Automated high-throughput method using solid-phase microextraction-liquid chromatography-tandem mass spectrometry for the determination of ochratoxin A in human urine

A new automated, high-throughput method for the determination of ochratoxin A (OTA) in human urine samples has been optimized and validated using solid-phase microextraction coupled to liquid chromatography-tandem mass spectrometry (SPME-LC-MS/MS). High-throughput was achieved by simultaneous preparation of up to 96 samples using multi-fiber SPME device and multi-well plates. A carbon-tape coating was chosen for the first time as the best extracting phase for this contaminant. The proposed method required only minimal sample pre-treatment to adjust sample pH to 3.0 using a dilution (1:1) with 0.5 M phosphate-buffered saline. A simple gradient guaranteed a good chromatographic separation from matrix interferences in only 8 min. Relative recovery (%), precision and linearity validation results met Food and Drug Administration acceptance criteria at three concentration levels (1, 10, and 50 ng/mL), indicating excellent performance of the proposed method. Limits of detection and quantitation were 0.3 and 0.7 ng/mL in urine, respectively. OTA determination in urine is a good marker for human exposure to this mycotoxin. It is also less invasive than blood analysis. This method is fully automated and the SPME technique is simpler, less time-consuming and cheaper compared with most widely adopted clean-up procedures for OTA extraction from urine. (c) 2008 Elsevier B.V. All rights reserved.