Determination by HPLC of chlortetracycline in pig faeces

An HPLC assay used to determine chlortetracycline (CTC) in pig faeces is reported. Prodigy ODS3 (4.6 x 150 mm) was used for the stationary phase, whereas the mobile phase comprised oxalic acid, sodium oxalate and sodium decane sulfonate (66%)-each of 4 mM, and 34% acetonitrile. The mobile phase was pumped at a flow rate of 1 mUmin. Detection of CTC was by ultraviolet absorbance at 370 nm, and a 20 μL injection volume was used. Recovery from faeces was >90%, and coefficients of variability between runs were <10%. The lowest limit of quantification was 3.5 mg/kg, with an accuracy of <7% error. There was no interference from endogenous materials in the pig faeces, or commonly used antibiotics, and the method is suitable for use In drug disposition studies.