Abstract: | A method for the quantification of phenylalanine in whole blood and plasma by isotope dilution gas chromatography—mass spectrometry is presented. The use of an uncommon derivative allows a simple extraction procedure and the most basic mass spectrometer. The relative standard deviation was found to be 1.3% within-batch and 2.1% between-batch under optimum conditions, and the detection limit was found to be 7 pmol injected. The ruggedness of the procedure and sample handling conditions were also examined. |