsenic species in tuna CRM 627 and DORM-2, was accurately quantified with the combined cation anion exchange ES-SRM method.
已知海洋样品中存在大量砷物种，且它们具有广泛的化学性质，这对砷形态分析构成了重大挑战。主要使用的与高效液相色谱联用的电感耦合等离子体质谱检测仅提供元素选择性信息，在没有标准品的情况下，这不足以识别砷物种。然而，处于选择反应监测（SRM）模式的电喷雾串联质谱能够进行分子选择性检测，具有高灵敏度用于定量分析。开发了一种新的高效液相色谱 - 电喷雾 - 选择反应监测方法来测定20多种有机砷物种。比较了两种色谱系统，一种阴离子交换方法和一种阳离子 - 阴离子联合交换方法。为所有研究的砷物种构建了碰撞诱导解离断裂曲线，并用于优化选择反应监测条件。使用含有21种砷物种的混合标准溶液进行外标法校准。对大多数分析物监测两个选择反应监测跃迁，并将其强度比用于质量控制。所开发的方法应用于四种海洋标准物质提取物中砷物种的定量分析。加标实验表明，特别是对于阴离子交换系统上早期洗脱的分析物，共洗脱的基质成分会产生显著的信号抑制。因此，采用标准加入法进行定量分析。使用阳离子 - 阴离子联合交换电喷雾 - 选择反应监测方法准确地定量了金枪鱼标准物质CRM 627和DORM - 2中的主要砷物种——砷甜菜碱（AsB）。
