Determination of avilamycin A and B in pig faeces by solid phase extraction and reverse-phase HPLC assay.

A HPLC method is described for the simultaneous determination of avilamycin A and B in pig faeces, following extraction using acetonitrile and normal-phase solid phase extraction. The HPLC stationary phase was Kromosil 5 micro C-18 with a mobile phase of 48% acetonitrile and 52% 0.01N ammonium acetate buffer, pumped at a flow rate of 1 ml/min. Detection was by UV absorbance at 295 nm and an injection volume of 50 microl was used. Recovery from faeces was >98% and intra-assay precision (CV) was <9.0% for both compounds. The lowest limit of quantification was 0.9 mg/kg (avilamycin A) and 0.2 mg/kg (avilamycin B) with an accuracy of <15% error. No interference was seen from endogenous materials in pig faeces and commonly used veterinary antibiotics.