Determination of Pimaricin in Cheeses by High Performance Liquid Chromatography

A method was developed for the quantitation of pimaricin in cheese. Ten gram samples were taken from the surface and inner part of the cheese. The samples were each homogenized and extracted with 50ml of a 4:1 mixture of methanol and water. As a preliminary, the UV absorption of the extracts was measured to check whether absorption at 318nm, due to pimaricin, was present. The aqueous methanol extracts were subjected to quantitation by reversed-phase high performance liquid chromatography with a 6:4 mixture of methanol and phosphate buffer (pH 6.8, 0.02M) as the mobile phase. The absorption of 318nm was monitored. The minimum detectable pimaricin concentration in cheese was 0.5μg/g and recovery of pimaricin was determined to be more than 89% when 2μg/g or 10μg/g pimaricin was mixed with pimaricin-free cheese and put through the procedure. Using this procedure, 48 samples of imported cheeses, currently available in Tokyo, were examined for pimaricin content in the surface and inner part. Two cheese samples were found to contain pimaricin in the surface, the contents being 4.6μg/g and 0.7μg/g.