Two-dimensional thin-layer chromatographic method for the analysis of Ochratoxin A in green coffee

A low-cost thin-layer chromatographic method has been developed for the presumptive measurement of ochratoxin A (OTA) at 5 microgram/kg in green coffee beans. The analytical method consisted of extracting OTA by shaking the beans with a mixture of methanol and aqueous sodium bicarbonate solution, wh...

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Bibliographic Details
Published in:Journal of food protection 2005-09, Vol.68 (9), p.1920-1922
Main Authors: Ventura, M, Anaya, I, Broto-Puig, F, Agut, M, Comellas, L
Format: Article
Language:English
Subjects:
Biological and medical sciences
Chromatography, Thin Layer - methods
Coffee - chemistry
coffee beans
Coffee, tea and other stimulative beverage industries
Consumer Product Safety
Dose-Response Relationship, Drug
food contamination
Food Contamination - analysis
Food industries
food pathogens
Food toxicology
Fundamental and applied biological sciences. Psychology
maximum residue limits
microbial contamination
microbial detection
ochratoxin A
Ochratoxins - analysis
Reproducibility of Results
Sensitivity and Specificity
thin layer chromatography
Time Factors
toxigenic strains
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Summary:A low-cost thin-layer chromatographic method has been developed for the presumptive measurement of ochratoxin A (OTA) at 5 microgram/kg in green coffee beans. The analytical method consisted of extracting OTA by shaking the beans with a mixture of methanol and aqueous sodium bicarbonate solution, which was then purified by liquid-liquid partition into toluene. OTA was separated by normal-phase two-dimensional thin-layer chromatography and detected by visual estimation of fluorescence intensity under a UV lamp at 365 nm. The chromatography solvents were toluene-methanol-formic acid (8:2:0.03) for the first development and petroleum ether-ethyl acetate-formic acid (8:10:1) for the second dimension development. This method was tested with uncontaminated green coffee bean samples spiked with an OTA standard at four different concentrations (5, 10, 20, and 30 microgram/kg). The method is rapid, simple, and very easy to implement in coffee-producing countries. It is highly selective and does not involve the use of chlorinated solvents in the sample extraction step. This inexpensive method has been applied to different types of green coffee samples from various countries (Zimbabwe, Brazil, India, Uganda, Colombia, and Indonesia) and different manufacturers, and no OTA below the detection limit of 5 microgram/kg was detected in any samples analyzed.
ISSN:0362-028X
1944-9097
DOI:10.4315/0362-028X-68.9.1920