Label-Free Impedimetric Immunoassay for Trace Levels of Polychlorinated Biphenyls in Insulating Oil

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• 作者：Yasumoto Date ; Arata Aota ; Kazuhiro Sasaki ; Yukie Namiki ; Norio Matsumoto ; Yoshitomo Watanabe ; Naoya Ohmura ; Tomokazu Matsue
• 刊名：Analytical Chemistry
• 出版年：2014
• 出版时间：March 18, 2014
• 年：2014
• 卷：86
• 期：6
• 页码：2989-2996
• 全文大小：346K
• 年卷期：v.86,no.6(March 18, 2014)
• ISSN：1520-6882

文摘

A rapid, ultrasensitive, and practical label-free impedimetric immunoassay for measuring trace levels of total polychlorinated biphenyls (PCBs) in insulating oil was developed. First, we developed a novel monoclonal antibody (RU6F9) for PCBs by using a designed immunogen and characterized its binding affinity for a commercial mixtures of PCBs and its main congeners. A micro comblike gold electrode was fabricated, and the antibody was covalently immobilized on the electrode through a self-assembled monolayer formed by dithiobis-N-succinimidyl propionate. The antigen-binding event on the surface of the functionalized electrode was determined as the change in charge transfer resistance by using electrochemical impedance spectroscopy. The resulting impedimetric immunoassay in aqueous solution achieved a wide determination range (0.01鈥?0 渭g/L) and a low detection limit (LOD) of 0.001 渭g/L, which was 100-fold more sensitive than a conventional flow-based immunoassay for PCBs. By combining the impedimetric immunoassay with a cleanup procedure for insulating oil utilizing a multilayer cleanup column followed by DMSO partitioning, an LOD of 0.052 mg/kg-oil was achieved, which satisfied the Japanese regulation criterion of 0.5 mg/kg-oil. Finally, the immunoassay was employed to determine total PCB levels in actual used insulating oils (n = 33) sampled from a used transformer containing trace levels of PCBs, and the results agreed well with the Japanese official method (HRGC/HRMS).