Data for: Development of a method for the measurement of human scent samples using comprehensive two-dimensional gas chromatography with mass detection
Cite this dataset
Pojmanová, Petra; Ladislavová, Nikola; Urban, Štěpán (2022). Data for: Development of a method for the measurement of human scent samples using comprehensive two-dimensional gas chromatography with mass detection [Dataset]. Dryad. https://doi.org/10.5061/dryad.k98sf7m8m
This dataset was used for development of a method for the measurement of human scent samples using comprehensive two-dimensional gas chromatography with mass detection [https://doi.org/10.1016/j.forsciint.2016.09.011].
The dataset contains chromatograms of a model mixture of human scent and chromatograms of the human scent of one volunteer measured on different column setups. Each sample was processed in ChromaToF(version 126.96.36.199) by LECO corp. The processing step was executed at the signal-to-noise (SN) ratio levels 100, 300, and 500 (human scent samples chromatograms).
Chromatographic and mass spectroscopic method
The temperature of the injector was set to 280 °C. The optimized temperature program was: 40 °C—2 min—5 °C/min—320 °C—10 min. The secondary column was heated to a temperature of 5 °C higher than the primary column and the modulator to a temperature of 15 °C higher than the secondary column. In the case of a 15 m primary column instead of 30 m, the temperature program was shortened by 10 min (the final holding of the final temperature was eliminated), and the secondary column was heated 10 °C higher than the primary column. The transfer line was set to 280 °C. The mass detector was in electron ionization (EI) mode with an ionizing electron energy of 70 eV, and the temperature of the ion source was 250 °C. Data collection took place in the Total Ion Current (TIC) mode; in the range of 29–800 m/z, the data collection speed was 200 spectra/s.
Please refer to this article [https://doi.org/10.1016/j.forsciint.2016.09.011] for more details.
Data processing method (ChromaToF, version 188.8.131.52 by LECO corp.)
Within the basic processing method (chromatogram evaluation), the baseline of the chromatogram is calculated, an automatic peak search and a spectrum library search (NIST) are performed and the area/height of individual peaks is calculated for the purpose of quantitative data evaluation. The baseline is calculated so that it is guided through the center of noise (which corresponds to the set value of 0.5) in the default mode, and the smoothing of individual data points is set on "automatically".
Another task is the actual search for peaks belonging to different analytes. It is necessary to enter the expected peak width in the 1st dimension (in our case 18 s). To enter the value, it is advisable to look at the already measured chromatogram and subtract the peak widths in different parts of the chromatogram. It is then best to enter the width of the narrowest of them, as the software looks for peaks 4 times smaller / larger than the specified value. Within the peak settings in the second dimension, the expected width of two-dimensional peaks is entered again (in our case 0.2 s), then the minimum required match of subpeaks for their subsequent combination (in our case 700, which corresponds to 70%), retention shift of individual subpeaks in the 1st and 2nd dimensions ( 0.1 and 0.05 s) and the minimum required signal-to-noise ratio (S/N) of the sub-peaks (corresponding to one-tenth of the signal-to-noise ratio setting for the main peak of the analyte). Furthermore, the integration approach is specified, we used an adaptive approach that provides more accurate results.
Next, you need to enter S/N for the main peak (we used three levels 100, 300, and 500) and the searched mass m/z (we used the entire measured range). You also enter the maximum number of unknown peaks that the software will search for (in our case 1500).
The third task performed within the basic processing method is to search for the similarity of mass spectra with library records. Here you set the search mode (we recommend a combination of normal/forward mode), the number of the most similar records that the library will show, range of masses that the library takes into account (again left blank or given * if we do not want to limit the search), minimum and maximum of the molecular weight of the searched compounds, the so-called mass threshold, which is the lower cut of the mass spectrum for noise elimination (in our case 10, which corresponds to 1% cut), the minimum match of the spectrum with the library record (in our case 800, which corresponds to 80% match; If the match is lower, the library does not automatically assign a label and the peak is marked as unknown). Furthermore, the libraries in which the search takes place are selected - in our case NIST.
The last task of the basic process method is to determine the area under the peak, respectively to determine the height of the peak for the purposes of quantitative evaluation. In the case of non-targeted analysis, it is recommended to enter the abbreviation DT (deconvolved TIC, ie the area is calculated from the whole deconvolved mass spectrum for the given analyte). We used leaving the option to allow the descent of small equestrian peaks to be checked.
Preprocessed samples are stored in text files with a tabulator as a separator.
Ministerstvo Vnitra České Republiky, Award: VI20172020075
Ministerstvo Vnitra České Republiky, Award: VH20182021030
Ministerstvo Vnitra České Republiky, Award: VJ01010123