J w db 624

A hyphenated analytical tool of headspace (Agilent 7697A, CA, USA) coupled with gas chromatography-mass spectrometry was used to identify volatile compounds released from the heated vinegar samples (15 mL) in 20 mL screw-cap vials. The sample vials were sealed and thermally heated at 80 °C for 30 min in a closed system. The temperature of the loop and transfer line in the headspace were maintained at 90 °C and 110 °C, respectively. A gas chromatography (Agilent 8890) integrated with a mass analyzer (Agilent 5977 MSD) was then used to analyze the released compounds. The temperature of the injection port was set at 220 °C and configured for split mode at the ratio of 10:1. The oven temperature was started at 40 °C and held for 5 min, increased to 230 °C at 10 °C/min, maintained at 230 °C for 10 min, and heated to 260 °C. The scan range of m/z was 30–350 amu. Helium was used as the carrier gas at 1 mL/min. A nonpolar column (Agilent J&W DB-624) with the dimension of 0.25 mm ID × 60 m L × 1.4 µm thickness was used for compound separation. The ion source of the mass detector was the electronic impact (70 eV) with a source temperature of 230 °C and quadrupole temperature of 150 °C. The other setting parameters were solvent delay, 4.4 min; stop time, 10 min; and scan speed, 1562.

A GC-2010 gas chromatographic system (Shimadzu, Kyoto, Japan) coupled with an electron capture detector was utilized throughout this study. HS sampling was performed using an AOC-5000 combiPal autosampler controlled using the GC-solution software (vs 2.3). The analytes were separated on an Agilent J&W DB-624 (30 m × 0.32 mm, 1.8 μm film thickness) (Part No 123–1334, SN: USD222531H) capillary column containing 6% cyanopropyl/phenyl and 94% polydimethylsiloxane stationary phase. High-purity helium gas (99.999%) was used as the carrier gas at a constant flow rate of 1.5 mL min⁻¹. The injector temperature was kept at 150 °C, while the split ratio was 1:10. The oven temperature was maintained at 35 °C for the first 25 min and was then linearly increased up to 240 °C and held at 2 min. The temperature of ECD was set at 280 °C. High-purity N₂ (99.999%) was used as a make-up gas at a flow rate of 30 mL min⁻¹.
For HS sampling, a 2.5 mL glass syringe was utilized, which is thermostated at 115 °C. The sample volume was 1 mL, and the sample was incubated at 120 °C for 5 min. The sample was agitated at 250 rpm. The aspiration and the injection speed were 100 and 500 μL min⁻¹, respectively.

The Agilent GC-7890A (Santa Clara, CA, USA) was equipped with FID and FPD for the analysis of major constituents and structurally relevant impurities. The chromatographic columns used were Agilent J&W DB-1 (30 m × 0.32 mm × 1.00 μm) and DB-5 (30 m × 0.25 mm × 0.25 μm). The Agilent GC-6890N (Santa Clara, CA, USA) was equipped with an FID and a G1888-headspace injector for quantifying residual organic solvents. The chromatographic column used was an Agilent J&W DB-624 (30 m × 0.32 mm × 1.80 μm). The Thermo Q Exactive Plus (Waltham, MA, USA) was equipped with a heated electrospray ionization source (HESI) for the mass spectrometric characterization of TnPP.
Bruker AVANCE III 400 MHz NMR (Billerica, MA, USA) was used for characterization and quantification. Data processing was conducted using Bruker NMR software TopSpin 3.1.
Water content was determined using a METTLER TOLEDO C30S Karl Fischer titrator (Greifensee, Switzerland). Inorganic impurities were analyzed and determined using an Agilent 8800 ICP-MS (Tokyo, Japan). The samples were weighed using a METTLER TOLEDO XP205 or UMX2 balance (Greifensee, Switzerland). A Vortex-Genie2 vortex oscillator G560E was used to prepare homogenized process solutions (Scientific Industries, Inc., Bohemia, NY, USA).