Agilent 7890a 5975c gc ms system

The extraction and methylation of fatty acids in jujube were conducted according to the method of Song et al. (2019) (link). Fatty acid methyl esters were quantified by an Agilent 7890A-5975C GC–MS system (Agilent Co., CA, USA) equipped with a HP-5MS column (60.0 m × 250 μm, 0.25 μm) column with reference to a fatty acid methyl ester mixed standard. The injection port temperature was 280 °C, the injection volume was 1.0 μL, the split ratio was 20:1, and the carrier gas was He at a flow rate of 1.5 mL/min. The initial column incubator temperature was 120 °C (maintained for 1 min), followed by an increase to 170 °C at a rate of 6 °C/min, 215 °C at 2.5 °C/min (maintained for 12 min), 230 °C at 4 °C/min (maintained for 10 min), and finally to 280 °C at 10 °C/min (maintained for 15 min). The mass spectrometer was set to electron ionization (EI) mode with an ion source temperature of 200 °C, quadrupole temperature of 150 °C, and scanning quality range of 40–550 m/z.

During the embryo-larvae exposure test, solutions were collected for determination of PCB atropisomers at the beginning of treatment and 24 h post exposure. Water samples (1 L) were subjected to five liquid-liquid extractions with n-hexane (100 mL each time) in a separator funnel along with violent shaking. The n-hexane layer was transferred to heart-shaped flasks and concentrated to near-dryness by rotary evaporation (Shanghai Ailang Instruments, Shanghai, China) at 35°C. The concentrated solutions were then blown to dryness by nitrogen evaporation and the residue was again dissolved in 0.1 mL of isooctane for GC-MS analysis.
Twenty embryos or larvae samples in triplicate per treatment were weighed and homogenized with 0.1 mL isooctane using an electric homogenizer (Tiangen Biotech, China). After 20min ultrasonic extraction, samples were centrifuged at 5000 rpm for 10 min. The supernatant after 0.22-μm fiter was for GC-MS analysis.
An Agilent 7890A/5975C GC-MS system equipped with a Chirasil-Dex capillary column (25 m × 0.25 mm; I.D. 0.25 μm df) from Agilent was used for the purity and concentration determinations. The oven temperature was programmed as follows: 60°C for 2 min, 60–150°C at 10°C·min^-1 (held for 5 min), 150–180°C at 1°C·min^-1 (held for 22 min). SIM ions were m/z 360 (quantification ion), 362, and 358 [29 (link)].

The pre-treated samples were analyzed on an Agilent 7890A-5975C GC-MS system (Agilent, USA). All samples were running singly, a quality control (QC) sample made by mixing and blending equal volumes (10 μL) of each fecal sample was used. The raw data obtained from GC-MS runs were analyzed using Agilent Qualitative Analysis version B.07.00 software. Metabolites were identified against the NIST 17 database with a matching score of at least 80. The resulting dataset was normalized to the internal standard before multivariate analysis. Orthogonal partial least squares discriminant analysis (OPLS-DA) was performed to visualize metabolic differences between two groups using the SIMCA version 14.1 software from Umetrics. Metabolic pathway analysis was performed using the online software MetaboAnalyst 4.0 (https://www.metaboanalyst.ca) (14 (link)) based on the Kyoto Encyclopedia of Genes and Genomes (KEGG).

The derivatized sample (1 μL) was injected into an Agilent 7890A/5975C GC-MS system (Agilent, United States) for the profiling analysis and identification of important compounds using a 20:1 split injection ratio. A HP-5 MS capillary column (5% phenyl methyl silox: 30 m × 250 μm i.d., 0.25 μm; Agilent J&W scientific, Folsom, CA, United States) was used. The injection and interface temperatures were 280°C and 150°C, respectively, and the ion source was adjusted to 250°C. The temperature of the transfer line was maintained at 285°C. Separations were achieved using the following temperature program: 5 min isothermal heating at 40°C, followed by a 10°C per min oven ramp to 300°C, and a final isothermal heating at 300°C for 5 min. The linear velocity of carrier gas (helium) was constant at 1 mL/min.
Mass spectra were acquired using full-scan monitoring mode with a mass scan range of 50–500 m/z at a scan speed of 1,000 u/s. The ionization mode was electron impact at 70 eV, and the detector voltage was 0.9 kV (Shen et al., 2015 (link)).

Extraction and sample preparation were performed according to a protocol described previously (Farag et al., 2014 (link)). GC-MS was carried out on the Agilent 7890A-5975C GC-MS system (Agilent, United States). Each 1 μL aliquot of a derivative solution was subjected to analysis. Separation was carried out on a non-polar DB-5MS capillary column (30 m × 250 μm I.D., J&W Scientific, Folsom, CA, United States) with high purity helium as the carrier gas at a constant flow rate of 1.0 mL/min. The GC temperature programming began at 60°C, followed by 8°C/min oven temperature ramps to 125°C, 4°C/min to 210°C, 5°C/min to 270°C, and 10°C/min to 305°C, and a final 3 min maintenance at 305°C. The electron impact (EI) ion source was held at 260°C with a filament bias of -70 V. Full scan mode (m/z 50-600) was used, with an acquisition rate of 20 spectrum/second in the MS setting. To assess for biological variance, eight biological replicates for each sample were extracted, derivatized and analyzed in parallel under identical conditions. A quality control (QC) sample, prepared by mixing aliquots of all the samples, was analyzed using the same method as the analytic samples. The QCs were injected at regular intervals (every 16 samples) throughout the analytical run to provide a set of data from which repeatability could be assessed.

Racemic PCB149 (99.9%) was provided by Dr. Ehrenstorfer GmbH (Germany). The racemate was separated and prepared on a Lux Cellulose-2 column (250 × 4.6 mm, 5 μm, Phenomenex, Torrance, CA) using an Agilent 1200 series high performance liquid chromatography (HPLC) instrument (Wilmington, DE) with 100% n-hexane as the mobile phase at a flow rate of 1.0 mL/min. The enantiomers (−)-PCB149 and (+)-PCB14948 (link) were repeatedly collected separately, concentrated to dryness using a nitrogen-evaporator (Hangzhou Allsheng Instruments company, China) and then dissolved in acetone (Fisher). The purities and concentrations of the isomers were determined by gas chromatography-mass spectrometry (GC-MS).
An Agilent 7890A/5975C GC-MS system equipped with a Chirasil-Dex capillary column (25 m × 0.25 mm; I.D. 0.25 μm df) from Agilent was used for purity and concentration determinations, and the oven temperature was programmed as follows: 60 °C for 2 min, 60–150 °C at 10 °C·min⁻¹ (held for 5 min), 150–180 °C at 1 °C·min⁻¹ (held for 22 min). The SIM ions were m/z 360 (quantification ion), 362, and 3587 (link). The purities of (−)-PCB149 and (+)-PCB149 were higher than >98.0%.