Simple LC method for determination of chloramphenicol in equine, canine, and feline serum

A simple and sensitive high-performance liquid chromatographic (HPLC) method is developed for the determination of chloramphenicol (CAP) concentrations in equine, canine, and feline serum. Serum samples are diluted, then ultrafiltered using a microconcentrator with a 30,000 MW cutoff filter. CAP is separated and quantitated directly from the ultrafiltrate on a reversed-phase column using a buffered methanol mobile phase and a variable wavelength UV detector set at 278 nm. The recovery of CAP from 5 micrograms/mL spiked serum samples is determined using 10 serum samples from each of the three species. This method of sample preparation yields recoveries of 99.8%, 92.0%, and 88.6% with coefficients of variation of 1.2%, 1.3%, and 1.0% in equine, canine, and feline sera, respectively. Concentrations of CAP between 0.5 and 400 micrograms/mL as determined by peak area are found to have a linear relationship (correlation coefficient = 0.99997, n = 10), although amounts as low as 0.025 microgram/mL can be detected.