Agilent 5975c quadrupole mass spectrometer

Qualitative analysis of the volatile compounds was performed according to a modified method described elsewhere^{69 (link)}. In brief, the analysis was performed using an Agilent 7890 gas chromatograph equipped with a DB-17MS capillary column (30 m × 0.25 mm × 0.25 µm; J&W, Folsom, CA), coupled to an Agilent 5975C quadrupole mass spectrometer (Agilent, Santa Clara, CA). The oven program was as follows: 40 °C for 5 min, 40–70 °C with gradual increase of 2 °C/min, 70 °C for 2 min, 70–120 °C with gradual increase of 3 °C/min, 120–150 °C with gradual increase of 5 °C/min, 150–220 °C at 10 °C/min, and then 220 °C for 2 min. The injector temperature was maintained at 250 °C, and the transfer line temperature was 280 °C. The ion source temperature was 230 °C. The electronic impact (EI) was 70 eV, scanned in the range of m/z 30–300 at a rate of 2.88 scans/s. Helium was employed as a carrier gas, and was introduced at a flow rate of 1 ml/min. A tentative identification of volatile compounds present was achieved by comparing the observed mass spectra with the data system library (NIST2008) and published spectra (Mass Spectrometry Data Center, 1974), supported by retention index data, which were then compared against available literature listing known retention indices (NIST Chemistry WebBook, 2005). All compounds were quantified as 3-octanol equivalents.

Reagents and solvents were purchased from commercial suppliers and used as received. Dry solvents were obtained according to standard procedures. Reactions monitoring, the content of the compounds in fractions during chromatography, and the purity of the target compounds were determined using 7890A gas chromatograph (Agilent Tech., Santa Clara, CA, USA) with an Agilent 5975C quadrupole mass spectrometer as the detector; HP-5 capillary column, He as carrier gas (flow rate 2 mL/min, flow division 99:1). ¹H and ¹³C NMR spectra were recorded on Bruker spectrometers, including an AV-300 instrument at 300.13 MHz (¹H) and 75.47 MHz (¹³C), and an AV-400 instrument at 400.13 MHz (¹H) and 100.61 MHz (¹³C), and a DRX-500 instrument at 500.13 MHz (¹H) and 125.76 MHz (¹³C) in CDCl₃; chemical shifts δ were reported in ppm relative to residual CHCl₃ (d(CHCl₃) 7.24, d(CDCl₃) 76.90 ppm), J in Hz. High-resolution mass spectra (HRMS) were obtained with a DFS Thermo Scientific mass spectrometer in a full scan mode (0–500 m/z, 70 eV electron impact ionization, direct sample administration).

A GC-MS 7890A equipped with an Agilent 5975C quadrupole mass spectrometer controlled by Enhanced ChemStation MSD ChemStation E.01.00.237 (Agilent, Santa Clara, CA) was used to analyze compounds in the extracted volatile oil. Gas chromatography conditions: column was a HP INNOWax (30 m×0.25 mm×0.25 µm), inlet temperature 200°C, column flow 1.0 mL/min, ion source temperature 200°C, injection volume 1 µL and split ratio 10:1. Temperature-programmed conditions: initial temperature 80°C, with 10°C/min rise to 150°C, maintained 1 min, then with 5°C/min rise to 200°C, maintained 3 min, then with 5°C/min rise to 250°C and the carrier gas was He [42] (link)–[44] (link). The content was calculated by peak area normalization method.

Organic compound quantification was performed on the volatile organic compounds (VOCs) benzene, toluene, and o-xylene using EPA Method 1624 [72 ] and selected PCBs (PCB-28, PCB-52, PCB-101, PCB-138, PCB-153, and PCB-180) using EPA Method 1625 [73 ]. Separate analyses were completed for VOC and PCB quantification, each requiring 200 μL of serum spiked with ²H labeled versions of each VOC or ¹³C labeled versions of each PCB. Solid-phase microextraction was performed on the headspace of the samples using a polydimethylsiloxane/divinylbenzene fiber for VOCs and polyacrylate fiber for the PCBs. An automated Gerstel (Linthicum, MD, USA) MultiPurpose Sampler II and Agilent 7890A Gas Chromatography and an Agilent 5975c quadrupole Mass Spectrometer were used for sample analysis and Agilent Chemstation for data analysis. Three independent samples were prepared for each sample, both before and after the cleanroom, with one analysis performed on each.