Determination of roquefortine in blue cheese and blue cheese dressing by high pressure liquid chromatography with ultraviolet and electrochemical detectors.

A method is described for the determination of roquefortine in blue cheese and blue cheese dressing. The method involves sample extraction with ethyl acetate, cleanup by liquid-liquid partition, and determination by high pressure liquid chromatography with ultraviolet and electrochemical detectors connected in series. Recoveries of roquefortine added to cheese at levels of from 16 to 320 ng/g averaged 74.9%. This method was applied to the analysis of 12 samples of blue cheese and 2 samples of blue cheese dressing, all of which were produced in the United States; roquefortine was found in all of the samples at average levels of 424 ng/g for the blue cheese and 45 ng/g for the blue cheese dressing.