DETERMINATION OF PIRLIMYCIN RESIDUE IN MILK BY LIQUID-CHROMATOGRAPHICANALYSIS OF THE 9-FLUORENYLMETHYL CHLOROFORMATE DERIVATIVE

A procedure to determine pirlimycin residues in bovine milk was develo ped, Pirlimycin was extracted from milk after protein precipitation an d 2 stages of liquid-liquid partitioning, The extract was evaporated t o dryness, redissolved in dilute base, and derivatized with 9-fluoreny lmethyl chloroformate (Fmoc) to impart a chromophore for ultraviolet ( UV) detection, The derivatized extract was analyzed by reversed-phase liquid chromatography (LC), Pirlimycin concentration was calculated fr om the peak height of the extract by using a linear regression standar d curve prepared from a series of derivatized standards, The procedure 's performance in the range of the regulatory tolerance (0.4 ppm) was validated by replicate analysis of control, fortified control, and res idue-incurred bovine milk, Average recoveries at 0.2, 0.4, and 0.8 ppm were 91, 88, and 87%, respectively, and coefficients of Variation wer e 5, 4, and 1%, respectively, Overall recovery for all samples was 89% , with 4% coefficient of variation, Linear regression analysis of LC/U V results versus results from a previously published LC/mass spectrome tric assay gave a slope of 0.95, with a correlation coefficient of 0.9 8.