Sensitive determination of deuterated and non-deuterated indole-3-acetic acid and 5-hydroxyindole-3-acetic acid by combined capillary gas chromatography—negative-ion chemical ionization mass spectrometry

Abstract

Sensitive methods for the determination of deuterated and non-deuterated indole-3-acetic acid and 5-hydroxyindole-3-acetic acid by combined capillary gas chromatography—negative-ion chemical ionization mass spectrometry were developed. Indole-3-acetic and 5-hydroxyindole-3-acetic acids were converted into pentafluorobenzyl and trifluoroacetylmethyl derivatives, respectively, after prepurification by high-performance liquid chromatography. These derivatives were separated by gas chromatography and determined by selected ion monitoring. In the determinations, indole-3-acetic-2,2,2′,4′,5′,6′,7′-d 7 acid and 5-hydroxyindole-3-acetic-3,3-d 2 acid were used as internal standards. The methods developed in this work were used for the determination of deuterated and non-deuterated indole-3-acetic acid and 5-hydroxyindole-3-acetic acid in human urine samples collected before and after administration of l-tryptophan-3,3-d 2.