DETERMINATION OF PIROMIDIC ACID RESIDUES IN TROUT MUSCLE-TISSUE AND IN URINE BY LIQUID-CHROMATOGRAPHY WITH POSTCOLUMN MODIFICATION OF PH AND FLUOROMETRIC DETECTION

A rapid high-performance liquid chromatographic method has been develo ped to determine piromidic acid in trout muscle tissue and in urine, i n the presence of nalidixic, 7-hydroxymethylnalidixic, oxolinic and pi pemidic acids and cinoxacin. A Nova-Pak C-18 column was used with acet onitrile-4.10(-4) M oxalic acid (40:60, v/v) as the mobile phase. A po st-column change of pH was made with NaOH. Fluorimetric detection at 4 56 nn (lambda(ex) 275 nm) was used. The instrumental detection limit w as 5.91 ng/ml, based on height of peak. Pretreatment of the urine samp les was not necessary and fish samples were extracted with sodium hydr oxide solutions and cleaned by means of an extraction with chloroform. Detection limit was 147 ng/ml for urine and 5.91 ng/g for trout muscl e. Good separation without interference from any other components was obtained. Recovery was better than 87% in urine and better than 72% in trout muscle tissue. (C) 1998 Elsevier Science B.V. All rights reserv ed.