Masshunter qualitative analysis navigator b 08

The tentative identification of VOCs was performed using the NIST11.L Mass Spectral database. VOCs whose match with the mass spectra library was less than 50% were discarded, while the rest were evaluated using Agilent MassHunter Qualitative Analysis Navigator B.08.00 software to overlay chromatograms. Those compounds under each condition of the experiment that were only found in one of the three replicates were eliminated. VOCs detected two or more times under the same condition were selected.
Moreover, to identify VOCs exclusively produced by Pc, we removed artifacts such as silicones and column bleeding from our sample analyses. Additionally, volatiles from samples with rice only with either chitosan or buffer were discarded from the samples, assuming that they had not been produced by Pc.
Data were directly calculated from the peak heights of total ion current (TIC) profiles. The remaining VOCs were classified into two groups according to their abundance: major VOCs (peak height ≥ 50,000 ppm) and minor VOCs (peak height < 50,000 ppm).

GC-QTOFMS analysis was performed immediately after the derivatization reactions using an Agilent 7890B-7250 system (Agilent Technologies, Santa Clara, CA, USA) equipped with a HP-5 MS column (30 m × 0.25 mm × 0.25 µm). The sample (0.5 μL) was desorbed in the injection port of the GC at 250 °C. The initial temperature of 50 °C was maintained for 3 min. Then, the oven temperature was increased by 5 °C/min to 280 °C and held at 280 °C for 7 min. The temperature of MS transfer line was set at 280 °C and the temperature of the ion source temperature was set at 200 °C. The ionization potential of MS was 70 eV, the scan range was 50 to 500 m/z and the solvent delay time was 8.0 min.
Data were processed through Agilent Mass Hunter Qualitative Analysis Navigator B.08.00. A NIST 17 library (NIST/EPA/NIH 2017) was used to identify metabolite peaks. The minimum required match factor was 800, and the one-dimensional retention index and exact mass were used to confirm the identified metabolites according to published works [37 (link),38 (link)]. A C8 to C25 standard mixture consisting of n-alkanes was used to compare the retention indices between reference chemicals and samples. Internal standard curves were developed using the semi-quantitative method [39 (link)]. The relative standard deviation (RSD) reflected the reproducibility of all treatments.