Gcms qp

The crude extracts were analyzed with GC-MS/MS (fused silica 15 m × 0.2 mm ID × 1 μm of capillary column, Shimadzu GC-MS QP, Kyoto, Japan) and the sample injection volume was 1 μL. The settings were: initial temperature 30 °C for 2 min, gradual rise to 280 °C and maintenance for 9 min, ionization voltage 70 eV, and mass spectral scan range 25–250 m/z. The GC-MS/MS data were interpreted with the NIST database performed with MMF (minimum match factor, NIST, Gaithersburg, MD, USA) 75 for all the components and also using the virtue of comparisons having more than 62,000 patterns.
MRM/MS analysis was used to detect the antibiotic compound phenazine-1-carboxylic acid (C₁₂H₈N) in the extracts. Agilent 6420 Triple Quad LC/MS system with C18-AR column, 3 µm, 50 × 4.6 mm (MAC-MOD Analytical Inc. Part No. EXL1190546U, MAC-MOD Analytical, Chadds Ford, PA, USA) was used with the mobile phase as acetonitrile-water-trifluoroacetic acid (90:10:0.04, v/v/v) at flow rate 1.0 mL/min and wavelength 248 nm and the sample injection volume was 1 μL.

The DDT was quantified by gas chromatography-mass spectrometry (GC-MS), as described by Baumer et al. (2020) (link). The system consisted of GC-MS (QP) by Shimadzu (Kyoto, Japan), coupled with a mass detector and a capillary column. Detailed specifications were 30 m DB-5, 0.1 μm film thickness, and 0.25 mm internal diameter of the capillary column used for the determination of DDT. Samples were injected using a splitless injection mode while keeping an ion source temperature of 250°C and using helium as the carrier gas at 0.75 ml/min flow rate. The oven temperature was ramped at the rate of 4°C min^–1, initializing its range from 120°C to 190°C, and at the rate of 32°C min^–1 up to 270°C, which was kept constant for 4 min. By operating the mass spectrometer at scanning mode between 45 and 475 Da (m/z), DDT was detected in the sample size of 50 μl with a minimum limit of 1 mg kg^–1.