Use of a nitrogen detector for GLC determination of fluorouracil in plasma during single- and combined-agent chemotherapy.

A GLC assay for fluorouracil was developed and used to monitor plasma drug levels in patients on both single- and combined-agent chemotherapy. Fluorouracil is extracted from plasma, derivatized by flash methylation, and estimated using a thermionic nitrogen-phosphorus detector. The GLC determination was accurate at concentrations as low as Q.1 microgram/ml of human plasma. Other drugs commonly used in combination with fluorouracil did not interfere with the assay.