The research was conducted using gas chromatography coupled with mass spectrometry. For the study, samples of black shale (Kupferschiefer) with diverse pyrolytic parameters were selected from 4 sites within copper mines (Fore-Sudetic Monocline). Each site was represented by six samples. The tested samples showed pyrolytic properties characteristic of type II kerogen (one sample; designation KII), III (one sample; designation KIII) and IV (two samples designated KIV.1 and KIV.2). Each series of samples (6 replicates) was analysed using four methods of preparation (E, EA, EE and EAE). The first common step in each method was the extraction (E) of organic matter. After extraction, asphaltenes (A) were removed from half of the samples, and half of them were esterified (E). A total of 96 samples were analysed; 24 per site tested and 24 prepared by the same method.
Separation of organic compounds was performed using a gas chromatograph (GC 7890A, Agilent Technologies, USA) interfaced to a mass detector (MS 5975c, Agilent Technologies, Santa Clara, CA, USA). The material was injected with an automatic dispenser (7683 Series Injector, Agilent Technologies, Santa Clara, CA, USA). Integration of the chromatograms was performed due to the threshold and peak height, and the coefficients were 15 and 0.01, respectively. Identification of mass spectra was carried out using the Willey spectral library (version 3.2, Copyright 1988-2000 by Palisade Corporation with The Wiley Registry of Mass Spectral Data, 8th Edition, Copyright 2000 by John Wiley and Sons, Inc.) and NIST (version 2.0f The NIST Mass Spectral Search Program for the NIST/EPA/NIH) (Silverstein et al., 2014).
Four XLSX files contain summary data for each method and allow you to view the entire set (24 samples). The remaining tabular data consists of sheets extracted from them, presenting the results for individual samples (96) analyzed using each of the four extraction methods.
(2026-02-11)
