Esi q tof ms spectrometer

An HPLC-ESI-Q-TOF-MS-based qualitative and quantitative analysis of PHT-MLT extracts and melatonin standard was achieved in a tailored method run on an Agilent G3250AA LC/MSD Q-TOF system equipped with an HP 1200 chromatograph and an ESI- Q-TOF-MS spectrometer (Agilent Technologies, Santa Clara, CA, USA). The set was composed of a degasser (G1322A), a thermostated column chamber, an autosampler (G1329B), a PDA detector (G1315D), and a binary pump (G1312C). The analyses were performed in a gradient method on a Zorbax RP 18 (150 × 2.1 mm, dp = 3.5 µm) HPLC column. The composition of gradient and the selected mass spectrometer settings were presented in Table 2.
The quantitative evaluation of the melatonin was performed based on the calibration curve prepared out of 5 solutions by dissolving of the stock solution of 1 mg/mL to 0.02, 0.01, 0.005, 0.0025 and 0.00125 mg/mL to include the range of content of the individual metabolites in the extracts. The R2 value of all of them exceeded 0.998 and the following calibration curve equation was obtained: y = 10201555384 x − 407111.
For the MS/MS spectra, a data-dependent method was constructed which enabled the fragmentation of the two biggest detected peaks in each microscan. After the collection of one spectrum, these two peaks were ignored from fragmentation for the following 0.3 min.

Starting materials were commercially available and analytically pure. Melting points were measured on a YANACO microscopic melting point meter and were uncorrected. ¹H-NMR and ¹³C-NMR spectra were recorded on Bruker AV 300 and Bruker AV 400 spectrometers (Bruker, Karlsruhe, Germany) using TMS as internal standard and CDCl₃ as solvent, respectively. Thin layer chromatographic (TLC) analysis was carried out on silica gel plates GF₂₅₄. High-resolution mass spectra were performed on an ESI Q-TOF MS spectrometer (Agilent, Santa Clara, CA, USA).