Headspace solid phase microextraction. Dynamics and quantitative analysis before reaching a partition equilibrium
Headspace solid phase microextraction. Dynamics and quantitative analysis before reaching a partition equilibrium
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DOI：
10.1021/ac970024x
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发表时间：
1997-08-15
影响因子：
7.4
通讯作者：
Ai, J
中科院分区：
文献类型：
--
作者：
Ai, J
与传统的静态顶空和吹扫捕集技术相比，固相微萃取 (SPME) 在顶空化学分析中具有显着的优势，即易于使用和出色的重现性。本报告提出了顶空 SPME 过程的理论处理，重点关注凝相/气相和气相/SPME 聚合物两个界面的传质。 SPME 过程的速率决定步骤可以是分析物从凝聚相蒸发到其顶部空间，也可以是分析物从 SPME 聚合物膜表面扩散到其内层。气相中的传质被认为是一个快速过程。数学解提供了一个表达式，该表达式将提取的分析物的量与其在凝聚相中的初始浓度相关联。在所有顶空 SPME 情况下，它们之间都存在正比关系，这种关系表明，一旦 SPME 条件和采样时间保持恒定，在达到分配平衡之前，SPME 定量是可行的。实验提取时间曲线符合理论预测。提取量与初始浓度的数据图显示出良好的线性，采样时间比达到分配平衡所需的时间短得多。
Solid phase microextraction (SPME) has remarkable advantages in headspace chemical analysis over conventional static headspace and purge-and-trap techniques in terms of its ease of use and superior reproducibility A theoretical treatment of the headspace SPME process is proposed in this report that focuses on the mass transfer at the two interfaces, condensed phase/gas phase and gas phase/SPME polymer. The rate-determining step of the SPME process can be either the analyte evaporation from the condensed phase to its headspace or the analyte diffusion from the SPME polymer film surface into its inner layers. Mass transfer in the gas phase is considered a fast process. The mathematical solution provides an expression that correlates the amount of extracted analyte with its initial concentration in the condensed phase. A directly proportional relationship exists between them in all cases of headspace SPME, and this relationship indicates that SPME quantification is feasible before reaching a partition equilibrium once the SPME conditions and the sampling time are held constant. Experimental extraction-time profiles fit the theoretical predictions. Data plots of the extracted amount vs the initial concentration showed excellent linearity with a sampling time much shorter than that required to reach a partition equilibrium.