COMPARISON AND EVALUATION OF THE SPECIFICITY AND BINDING-CAPACITY OF COMMERCIAL AND IN-HOUSE AFFINITY COLUMNS USED IN SAMPLE PREPARATION FOR ANALYSIS OF GROWTH-PROMOTING DRUGS

Immunoaffinity chromatography (IAC) and affinity chromatography (AC:) are widely used for extraction of drugs from biological samples. Fifte en column types were purchased from five different manufacturers and;t heir ability to bind specific drugs including beta-agonists and anabol ic steroids over a range of analyte concentrations in fortified bovine urine samples was assessed. The performance data obtained from these columns were compared with columns produced in this laboratory (in hou se columns). The in house columns gave the highest recoveries, ranging from 92 to 100% at the 1 ng spiking concentration, for five of the se ven analytes assessed. Forty percent (11 of 27) of all the commercial column assessments recorded recoveries of less than 50% even when the lowest spiking concentration was applied (1 ng). For one manufacturer, only one of seven different columns purchased delivered extraction ef ficiencies greater than 50%. The extraction efficiencies of the clenbu terol columns were the highest with all commercially prepared columns showing at least 50% binding of radiolabelled tracer. Recoveries of al pha-nortestosterone were the lowest. The variability of these products with respect to quality control requires constant monitoring.