Highly sensitive and positively charged precolumn derivatization reagent for amines and amino acids in liquid chromatography/electrospray ionization tandem mass spectrometry.

We have developed a highly sensitive and positively charged precolumn derivatization reagent, (5-N-succinimidoxy-5-oxopentyl)triphenylphosphonium bromide (SPTPP), for amines and amino acids in liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS). The handling of the derivatization reaction is quite simple and the reagent reacts with the analytes rapidly and with high efficiency. The derivatized analytes were observed to form regular and intense product ions upon MS/MS analysis; thus, highly sensitive and selective detection was possible in the selected reaction monitoring (SRM) mode. The limits of detection of the SPTPP-derivatized analytes were less than sub-femtomole levels. The sensitivities of the derivatized analytes increased about 500-fold compared to those of underivatized analytes. Since the hydrophobicities of the samples increased after their derivatization, the resolution of the analytes improved dramatically when a reversed-phase system was used. The relative standard deviations of intra-day and inter-day variations were below 10.6% and 13.3%, respectively. The accuracy ranged between 86.6-113% and 83.4-113%, respectively. Furthermore, the developed reagent was used for the analysis of the neurotransmitter 4-aminobutanoic acid (GABA) and oxidative stress markers such as oxidized, nitrated, and halogenated tyrosines in rat serum.