Prieto A, Zuloaga O, Usobiaga A, Etxebarria N, Fernández L A, Marcic C, de Diego A
Kimika Analitikoa Saila, Euskal Herriko Unibertsitatea, 644 P.K., Bilbao, Spain.
J Chromatogr A. 2008 Mar 21;1185(1):130-8. doi: 10.1016/j.chroma.2008.01.046. Epub 2008 Feb 1.
In this work, making use of experimental designs, headspace-stir bar sorptive extraction (HS-SBSE) followed by thermal desorption (TD) coupled to a gas chromatography-mass spectrometry (GC-MS) for the simultaneous determination of mercury and tin organometallic compounds present in surface water, sediment and biological tissue was optimized. All solid samples require a previous extraction typically done with diluted HCl or KOH/methanol solutions, and the derivatization, in all the cases, of the organometallic compounds with NaBEt(4). As a consequence, the preconcentration step was carried out in a 0.1 mol L(-1) HOAc/NaOAc buffer solution, with 0.1% (m/v) of NaBEt(4), without the addition of NaCl as a salting out reagent, and with the stir bar (20 mm x 1 mm) located in the headspace (HS). In addition, the desorption step required the following conditions: 250 degrees C (desorption temperature), 15 min (desorption time), 14.1 psi (approximately 97.2 kPa) (vent pressure) and 75 mL min(-1) (vent flow). Finally, to assure the extraction of all the analytes under equilibrium, 5h are required. Inorganic mercury (Hg(2+)) and tripropyltin (TPrT) were used as internal standards to correct for variations in the extraction, derivatization and detection steps. The resulting method provides precise (4-17%) and accurate (against four certified reference materials) results in the ng L(-1) and pg g(-1) range concentrations with recoveries within 80-120% for water samples. The proposed methodology is currently applied in the speciation analysis of specimens obtained in different estuarine sites of the Basque Coast.
在本研究中，利用实验设计，对顶空搅拌棒吸附萃取（HS-SBSE）结合热脱附（TD）与气相色谱-质谱联用（GC-MS）同时测定地表水、沉积物和生物组织中有机金属汞和锡化合物的方法进行了优化。所有固体样品都需要预先用稀盐酸或氢氧化钾/甲醇溶液进行萃取，并且在所有情况下，有机金属化合物都要用四乙基硼酸钠（NaBEt(4)）进行衍生化。因此，预浓缩步骤在0.1 mol L(-1) 醋酸/醋酸钠缓冲溶液中进行，加入0.1%（m/v）的四乙基硼酸钠（NaBEt(4)），不添加氯化钠作为盐析试剂，搅拌棒（20 mm×1 mm）置于顶空（HS）中。此外，脱附步骤需要以下条件：250℃（脱附温度）、15分钟（脱附时间）、14.1 psi（约97.2 kPa）（放空压力）和75 mL min(-1)（放空流量）。最后，为确保所有分析物在平衡状态下被萃取，需要5小时。使用无机汞（Hg(2+)）和三丙基锡（TPrT）作为内标来校正萃取、衍生化和检测步骤中的变化。所得方法在纳克/升和皮克/克浓度范围内提供了精确（4 - 17%）且准确（针对四种有证标准物质）的结果，水样回收率在80 - 120%之间。所提出的方法目前应用于巴斯克海岸不同河口站点采集样本的形态分析。
