Eom In-Yong, Niri Vadoud H, Pawliszyn Janusz
Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada.
J Chromatogr A. 2008 Jul 4;1196-1197:10-4. doi: 10.1016/j.chroma.2008.03.036. Epub 2008 Mar 19.
This paper describes a new approach that combines needle trap devices (NTDs) with a dynamic headspace sampling technique (purge and trap) using a bidirectional syringe pump. The needle trap device is a 22-G stainless steel needle 3.5-in. long packed with divinylbenzene sorbent particles. The same sized needle, without packing, was used for purging purposes. We chose an aqueous mixture of benzene, toluene, ethylbenzene, and p-xylene (BTEX) and developed a sequential purge and trap (SPNT) method, in which sampling (trapping) and purging cycles were performed sequentially by the use of syringe pump with different distribution channels. In this technique, a certain volume (1 mL) of headspace was sequentially sampled using the needle trap; afterwards, the same volume of air was purged into the solution at a high flow rate. The proposed technique showed an effective extraction compared to the continuous purge and trap technique, with a minimal dilution effect. Method evaluation was also performed by obtaining the calibration graphs for aqueous BTEX solutions in the concentration range of 1-250 ng/mL. The developed technique was compared to the headspace solid-phase microextraction method for the analysis of aqueous BTEX samples. Detection limits as low as 1 ng/mL were obtained for BTEX by NTD-SPNT.
本文描述了一种新方法，该方法将针捕集装置（NTD）与动态顶空采样技术（吹扫捕集）相结合，使用双向注射泵。针捕集装置是一根22号不锈钢针，长3.5英寸，填充有二乙烯基苯吸附剂颗粒。使用相同尺寸但未填充的针进行吹扫。我们选择了苯、甲苯、乙苯和对二甲苯（BTEX）的水性混合物，并开发了一种顺序吹扫捕集（SPNT）方法，其中采样（捕集）和吹扫循环通过使用具有不同分配通道的注射泵依次进行。在该技术中，使用针捕集装置依次采集一定体积（1 mL）的顶空；之后，将相同体积的空气以高流速吹扫到溶液中。与连续吹扫捕集技术相比，该技术显示出有效的萃取效果，稀释效应最小。还通过获得浓度范围为1 - 250 ng/mL的水性BTEX溶液的校准曲线进行了方法评估。将所开发的技术与顶空固相微萃取方法进行比较，用于分析水性BTEX样品。通过NTD - SPNT获得的BTEX检测限低至1 ng/mL。
