Solid-phase extraction using molecularly imprinted polymer for determination of ochratoxin A in human urine

A rapid, selective and reliable sample preparation technique employing solid-phase extraction (SPE) based on molecularly imprinted polymer (MIP) for the determination of ochratoxin A (OTA) in human urine was described. After sample adjustment to pH 2.5 with 0.1 M HCl, the urine sample was loaded onto the MIP-SPE column, and after a wash step, OTA was eluted for measurement by ultra-high performance liquid chromatography coupled with fluorescence detection. Key parameters which affected the MIP-SPE extraction efficiency were optimized as was the detection method. Under the optimised conditions, the limits of detection and quantification for OTA in urine were 0.2 ng/ml and 0.6 ng/ml, respectively. The recoveries for OTA in urine, spiked at the 0.6, 6.0 and 60 ng/ml levels, ranged from 92.0 to 98.9%. Sixty urine samples were analysed, of which four were found to contain OTA at concentrations ranging from 0.022 to 0.083 ng/ml; the positive results were confirmed by liquid chromatography coupled with tandem mass spectrometry. OTA determination in urine is a good indicator for human exposure to the mycotoxin, and this is the first report on OTA contamination in Chinese people.