Immunoaffinity extraction in veterinary residue analysis--a regulatory viewpoint

The utility of immunoaffinity chromatography (IAC) for the purification of veterinary drug residues from extracts of foods of animal origin is widely acknowledged. However owing to the unique nature of the specific antibody reagent used when synthesising an immunosorbent, certain reassurances are needed before an IAC process can be considered an acceptable stage in a routine analytical method. European Community legislation requires applicants for Maximum Residue Limits or national Marketing Authorization for veterinary medicinal products, used in food producing animals, to provide a routine analytical method in accordance with Volume VI of the Rules Governing Medicinal Products in the European Community. In order to ensure the continued supply of immunosorbent material, applicants wishing to use IAC sample clean-up procedures should consider generating the following data: a standard operating procedure (SOP) for antibody production (or cell-line maintenance in the case of monoclonal antibodies), a specifications document of antibody characterisation, an SOP for immunosorbent synthesis, validation of immunosorbent operating conditions and an assessment of its performance criteria. This paper aims to introduce analysts to the technique of IAC and to suggest how those areas of concern highlighted above may be addressed.