Liquid chromatographic method with immunoaffinity column cleanup for determination of ochratoxin A in barley: collaborative study.
A collaborative study was conducted to evaluate a liquid chromatographic (LC) method with immunoaffinity column cleanup for determination of ochratoxin A. The method was tested at 3 concentration levels of ochratoxin A in barley, which represent possible future European regulatory limits. The test portion was extracted with acetonitrile-water by blending at high speed. The extract was filtered, diluted with phosphate-buffered saline (PBS), and applied to an ochratoxin A immunoaffinity column. The column was washed with water and the ochratoxin A eluted with methanol. The solvent was then evaporated and the residue redissolved in injection solvent. After injection of this solution onto reversed-phase LC column, ochratoxin A was measured by fluorescence detection. Eight samples of low level naturally contaminated barley and 2 samples of blank barley (ochratoxin A not found at the limit of detection of 0.2 microg/kg at the signal-to-noise ratio of 3 to 1) were sent, along with ampules of ochratoxin A, calibrant, and spiking solutions, to 15 laboratories in 13 different European countries. Test portions were spiked with ochratoxin A at levels of 4 ng/g, and recoveries ranged from 65 to 113%. Based on results for spiked samples (blind duplicates) and naturally contaminated samples (blind duplicates at 3 levels), the relative standard deviation for repeatability (RSDr) ranged from 4 to 24%, and the relative standard deviation for reproducibility (RSDR) ranged from 12 to 33%. The method showed acceptable within- and between-laboratory precision, as evidenced by HORRAT values, at the low level of determination for ochratoxin A in barley.
Entwisle
A C
AC
Leatherhead Food RA, Surrey, UK.
Williams
A C
AC
Mann
P J
PJ
Slack
P T
PT
Gilbert
J
J
D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D005433:Flour / Q000032:analysis; D001467:Hordeum / Q000737:chemistry*; D007120:Immunochemistry; D007202:Indicators and Reagents; D009183:Mycotoxins / Q000032:analysis*; D009793:Ochratoxins / Q000032:analysis*; D012015:Reference Standards; D013056:Spectrophotometry, Ultraviolet
D007202:Indicators and Reagents; D009183:Mycotoxins; D009793:Ochratoxins; C025589:ochratoxin A