Selenium speciation in enriched and natural samples by HPLC-ICP-MS and HPLC-ESI-MS with perfluorinated carboxylic acid ion-pairing agents
Selenium speciation in enriched and natural samples by HPLC-ICP-MS and HPLC-ESI-MS with perfluorinated carboxylic acid ion-pairing agents
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作者：
Kotrebai, M;Birringer, M;Uden, PC
富硒植物，如超积累植物修复植物（干样品中的黄蓍，517 μ g g（-1）Se，芥菜，138 μ g（-1）Se），酵母（1200、1922和2100，μ g g（-1）Se，干样品），斜坡（葱，干样品中硒含量为48、77、230、252、405和524 μ g g g（-1）），洋葱（洋葱，干样品中96和140微克克（-1）硒）和大蒜（Allium sativum，68，112，135，296，1355 μ g g（-1）Se（干样品中）通过HPLC-ICP-MS分析它们在热水和酶提取后的硒含量和形态。还分析了具有天然硒水平的参考样品，例如洋葱和大蒜对照，烹饪大蒜粉，烘焙酵母粉和商业大蒜补充剂。还通过HPLC-电喷雾电离（ESI）-MS检查所选样品。HPLC主要用0.1%七氟丁酸（HFBA）作为离子配对剂在1 + 99 v/v甲醇-水溶液中进行，但也使用0.1%三氟乙酸（TFA）在1 + 99 v/v甲醇-水溶液中进行，以允许对未用HFBA溶解的化合物进行色谱分析。超过75%的总洗脱硒化合物，根据元素特异性检测，从保留时间数据和标准加标实验中确定，60和85%之间的化合物通过MS确定，高达25%的总洗脱分子硒物种尚未确定。HPLC-ICP-MS的定量限（LOQ，定义为S/N为10的浓度）在富硒样品的进样提取物中为2-50 ng mL（-1）Se，在天然硒水平样品中为2-10 ng mL（-1）Se。HPLC-ESI-MS的LOQ值约为1.5。比HPLC-ICP-MS测定值高100倍。
Selenium-enriched plants, such as hyperaccumulative phytoremediation plants (Astragalus praleongus, 517 mu g g(-1) Se, and Brassica juncea, 138 mu g g(-1) Se in dry sample), yeast (1200, 1922 and 2100, mu g g(-1) Se in dry sample), ramp (Allium tricoccum, 48, 77, 230, 252, 405 and 524 mu g g(-1) Se in dry sample), onion (Allium cepa, 96 and 140 mu g g(-1) Se in dry sample) and garlic (Allium sativum, 68, 112, 135, 296, 1355 mu g g(-1) Se in dry sample) were analyzed by HPLC-ICP-MS for their selenium content and speciation after hot water and enzymatic extractions. Reference samples with natural selenium levels, such as onion and garlic controls, cooking garlic powder, baking yeast powder and a commercial garlic supplement were also analyzed. Selected samples were also examined by HPLC-electrospray ionization (ESI)-MS. HPLC was mostly carried out with 0.1% heptafluorobutanoic acid (HFBA) as ion-pairing agent in 1 + 99 v/v methanol-water solution, but 0.1% trifluoroacetic acid (TFA) in 1 + 99 v/v methanol-water solution was also utilized to permit chromatography for compounds that did not elute with HFBA. More than 75% of the total eluting selenium compounds, based upon element specific detection, were identified from retention time data and standard spiking experiments, and between 60 and 85% of compounds were identified by MS, with up to 25% of the total eluting molecular selenium species being unidentified as yet. Limits of quantification (LOQ, defined as the concentration giving an S/N of 10) for HPLC-ICP-MS were in the range 2-50 ng mL(-1) Se in the injected extracts for the selenium-enriched samples and 2-10 ng mL(-1) Se for the natural selenium level samples. LOQ values for HPLC-ESI-MS were ca. 100 times higher than those measured by HPLC-ICP-MS.