Hp 5973 mass spectrometer

The phytochemical profile of essential oil samples was determined through GC/MS analysis. An Agilent USB=393752 GC (Agilent Technologies, Palo Alto, CA, USA) connected to an Agilent HP 5973 Mass Spectrometer (mass selective detector) in electron impact (EI, 70 eV) mode was used to obtain GC/MS data. The GC was equipped with a HHP-5MS 5% phenylmethylsiloxane column (capillary column, 30 m × 0.25 mm × 0.25 μm film thickness, Restek, PaloAlto, CA, USA) having an FID detector. Helium gas was used as carrier gas (flow rate 1 mL/min) while a dynamic oven temperature range was used. The initial temperature was retained at 70 °C for 1 min followed by a 6 °C/min increase up to 180 °C. The temperature was again retained for 5 min at 180 °C and then increased at a rate of 5 °C up to 280 °C and retained for 20 min. The samples were injected in a splitless mood (1/1000 in pentane, v/v). The scan range was 50 m/z to 800 m/z. The individual compounds were identified through comparative analysis with their retention times and spectral pattern on the same conditions from our database, NIST libraries as well as Kovat retention indexes (relative calculation with n-alkane series on same columns).

In general, all chemicals were used as received without further purification. The reduction of nitrobenzene was conducted under an Ar atmosphere (1 atm) in a 10 mL (25 mL for gram scale) round-bottomed pyrex glass flask with a sealed spigot and a magnetic stirrer. A purple LED lamp (~400 nm) was used as the light source. In the reaction, the concentration of nitrobenzene was 0.02 mol/L, unless specified otherwise, dissolved in an aqueous solution of PA at a volume ratio of 3:1. The concentration of nitrobenzene was increased 50–fold for the large-scale experiment. The product compositions were analyzed and determined by means of an Agilent HP5973 mass spectrometer and Agilent 1260 high efficiency liquid chromatography. The Agilent Series are equipped with a vacuum degasser, a quaternary pump, an autosampler and a DAD system, connected to a Agilent ChemStation software. A C18 column (250 × 4.6 mm i.d., 5 μm) were used. Flow rate was 1 mL min-1. Detection wavelength was at 280 nm. Solvents that constituted the mobile phase were (A) methanol and (B) water with the volume ratio 50:50.

To isolate A. iva essential oils (AIVO), 100 g of ground leaves were submitted to hydrodistillation for 3 h using a Clevenger-type apparatus. The hydrolat was extracted twice with n-pentane (20 mL), dried over anhydrous sodium sulfate, then concentrated up to 1.5 mL at 35 °C using a Vigreux column and subsequently analyzed [23 (link)]. Analysis of AIVO was performed by gas chromatography-mass spectrometry (GC-MS) using a gas chromatograph HP 6890 interfaced with an HP 5973 mass spectrometer (Agilent Technologies, Palo Alto, CA, USA) with electron impact ionization (70 eV). Separation of the individual compound was achieved by an HP-5MS capillary column (60 m length, 0.25 mm i.d., 0.25 µm film thickness) under the following operating conditions: temperature program: 50 °C (1 min) to 280 °C (8 min) at 5° C/min. Injection temperature: 250 °C; flow rate of the carrier gas helium: 1.2 mL/min; ion source and quadrupole temperatures: 230 and 150 °C, respectively; ionization voltage: 70 eV; mass range: 50–550 u.
The volatile compounds were identified by comparing their retention indices relative to (C₇-C₂₀) n-alkanes with the literature and/or with authentic compounds when available. Further identification was made by matching their mass spectra fragmentation patterns with corresponding data (Wiley 275L and NIST05a libraries) and other published mass spectra [24 ].