Table 1. Some Performance Characteristics of the HPLC-MS/MS Method for Melatonin, l-Tryptophan, and Serotonin.

compound	precursor ion m/z	product ions m/z	tR (min)	linear regression equations	linearity range of response (ng mL–1)	R	LoD (ng mL–1)
melatonin	233.00	174.10	8.60 ± 0.10	A = 6.62428e + 006xC – 675.693	10–5000	0.9999	0.6
		159.10
		130.10
l-tryptophan	205.20	188.10	3.52 ± 0.10	A = 4.52570e + 006xC + 139 057	10–5000	0.9999	0.5
		146.15
		118.10
serotonin	177.2	160.20	2.66 ± 0.03	A = 6.13544e + 006xC + 37 040.6	10–5000	0.9999	0.2
		115.20
		117.10