Identification and Quantification of Arsenolipids Using Reversed-Phase HPLC Coupled Simultaneously to High-Resolution ICPMS and High-Resolution Electrospray MS without Species-Specific Standards
Identification and Quantification of Arsenolipids Using Reversed-Phase HPLC Coupled Simultaneously to High-Resolution ICPMS and High-Resolution Electrospray MS without Species-Specific Standards
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DOI：
10.1021/ac2005873
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发表时间：
2011-05-01
影响因子：
7.4
通讯作者：
Feldmann, Joerg
中科院分区：
文献类型：
--
作者：
Amayo, Kenneth O.;Petursdottir, Asta;Feldmann, Joerg
尽管几十年来人们就知道砷会形成脂溶性砷化合物，但直到最近才通过结合分馏、元素和分子质谱分析来鉴定这些化合物的尝试取得了成功。在这里，我们表明，使用反相高效液相色谱（RP-HPLC）同时在线耦合高分辨率电感耦合等离子体质谱（ICPMS）和高分辨率电喷雾质谱（ES-MS）可以直接鉴定和定量生物提取物中的砷脂，而无需可用的亲脂性砷标准品。使用甲醇梯度进行分离使得有必要使用梯度相关的砷响应因子来定量提取物中的脂溶性砷物质。响应因子是通过使用已知砷浓度的ICPMS信号获得的。砷响应用于确定不同砷物种的物种特异性响应因子。利用砷物质的保留时间来挖掘 ES-MS 数据以获得精确质量及其串联质谱 (MS/MS) 碎片模式，以提供分子式和结构信息。在毛鳞鱼（Mallotus villosus）鱼粉的己烷相中发现的大多数砷脂是以三种二甲基胂酰烃（C23H38AsO、C17H38AsO、C19H42AsO）的形式存在，并含有少量二甲基胂酰脂肪酸（C17H36AsO3、C23H38AsO3、 C24H38AsO3)。这项工作首次鉴定出脂肪酸链中碳原子数为偶数的二甲基胂酰脂肪酸（C24H38AsO3）。这种分子式很不寻常，与之前发现的所有碳原子数为奇数的含砷脂肪酸不同。
Although it has been known for decades that arsenic forms fat-soluble arsenic compounds, only recent attempts to identify the compounds have been successful by using a combination of fractionation and elemental and molecular mass spectrometry. Here we show that arsenolipids can directly be identified and quantified in biological extracts using reversed-phase high-performance liquid chromatography (RP-HPLC) simultaneously online-coupled to high-resolution inductively coupled plasma mass spectrometry (ICPMS) and high-resolution electrospray mass spectrometry (ES-MS) without having a lipophilic arsenic standard available. Using a methanol gradient for the separation made it necessary to use a gradient-dependent arsenic response factor for the quantification of the fat-soluble arsenic species in the extract. The response factor was obtained by using the ICPMS signal of known concentration of arsenic. The arsenic response was used to determine species-specific response factors for the different arsenic species. The retention time for the arsenic species was utilized to mine the ES-MS data for accurate mass and their tandem mass spectrometry (MS/MS) fragmentation pattern to give information of molecular formula and structure information. The majority of arsenolipids, found in the hexane phase of fish meal from capelin (Mallotus villosus) was in the form of three dimethylarsinoyl hydrocarbons (C23H38AsO, C17H38AsO, C19H42AsO) with minor amounts of dimethylarsinoyl fatty acids (C17H36AsO3, C23H38AsO3, C24H38AsO3). One of the dimethylarsinoyl fatty acids (C24H38AsO3) with an even number of carbon in the fatty acid chain, was identified for the first time in this work. This molecular formula is unusual and in contrast to all previously identified arsenic-containing fatty acids with odd numbers of carbon.