Pereira Elisabete A, Cardoso Arnaldo A, Tavares Marina F M
Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil.
Electrophoresis. 2003 Feb;24(4):700-6. doi: 10.1002/elps.200390084.
This work describes a novel approach for the analysis of selected aldehydes (formaldehyde, acetaldehyde, propionaldehyde, and acrolein) and acetone in environmental samples using micellar electrokinetic chromatography (MEKC). The method is based on the reaction of carbonyl compounds with 3-methyl-2-benzothiazoline hydrazone (MBTH) that gives an azine intermediate with maximum absorbance at 216 nm. A systematic evaluation of sample dissolution medium was conducted as a means to enhancing sensitivity. In the best condition, samples were dissolved in 0.030 mol.L(-1) tetraborate solution. This condition presented enhancement factors in the range of 35-54 for the aldehydes under investigation, computed as the improvement of the concentration limits of detection (LODs) with reference to the sample dissolved in pure water. The running buffer was 0.020 mol.L(-1) tetraborate, pH 9.3, containing 0.050 mol.L(-1) sodium dodecyly sulfate (SDS). The overall methodology presented several advantages over established methods for aldehydes. Worthy mentioning that MBTH is available in high purity degree, dispensing laborious reagent purification procedures. A few method validation parameters were determined revealing good migration time repeatability (< 2.5% coefficient of variation, CV) and area repeatability (< 4% CV), excellent linearity (20-120 micro g/L, r > 0.995) and adequate sensitivity for environmental applications. The LODs with respect to each single aldehyde were in the range of 0.54-4.0 micro g.L(-1) and 11 micro g.L(-1) for acetone. The methodology was applied to the determination of aldehydes indoors. Samples were collected in an impinger flask containing 0.05% MBTH solution, at a flow rate of 0.80 L.min(-1), during 2.5 h, at different times during the day. The most abundant carbonyls in the samples were acetone, followed by formaldehyde and acetaldehyde, with estimate peak concentrations of 452, 5.2 and 2.2 ppbv, respectively.
本研究描述了一种采用胶束电动色谱法（MEKC）分析环境样品中特定醛类（甲醛、乙醛、丙醛和丙烯醛）及丙酮的新方法。该方法基于羰基化合物与3 - 甲基 - 2 - 苯并噻唑啉腙（MBTH）的反应，反应生成的嗪中间体在216 nm处有最大吸收峰。为提高灵敏度，对样品溶解介质进行了系统评估。在最佳条件下，样品溶解于0.030 mol·L⁻¹的硼酸盐溶液中。与溶解在纯水中的样品相比，在所研究的醛类中，该条件下的增强因子在35至54之间，以检测限（LOD）浓度的改善来计算。运行缓冲液为0.020 mol·L⁻¹硼酸盐，pH 9.3，含有0.050 mol·L⁻¹的十二烷基硫酸钠（SDS）。与已有的醛类分析方法相比，该整体方法具有多个优点。值得一提的是，MBTH纯度高，无需繁琐的试剂纯化步骤。测定了一些方法验证参数，结果显示迁移时间重复性良好（变异系数CV < 2.5%），面积重复性良好（CV < 4%），线性极佳（20 - 120 μg/L，r > 0.995），对环境应用具有足够的灵敏度。各单一醛类的检测限在0.54 - 4.0 μg·L⁻¹范围内，丙酮的检测限为11 μg·L⁻¹。该方法应用于室内醛类的测定。在一天中的不同时间，以0.80 L·min⁻¹的流速，在装有0.05% MBTH溶液的冲击式吸收瓶中采集样品2.5小时。样品中含量最高的羰基化合物是丙酮，其次是甲醛和乙醛，估计峰值浓度分别为452、5.2和2.2 ppbv。
