Article: PDF OnlyQuantitative Determination of Tolazoline in Human Serum by High Performance Liquid ChromatographyTodesco, Liliane M. L.*; Thoma, Jerry J.*; Barth, Richard D.*; Myers, Nancy J.*; White, Robert†; Ward, Robert M.‡Author Information *Department of Toxicology and Therapeutic Drug Monitoring, South Bend Medical Foundation, Inc., †Memorial Newborn Intensive Care, South Bend, Indiana, and ‡Primary Children's Medical Center, Salt Lake City, Utah, U.S.A. Therapeutic Drug Monitoring: March 1987 - Volume 9 - Issue 1 - p 78-84 Buy Abstract A micro high performance liquid chromatography assay is reported for the measurement of tolazoline in newborn infants. Pharmacokinetic data are presented for a single infant receiving tolazoline therapy. Tolazoline and the internal standard, clonidine, are extracted from alkaline serum into butylchloride/isopropanol (95/5). The organic layer is then back extracted with 50 mM phosphoric acid. A portion of the phosphoric acid layer is injected onto a 15-cm CN-bonded phase column. A mobile phase consisting of acetonitrile and phosphate buffer (pH 3) is used to elute tolazoline and the internal standard in < 5 min. The effluent is monitored with a fixed wavelength detector at 214 nm. Using 50 μl of serum, concentrations as low as 0.25 mg/L can be routinely determined with a coefficient of variation (CV) of 7.2%. However, when a 100-μl sample is used, and the injection volume increased, a concentration of 0.05 mg/L can be routinely monitored with a CV of 1.2%. Interference from other drugs that are often used concurrently with tolazoline therapy was not observed. © Lippincott-Raven Publishers.