Determination of Ibuprofen in Human Plasma by High-Performance Liquid Chromatography

Ibuprofen is being used with increasing frequency in children to control fever. A high performance liquid chromatographic (HPLC) method was developed to measure ibuprofen in small volumes of plasma to conduct pharmacokinetics studies in infants and children. the assay involved precipitation of plasma proteins with 0.5 N perchloric acid in methanol, using isobutyl phenyl acetate as an internal standard. Chromatographic separation was accomplished under isocratic conditions using a reverse-phase ultrasphere C18 column and mobile phase consisting of 53% acetonitrile at a detection wave length of 214 nm. the retention time of ibuprofen and the internal standard was 6.6 and 9.8 minutes, respectively. the method was suitable for quantitation of ibuprofen at. concentrations ranging from 0.25 to 70 mcg/ml. the interday and intraday coefficient of variation at these concentrations was < 5%. The method was used successfully to measure ibuprofen in 100 microliters of plasma samples obtained from infants and children.