Rapid method for accurate analysis of melatonin, serotonin and auxin in plant samples using liquid chromatography–tandem mass spectrometry

Currently, the information available on the physiological functions of melatonin in higher plants is rather limited and the role of plant melatonin in human health remains undetermined. Research in this area has been slow due to lack of efficient analytical methods for rapid identification and quantification of the melatonin and related compounds in complex plant matrices. In this communication, we report the development of a rapid, accurate method for extraction, detection and quantification of plant melatonin, serotonin and indole-3-acetic acid (IAA) by Liquid chromatography–tandem mass spectrometry (LC–MS/MS) with electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photoionization (APPI), respectively. The limit of detection (LOD) of melatonin in the plant extraction was 5 pg/ml and the limit of quantification (LOQ) was 0.02 ng/ml, as well as LOD for serotonin was 100 pg/ml and the LOQ was 5 ng/ml, LOD for IAA was 50 pg/ml and the LOQ was 0.7 ng/ml. There was a linear relationship between melatonin, serotonin, and IAA concentration and peak area over a quantifiable range of 0.02 ng/ml to 0.1 mg/ml, 5 ng/ml to 0.1 mg/ml, and 0.7 ng/ml to 0.1 mg/ml, respectively, in the plant extract.