Msd ion trap xct mass spectrometer

LC-MS characterization of the methanolic extract of Polyalthia longifolia stem bark was realized using a Hewlett-Packard 1100 chromatograph (Agilent Technologies, Santa Clara, CA, USA) with diode array detector (DAD), and equipped with a C₁₈ column (4.6 mm × 150 mm × 5 µm particle size). The mobile phases were 0.1 % formic acid in water (A) and 0.1 % formic acid in methanol (B) at a flow rate of 0.5 ml min⁻¹. The chromatographic method consisted of the following elution gradient: 10 % B for 1.00 min; 10–100 % B for 6.00 min, 100 % B for 1.0 min. An MSD Ion Trap XCT mass spectrometer (Agilent Technologies, Santa Clara, CA) equipped with an electrospray ionization (ESI) interface was used in positive ionization mode (between 100 and 1200 m/z) for the MS analysis using data-dependent automatic switching between MS and MS/MS acquisition modes. Identification of compounds was conducted using a cross comparison of their mass spectra with standards contained in three online spectral databases, namely, spectral database for organic compounds (SDBS) (sdbs.db.aist.go.jp), mass bank Europe (massbank.eu) and metlin database (metlin.scripps.edu).

The putative lipopeptides were identified by HPLC analysis. Briefly, crude extract spots were removed from the TLC plates and dissolved in 10% methanol; the supernatants were analyzed by semipreparative high-pressure liquid chromatography using an Agilent LC 1200 system. The chromatographic separation was performed with a C-18 Column (4.6 × 250 mm). The column outlet was coupled to an Agilent MSD Ion Trap XCT mass spectrometer equipped with an ESI ion source. The lipopeptide fragments were selectively desorbed with methanol gradients from 35% to 65% within 140 min. All elution programs used a flow rate of 0.5 ml/min at 214 nm and detection occurred using the negative ion mode at m/z ranging from 400 to 2000. The isolated fragments were collected for the following experiments.