Data for: Application of the Expert Algorithm for Substance Identification (EASI) to Electron Ionization Mass Spectra of n-Alkanes from Different Instruments

Description

Excel spreadsheet of 3,303 mass spectra of n-alkanes ranging from nC8-nC30. The spectra were collected on 4 different different GC-MS instruments; three of which were Agilent and one of which was a Perkin Elmer. This data can be used to test mass spectral algorithms for the identification of spectrally similar substances in the absence of chromatographic data. The spectra contain variance within instruments (caused by time) and variance between instruments.

Steps to reproduce

Conditions for data acquisition are provided in the publication. In short, In labs 1 and 2, replicate EI-mass spectra for the alkanes n-C7–n-C30 were collected on three GC-MS instruments using n-alkane mixes from Sigma-Aldrich (St. Louis, MO). Solutions were diluted in pentane to ~100 ppm of each n-alkane before injection. Lab 1 used an Agilent Technologies (Santa Clara, CA) 7890B GC equipped with an Agilent HP-5 column (30 m x 0.25 mm x 0.25 µm film thickness) and an Agilent 5977 mass spectrometer detector (MSD). Lab 1 also employed a PerkinElmer Clarus 680 GC with a SQ8S MS detector (Waltham, MA). Lab 2 also used an Agilent Technologies 5977 GC-MS instruments with an HP-5 column (30 m x 0.25 mm x 0.25 µm film thickness). For both labs, the injection volume was 1 μL, the electron ionization source temperature was typically set to 230 °C, and the quadruple temperature was typically 150 °C. In lab 1, the data were collected over a period of ~10 years using a variety conditions, but the conditions were typically as follows: 1 µL injection volume; 250℃ injection temperature; 1:20 split ratio; the oven had a starting temperature of 50℃ (2 min hold), then ramped up to 280℃ at 15℃/min and held for 5 min. Helium was used as the carrier gas with a flow rate of 1.8 mL/min and the transfer line was set at 270℃. The mass spectrometer typically had a solvent delay of 1.5 min and a scan range of m/z 30-450. Data for Lab 3 was taken from the publicly available database of the ignitable liquid reference collection (ILRC), which is administered by the National Center for Forensic Science (NCFS) at the University of Central Florida. In lab 3, spectra of n-alkanes were extracted from chromatograms of light, medium, and heavy petroleum distillates that showed adequate resolution from nearby impurities. In this lab, 20 μL of each petroleum distillate was dissolved in 1 mL of carbon disulfide before injection. Data were collected on an Agilent Technologies 6890 gas chromatograph and 5973 mass spectrometer equipped with an HP1 column (0.5 μm x 0.2 mm x 25 m). Separation employed helium at 0.8 mL/min with a split ratio of 50:1 into an injection port at 250 °C. The oven was held at 50 °C for 3 mins before a 10 °C /min ramp from 50-280 °C and a final hold time of 4 mins. The transfer line was held at 280 °C, and the scan range was m/z 30-350. Replicate mass spectra were extracted from Agilent's propriety ".D" raw files at each scan across each GC peak, which resulted in 6-12 partially independent spectra for each n-alkane from each data file. By taking each mass spectrum across each GC peak, one ensures that spectra include variance caused by changes in absolute abundance within and between scans and the effects of spectral skewing.

Institutions

• West Virginia University

  WV, Morgantown

Categories

Funders

• National Institute of Justice

  United States Department of Justice

  District of Columbia, United States

  Grant ID: 15PNIJ-24-GG-03856-RESS

Licence