Liljegren Gustav, Nyholm Leif
Department of Analytical Chemistry, Uppsala University, PO Box 599, SE-751 24 Uppsala, Sweden.
Analyst. 2003 Mar;128(3):232-6. doi: 10.1039/b211398h.
Polypyrrole coated microarray electrodes have been used for electrochemically controlled solid-phase microextraction and preconcentration on individually addressable gold microband electrodes. In this study, a flow of analyte solution was maintained over the band electrodes by positioning a capillary in a vertical position over the electrode array during both the extraction and the detection of the desorbed compounds. This experimental set-up was used to evaluate the possibilities of using electrochemically controlled solid-phase microextraction with conducting polymers as a preconcentration step in miniaturised flow systems. The performance of the polymer, which was prepared by electrochemical polymerisation using a solution of 0.05 M pyrrole and 0.1 M LiClO4, was investigated using chloride as a model analyte employing different extraction times and analyte concentrations. It was found that significant preconcentration was possible using extraction times of only a few minutes and that a good linearity between the extraction time and detection response was present both for mM and microM chloride concentrations. Compared to a recent study (Liljegren et al., Analyst, 2002, 127, 591-597), using a more traditional solid-phase microextraction technique under electrochemical control, the preconcentration factor could be increased by a factor of about 210 by using the present flow system based approach. This increase in the preconcentration factor can be explained by the significant decrease in the desorption volume (i.e. reduced dilution of the desorbed analyte) associated with the use of the present flow system. With the present approach, the detection limit for the model analyte chloride could be decreased from 10 microM to 625 nM employing an extraction time of 180 s.
聚吡咯涂层微阵列电极已用于电化学控制的固相微萃取，并在可单独寻址的金微带电极上进行预富集。在本研究中，在解吸化合物的萃取和检测过程中，通过将毛细管垂直放置在电极阵列上方，使分析物溶液在带电极上保持流动。该实验装置用于评估在小型流动系统中使用导电聚合物进行电化学控制的固相微萃取作为预富集步骤的可能性。使用0.05 M吡咯和0.1 M LiClO4溶液通过电化学聚合制备的聚合物，以氯化物作为模型分析物，采用不同的萃取时间和分析物浓度对其性能进行了研究。结果发现，仅需几分钟的萃取时间就可以实现显著的预富集，并且对于毫摩尔和微摩尔浓度的氯化物，萃取时间与检测响应之间均呈现良好的线性关系。与最近一项研究（Liljegren等人，《分析家》，2002年，127卷，591 - 597页）相比，该研究在电化学控制下使用更传统的固相微萃取技术，通过使用基于本流动系统的方法，预富集因子可提高约210倍。预富集因子的这种增加可以通过与使用本流动系统相关的解吸体积的显著减小（即解吸分析物的稀释减少）来解释。采用本方法，使用180 s的萃取时间，模型分析物氯化物的检测限可从10 μM降至625 nM。
