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Molecularly Imprinted Solid Phase Extraction in a Syringe Needle Packed with Polypyrrole-encapsulated Carbon Nanotubes for Determination of Ochratoxin A in Red Wine

Ottawa-Carleton Chemistry Institute, Department of Chemistry, Carleton University Ottawa, ON K1S 5B6, Canada

Longhui Qiu

Ottawa-Carleton Chemistry Institute, Department of Chemistry, Carleton University Ottawa, ON K1S 5B6, Canada

Jorn C. C. Yu

Ottawa-Carleton Chemistry Institute, Department of Chemistry, Carleton University Ottawa, ON K1S 5B6, Canada

Edward P. C. Lai

Ottawa-Carleton Chemistry Institute, Department of Chemistry, Carleton University Ottawa, ON K1S 5B6, Canada, edward_lai{at}carleton.ca

A novel micro-solid phase preconcentration (µSPP) device is developed by electrochemically depositing molecularly imprinted polypyrrole (MIPPy) over carbon nanotubes (CNTs) packed inside a 22-gauge syringe needle. The ochratoxin A (OTA) template is removed with 1% triethylamine (TEA) in 20:80 v/v acetonitrile—ammonia buffer (20 mM NH₄Cl/NH₃, pH 9.2). This syringe needle is used to extract trace OTA in a red wine sample, and the preconcentrated OTA is eluted with 1% (v/v) TEA in 20:80 v/v acetonitrile—ammonia buffer (20 mM NH₄Cl/NH₃, pH 9.2). The eluate is analyzed by high performance liquid chromatography (HPLC) with fluorescence detection (FD). The results demonstrated a significantly selective enrichment of OTA at sub-ppb levels in the presence of red wine matrix components. Using a sample volume of 0.5mL red wine for preconcentration, it is possible to determine OTA down to a detection limit of 0.04 ng/mL (at 3_B) or a quantification limit of 0.10 ng/mL (at 10_B). The total MIPPy/CNTs-µSPP-HPLC-FD analysis took only 40min, including a µSPP time of 30min, elution time of 20 s, and HPLC analysis time of 10 min. This needle can be reused and hence readily adapted in an autosampler for the processing of multiple samples in series.

Key Words: ochratoxin A • micro-solid phase preconcentration • polypyrrole • carbon nanotubes

Food Science and Technology International, Vol. 13, No. 5, 375-380 (2007)
DOI: 10.1177/1082013207085914


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