Determination of the antibiotic fludalanine in plasma and urine by high-performance liquid chromatography using a packed-bed, post-column reactor with o-phthalaldehyde and 2-mercaptoethanol

Fludalanine is a novel anti-bacterial agent active against gram-negative and gram-positive bacteria. A high-performance liquid chromatographic assay has been developed using ion-pair chromatography to resolve fludalanine and the internal standard 3,3-difluoro-D-alanine from plasma and urine background. The mobile phase contains sodium dodecyl sulfonate and methanol in a phosphate buffer. Fludalanine is derivatized post-column with o-phthalaldehyde via a packed-bed chemical reactor. The adduct is detected fluorometrically. The plasma and urine assays are sensitive to 0.25 and 0.5 micrograms/ml, respectively.