Lichens as bioindicators of monitoring of the selective air pollution, Zaabrze (Poland) - chromatograms of GC-MS

Detailed geochemical analyses were performed on 21 powdered samples after their extraction using ultrasound Elmasonic Easy with a dichloromethane (DCM) and methanol (MeOH) mixture (1:1 vol). Extracts were separated into aliphatic-, aromatic-, semipolar- and polar fractions by column chromatography. Silica-gel was first activated at 120 °C for 24 h, cooled, and poured into Pasteur pipettes. Foour eluents were used for fraction collection, namely, n-pentane for the aliphatic fraction, n-pentane and DCM (7:3) for the aromatic fraction, acetone and DCM (1:1) for the semipolar fraction, and DCM and methanol (1:1) for the polar fraction. The semipolar - and polar fraction was derivatized with MTBSTFA (N-tertbutyldimethylsilyl-N-methyltrifluoroacetamide). Samples were derivatized with MTBSTFA dissolved in super-dehydrated n-hexane, and heated at 70 °C for 3 h. The composition of the separated extracts was analyzed by gas chromatography–mass spectrometry (GC–MS) using an Agilent gas chromatograph 7890A coupled with a mass spectrometer 5975C XL MDS. A DB-5UI column was applied (60 m × 250 μm id, 0.25 μm stationary phase film), with He (purity of 99.9999%) as a carrier gas. The experimental conditions were as follows: injection volume of 1.5 μL; split/splitless mode; initial temperature of 45 ◦C (isothermal for 1 min); heating rate up to 100 ◦C at 20 ◦C/min, then 3 ◦C/min to 280 ◦C for 66.25 min. The mass spectrometer worked in electron ionization (EI) mode at 70 eV in full scan mode and scanned from 50 to 650 Da.
Dr Ewa Szram, employed at the Institute of Earth Sciences, Faculty of Natural Sciences, Silesian University in Katowice, carried out the project. This research was funded by the National Science Centre, Poland MINIATURA-6 2022/06/X/ST10/00338 “Lichens as bioindicators of monitoring of the selective air pollution”