Ion‐paired reversed‐phase high‐performance liquid chromatography assay for determination of ceftriaxone in human plasma and urine

A rapid, sensitive, and specific ion‐paired reversed‐phase HPLC assay for ceftriaxone in human plasma and urine is described. Small volumes (50 μL) of sample are deproteinized with acetonitrile and are directly injected on a C₁₈ analytical column. The UV absorbance is monitored at 280 nm. The assay is linear between 1 and 125 μg/mL. of ceftriaxone, with <10% coefficient of both intra‐ and interday variation. Chromatography was specific for ceftriaxone as endogenous compounds and 30 common drugs did not interfere. The assay was used in open heart surgery patients where potential interference from corticosteroids was overcome.