title: Development of stable isotope dilution assays for ochratoxin A in blood samples.
abstract: Two new stable isotope dilution assays were developed for the quantification of ochratoxin A in human blood samples for exposure studies. The methods based on two different sample extraction and cleanup procedures including liquid-liquid extraction with following immunoaffinity chromatography (IA) as well as a dispersive solid-phase extraction (DSPE) method. For detection, LC-MS/MS was applied. For the first time, exact quantitation of the reference compound ochratoxin A was performed by quantitative NMR spectroscopy (qNMR). Additionally, a comparison of different blood-drawing procedures revealed no differences for heparin plasma and serum whereas citrate plasma gave significantly lower results for the mycotoxin. Limits of detection (LOD: 0.02 ng/g (IA) vs 0.03 ng/g (DSPE)), limits of quantification (LOQ: 0.07 ng/g (IA) vs 0.08 ng/g (DSPE)), relative recovery (≥94%), precision, and linearity indicated excellent performance of the developed methods.
authors.affiliation: Technische Universität München, Alte Akademie 10, D-85354 Freising, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Korn
authors.forename: Oliver
authors.initials: O
authors.lastname: Frank
authors.forename: Thomas
authors.initials: T
authors.lastname: Hofmann
authors.forename: Michael
authors.initials: M
authors.lastname: Rychlik
mesh_terms: D002138:Calibration; D002846:Chromatography, Affinity; D002853:Chromatography, Liquid; D006801:Humans; D007201:Indicator Dilution Techniques; D007553:Isotope Labeling / Q000379:methods*; D057230:Limit of Detection; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D009793:Ochratoxins / Q000097:blood* / Q000737:chemistry; D015203:Reproducibility of Results; D052616:Solid Phase Extraction; D013056:Spectrophotometry, Ultraviolet
chemical_list: D009793:Ochratoxins; C025589:ochratoxin A