Differential pulse polarographic determination of ceftazidime in urine samples with and without prior extraction

Ceftazidime shows two main polarographic reduction peaks at pH 4.0, that at −0.45 V owing to reduction of the CN bond in the methylethoxyimino group and that at −1.00 V owing to the reductive elimination of pyridine: the first peak is particularly suitable for the determination of ceftazidime. Ceftazidime can also be determined indirectly using the tensammetric peak at −0.60 V (in Britton-Robinson buffer pH 9.5) of pyridine liberated on hydrolysis. Ceftazidime can be determined in urine using the direct method only after C18 solid phase extraction, but it can be determined directly in the urine by hydrolysing it and using the pyridine peak.