Department of Analytical Chemistry, University of Barcelona, Barcelona, Spain.
Electrophoresis. 2011 Aug;32(16):2123-30. doi: 10.1002/elps.201000676. Epub 2011 Jul 18.
Two in-line enrichment procedures (large volume sample stacking (LVSS) and field amplified sample injection (FASI)) have been evaluated for the CZE analysis of haloacetic acids (HAAs) in drinking water. For LVSS, separation on normal polarity using 20 mM acetic acid-ammonium acetate (pH 5.5) containing 20% ACN as BGE was required. For FASI, the optimum conditions were 25 s hydrodynamic injection (3.5 kPa) of a water plug followed by 25 s electrokinetic injection (-10 kV) of the sample, and 200 mM formic acid-ammonium formate buffer at pH 3.0 as BGE. For both FASI and LVSS methods, linear calibration curves (r(2) >0.992), limit of detection on standards prepared in Milli-Q water (49.1-200 μg/L for LVSS and 4.2-48 μg/L for FASI), and both run-to-run and day-to-day precisions (RSD values up to 15.8% for concentration) were established. Due to the higher sensitive enhancement (up to 310-fold) achieved with FASI-CZE, this method was selected for the analysis of HAAs in drinking water. However, for an optimal FASI application sample salinity was removed by SPE using Oasis WAX cartridges. With SPE-FASI-CZE, method detection limits in the range 0.05-0.8 μg/L were obtained, with recoveries, in general, higher than 90% (around 65% for monochloroacetic and monobromoacetic acids). The applicability of the SPE-FASI-CZE method was evaluated by analyzing drinking tap water from Barcelona where seven HAAs were found at concentration levels between 3 and 13 μg/L.
两种在线富集程序（大体积样品堆积（LVSS）和场放大样品进样（FASI））已被评估用于 CZE 分析饮用水中的卤乙酸（HAAs）。对于 LVSS，需要使用 20 mM 乙酸-乙酸铵（pH 5.5）中含有 20% ACN 的正相分离作为 BGE。对于 FASI，最佳条件是 25 s 水相（3.5 kPa）进样，随后是 25 s 电动进样（-10 kV）的样品，以及 200 mM 甲酸-甲酸铵缓冲液，pH 值为 3.0 作为 BGE。对于 FASI 和 LVSS 方法，均建立了线性校准曲线（r(2) >0.992）、在 Milli-Q 水中制备标准品的检出限（LVSS 为 49.1-200 μg/L，FASI 为 4.2-48 μg/L），以及运行间和日间精密度（浓度的 RSD 值高达 15.8%）。由于 FASI-CZE 实现了更高的灵敏增强（高达 310 倍），因此选择该方法用于分析饮用水中的 HAAs。然而，为了优化 FASI 的应用，需要通过 SPE 使用 Oasis WAX 小柱去除样品盐度。使用 SPE-FASI-CZE，可获得 0.05-0.8 μg/L 范围内的方法检出限，回收率通常高于 90%（对于一氯乙酸和一溴乙酸约为 65%）。通过分析来自巴塞罗那的饮用水，评估了 SPE-FASI-CZE 方法的适用性，在该水样中发现了七种 HAAs，浓度在 3 至 13 μg/L 之间。
