Precolumn derivatization procedures using 1,2,4-triazole for the detection and quantitation of sulbactam and clavulanic acid spiked into urine and blood serum at trace levels have been developed. Sulbactam and clavulanic acid produced derivatives which absorbed maximally at 325 and 315 nm, respectively. The methods allow the detection of clavulanic acid and sulbactam down to 0.05 micrograms ml-1 in serum and 0.5 micrograms ml-1 in urine. The relative standard deviation for five replicate analyses of sulbactam and clavulanic acid at a concentration of 20 micrograms ml-1 in serum and urine ranged from 2-6%. In further HPLC experiments with sulbactam in phosphate buffer solution, ampicillin was found as a contaminant (0.5% by mass) in the sulbactam sample provided. The significance of this finding is discussed.