Charles University, Faculty of Pharmacy in Hradec Králové, Department of Analytical Chemistry, Akademika Heyrovského 1203, 500 05 Hradec Králové, Czech Republic.
Charles University, Faculty of Pharmacy in Hradec Králové, Department of Analytical Chemistry, Akademika Heyrovského 1203, 500 05 Hradec Králové, Czech Republic.
J Chromatogr A. 2018 Jun 22;1555:1-9. doi: 10.1016/j.chroma.2018.04.055. Epub 2018 Apr 23.
Online coupling of Lab-In-Syringe automated headspace extraction to gas chromatography has been studied. The developed methodology was successfully applied to surface water analysis using benzene, toluene, ethylbenzene, and xylenes as model analytes. The extraction system consisted of an automatic syringe pump with a 5 mL syringe into which all solutions and air for headspace formation were aspirated. The syringe piston featured a longitudinal channel, which allowed connecting the syringe void directly to a gas chromatograph with flame ionization detector via a transfer capillary. Gas injection was achieved via opening a computer-controlled pinch valve and compressing the headspace, upon which separation was initialized. Extractions were performed at room temperature; yet sensitivity comparable to previous work was obtained by high headspace to sample ratio V/V of 1.6:1 and injection of about 77% of the headspace. Assistance by in-syringe magnetic stirring yielded an about threefold increase in extraction efficiency. Interferences were compensated by using chlorobenzene as an internal standard. Syringe cleaning and extraction lasting over 10 min was carried out in parallel to the chromatographic run enabling a time of analysis of <19 min. Excellent peak area repeatabilities with RSD of <4% when omitting and <2% RSD when using internal standard corrections on 100 μg L level were achieved. An average recovery of 97.7% and limit of detection of 1-2 μg L were obtained in analyses of surface water.
已研究了在线耦合实验室注射器自动顶空萃取与气相色谱的方法。所开发的方法成功地应用于地表水分析，以苯、甲苯、乙苯和二甲苯作为模型分析物。萃取系统由带有 5mL 注射器的自动注射器泵组成，所有溶液和用于形成顶空的空气都被吸入注射器中。注射器活塞具有纵向通道，允许通过转移毛细管将注射器空直接连接到带有火焰电离检测器的气相色谱仪。通过打开计算机控制的夹管阀和压缩顶空来实现气体注入，随后初始化分离。萃取在室温下进行；然而，通过高顶空与样品比 V/V 为 1.6:1 和大约 77%的顶空进样，获得了与以前工作相当的灵敏度。通过注射器内的磁力搅拌辅助，萃取效率提高了约三倍。通过使用氯苯作为内标来补偿干扰。在进行色谱运行的同时，进行了长达 10 分钟以上的注射器清洗和萃取，使得分析时间<19 分钟。在 100μg/L 水平上，通过省略和使用内标校正，获得了<4%的峰面积重复性 RSD 和<2%的 RSD。在地表水分析中，平均回收率为 97.7%，检出限为 1-2μg/L。
