Pegasus 4d tofms

Ten replicates of reconstituted whole aerosol or smoke for each test item, as well as the blank samples and pooled samples, were subjected to GC × GC-TOFMS and LC-HRAM-MS analyses. Both technologies apply a set of diverse analytical methods to ensure the coverage of a wide range of constituent polarities, volatilities, and structural classes. Each aerosol sample was injected once (i.e., no injection replications were performed). Example chromatograms for THS and CC analyzed with all analytical methods are provided in the Electronic Supplementary Material (Fig. S1–S7).
GC × GC-TOFMS analyses comprised a total of three analytical methods (GC Polar, GC-Nonpolar, and GC Volatile) covering different ranges of polarity and volatility. The analyses were performed using a Model 7890A or 8890 gas chromatograph (Agilent Technologies, Santa Clara, CA, USA) equipped with an Auto Liquid Injector (Model 7683 or 7693) and a Thermal Modulator coupled to a Pegasus® 4D TOFMS (LECO Corporation, St. Joseph, MI, USA) for nominal mass (Polar and Volatile method) and to a Pegasus® HRT + 4D for high-resolution accurate mass measurements (Nonpolar method).

The derivatized samples were analyzed using an Agilent 7890 GC system equipped with a Pegasus 4D TOFMS (LECO, St. Joseph, MI) with a DB-5MS capillary column (30 m × 250 μm inner diameter, 0.25 μm film thickness coated with 95% dimethylpolysiloxane cross-linked with 5% diphenyl under the following conditions: initial temperature was kept at 80 °C for 0.2 min, increased to 180 °C at a rate of 10 °C/min, to 240 °C at a rate of 5 °C/min, and further to 290 °C at a rate of 20 °C/min; the column was then maintained for 11 min. One μL of sample solution was injected with helium as the carrier gas at a flow rate of 1 mL/minute. The temperatures of transfer line, and ion source were 245 °C, and 220 °C, respectively. The MS data were acquired with a mass-to-charge ratio (m/z) range of 20−600 in a full-scan mode.

Gas chromatography with time‐of‐flight mass spectrometry system consisting of Agilent 7890 GC system with weak polar capillary column, DB‐5MS (30 m × 250 μm inner diameter, 0.25 μm film thickness), and a Pegasus 4D TOFMS (LECO Corp.) with an electron impact ionization source was employed. Only one‐dimensional GC was used in this study. In the experiment, the electron impact ionization was tuned at 70 eV and helium was used as carrier gas with an average linear velocity of 1.0 ml/min. The mass spectrometer was operated with a transfer line temperature of 270°C, ion source 220°C, and mass range from 50 to 500 amu at a rate of 20 spectra/s after a solvent delay of 370 s. The injection volume was 1 μl, and the temperature of injection was 280°C. The following oven temperature program: set the initial temperature at 50°C with 1 min, then increased to 310°C at a rate of 10°C/min, and hold 8 min (Lisec, Schauer, Kopka, Willmitzer, & Fernie, 2006).

Six biological replicates of each stem sample (0.05 g per sample) of YG689 and ZY821 in the bolting, early flowering, and terminal flowering stages were collected. A total of 36 stem samples were extracted for the GC–TOF–MS analysis, as previously described [64 (link)]. An Agilent 7890 GC system equipped with a Pegasus 4D TOFMS (LECO, St. Joseph, MI, USA) was used for the GC–TOF–MS analysis. Metabolite quantification was performed using a multiple reaction monitoring (MRM) method, as described [65 (link)]. Statistical significance was defined at p < 0.05, with highly significant values at p < 0.01. The VIP (variable importance in the projection) value (threshold > 1) of the first principal component of OPLS-DA model and the p value of the t-test (threshold 0.05) are used to identify the differentially expressed metabolites.

100μl individual knee synovial fluid and 50 μl L-2-chlorophenylalanine (internal standard) were mixed in 1.5 ml tube, extracted by 0.35ml methanol, centrifuged at 10000rpm for 10 min at 4°C. Supernatant was completely dried in a vacuum concentrator. The sample was incubated by 80 μl methoxamine hydrochloride diluted with pyridine to 20 mg/ml at 37°C for 2.5 hr, added 100 μl BSTFA containing 1% TMCS(v/v), and hatched in 70°C for 1 hr, then the sample was analyzed by GC/TOF MS.
Derivative metabolite samples were analyzed by an Agilent 7890 gas chromatograph system (Agilent, USA) coupled to a Pegasus 4D TOF MS (LECO, USA). 1μl aliquot of the samples was injected into a DB-5MS capillary column coated with 5% diphenyl cross-linked with 95% dimethylpolysiloxane (30 m × 250 μm diameter, 0.25 μm thickness) (J&W Scientific, USA) for GC separation. Helium was used as the carrier gas and the flow rate through the column was 1 ml/min. The initial temperature was kept at 90°C for 2 min, then raised to 180°C at a rate of 5°C/min, and finally to 285°C at a rate of 15°C/min. The temperature for injection, the transfer line and ion source was 280°C, 270°C, and 220°C respectively. The energy was -70 eV in electron impact mode. The mass spectrometry data was acquired in full-scan mode with the m/z range of 20–600 at a rate of 100 spectra per second after a solvent delay of 492 s.