Wang Yi, Luo Jie, Chen Hengwu, He Qiaohong, Gan Nin, Li Tianhua
Institute of Micro-analytical Systems, Department of Chemistry, Zhejiang University, Zijin'gang Campus, Hangzhou 310058, China.
Anal Chim Acta. 2008 Sep 12;625(2):180-7. doi: 10.1016/j.aca.2008.07.030. Epub 2008 Jul 29.
A novel chip-based flow injection analysis (FIA) system has been developed for automatic, rapid and selective determination of dopamine (DA) in the presence of ascorbic acid (AA). The system is composed of a polycarbonate (PC) microfluidic chip with an electrochemical detector (ED), a gravity pump, and an automatic sample loading and injection unit. The selectivity of the ED was improved by modification of the gold working microelectrode, which was fabricated on the PC chip by UV-directed electroless gold plating, with a self-assembled monolayer (SAM) of 3-mercaptopropionic acid (MPA). Postplating treatment methods for cleaning the surface of electroless gold microelectrodes were investigated to ensure the formation of high quality SAMs. The effects of detection potential, flow rate, and sampling volume on the performance of the chip-based FIA system were studied. Under optimum conditions, a detection limit of 74 nmol L(-1) for DA was achieved at the sample throughput rate of 180 h(-1). A RSD of 0.9% for peak heights was observed for 19 runs of a 100 micromol L(-1) DA solution. Interference-free determination of DA could be conducted if the concentration ratio of AA-DA was no more than 10.
一种基于芯片的新型流动注射分析（FIA）系统已被开发出来，用于在抗坏血酸（AA）存在的情况下自动、快速且选择性地测定多巴胺（DA）。该系统由一个带有电化学检测器（ED）的聚碳酸酯（PC）微流控芯片、一个重力泵以及一个自动进样和进样单元组成。通过用3-巯基丙酸（MPA）的自组装单分子层（SAM）修饰在PC芯片上通过紫外光导向化学镀制备的金工作微电极，提高了电化学检测器的选择性。研究了化学镀金微电极表面清洗的镀后处理方法，以确保形成高质量的自组装单分子层。研究了检测电位、流速和进样体积对基于芯片的流动注射分析系统性能的影响。在最佳条件下，在180 h⁻¹的样品通量速率下，DA的检测限为74 nmol L⁻¹。对100 μmol L⁻¹的DA溶液进行19次运行，观察到峰高的相对标准偏差为0.9%。如果AA与DA的浓度比不超过10，则可以进行无干扰的DA测定。
