Jms gc mate 2

NMR spectra were acquired on a Varian Unity INOVA at 400 MHz (¹H) and 100 MHz (¹³C). The major volatile compound was identified based on NMR spectroscopy (¹H, ¹³C, COSY, HSQC, HMBC, Varian, Santa Clara, CA, USA).
Analyses by GC/MS were carried out in an Agilent 7890 A series gas chromatograph (Agilent Technology, Palo Alto, CA, USA) coupled with a JEOL JMS-GC Mate II mass spectrometer (JEOL USA, Peabody, MA, USA). Compounds were separated on an Agilent Technology DB-5MS (30 m × 0.25 mm, film thickness 0.25 μm) capillary column, using the following GC oven temperature program: 1 min at 40 °C, followed by 8 °C/min up to 300 °C, held for 6 min. Helium was used as the carrier gas at a flow rate of 1 mL/min. The electronic ionization energy was 70 eV, and the mass range scanned was 1–600 uma. Scan rate was 1 spec/s. Transfer line and ionization chamber temperatures were 300 °C. Data acquisition and processing were performed with TSS pro 3.0 software system (Shrader Analytical and Consulting Laboratories, Detroit, MI, USA); mass spectra were compared with the National Institute of Standards and Technology-2 (NIST-2) data base. The components were identified based on the comparison of the relative retention indices calculated using a series of n-alkanes (C-8–C-20) and the mass spectra from the spectrometer database (NIST library), followed by comparison with published data.

DI-EI-MS analysis was performed according to our previous report [20 (link)]. In the present study, the electrons were accelerated at 70 eV in the region between the filament and the entrance to the ion source block. EI-MS was conducted using a double-focusing mass spectrometer (JMS GC-mate II; JEOL, Tokyo, Japan) equipped with a heated direct-injection sample probe. The MS detector parameters used were as follows: interface temperature, 320 °C; ion-source temperature, 280 °C; ionization mode, EI; electron energy, 70 eV; scan speed, 0.3 s/scan; interdelay, 0.2 s; scan range, m/z 50−500; accelerating voltage, 2500 V; ionization current (emission), 0.3 mA; and variable temperature duration, 0.5−2.5 min. A 1 μL aliquot of the test sample in water (5 mg/mL) was injected into the DI-EI-MS system. A microsyringe was used to load a drop (1 μL) of each extract solution onto a glass target, which was then loaded into the direct-injection sample probe (MS-DIP25). The integration analysis covered the range of approximately scans 120−360 of the total ion chromatogram (TIC). The TIC was monitored for 2.5 min, and all of the fragment ions between 0.8 and 2.5 min were added.