Table 1. Showing the Performance of Isotope Abundance Analysis (IAA) and Mass Accuracy Analysis (MAA) in the GC-MS Analysis of Seven Compounds Each at 5 ng on-Column Amount, Using PFTBA Calibration in Profile Mode To Improve the Mass Measurementsa.
| cmpd name, formula, and mass | No. of candidates | meas. MAA error (ppm) | IAA hit #, EFP and EMA | MAA of ±100 ppm hit #, EFP and EMA | IAA ± 0.14 Da mass filter hit #, EFP and EMA | IAA ± 100 ppm mass filter hit #, EFP and EMA |
|---|---|---|---|---|---|---|
| benzene, nitro-C6H5NO2, 123.0315 Da | 78 | 51 | 1, EFP > 78, EMA < 8.3 ppm | 5, FP = 16, EMA = 50 ppm | 1, EFP > 78, EMA < 8.3 ppm | 1, EFP > 507, EMA < 1.3 ppm |
| nicotine, C10H14N2, 162.1151 Da | 241 | 5.1 | 1, EFP > 241, EMA < 5.3 ppm | 2, FP = 121, EMA = 5.3 ppm | 1, EFP > 514, EMA < 2.5 ppm | 1, EFP > 5280, EMA < 0.2 ppm |
| hexadecane, C16H34, 226.2655 Da | 854 | 37 | 2, EFP = 427, EMA = 198 ppm | 1, FP = 854, EMA < 37 ppm | 1, EFP > 17365, EMA < 4.9 ppm | 1, EFP > 364658, EMA < 0.2 ppm |
| anthracene, C14H10, 178.0777 Da | 343 | 24 | 1, EFP > 343, EMA < 4.9 ppm | 6, FP = 57, EMA = 24 ppm | 1, EFP > 521, EMA < 3.2 ppm | 1, EFP > 4706, EMA < 0.4 ppm |
| caffeine, C8H10N4O2, 194.0798 Da | 479 | –1.4 | 1, EFP > 479, EMA < 0.8 ppm | 2, FP = 240, EMA = 1.6 ppm | 1, EFP > 755, EMA < 0.5 ppm | 1, EFP > 5336, EMA < 0.1 ppm |
| methyl stearate, C19H38O2, 298.2866 Da | 2398 | 95 | 7, EFP = 343, EMA = 141 ppm | 5, FP = 480, EMA = 95 ppm | 4, EFP = 600, EMA = 65 ppm | 2, EFP = 1199, EMA = 27 ppm |
| chlorpromazine, C17H19ClN2S, 318.0952 Da | 2896 | 73 | 4, EFP = 724, EMA = 1.5 ppm | 138, FP = 21, EMA = 73 ppm | 4, EFP = 724, EMA = 1.5 ppm | 1, EFP > 4119, EMA < 0.3 ppm |
| descriptive statistics for EMA | avg = 51 ppm, SD = 82 ppm, med = 5.3 ppm | avg = 41 ppm, SD = 35 ppm, med = 37 ppm | avg = 12 ppm, SD = 23 ppm, med = 3.2 ppm | avg = 4.2 ppm, SD = 10 ppm, med = 0.3 ppm | ||
a
Each of the four right-most columns present the results of different analyses, IAA, MAA, IAA + MAA with a ±0.14 Da window and IAA + MAA with a ±100 ppm window. The position of the correct elemental formula in the resulting hit list is shown, and also the EFP and EMA values that are calculated as explained above. The number of candidates are all possible elemental formulae with the same nominal mass and within the following elemental range: O 0-8, N 0-5, S 0-4, P 0-2, Cl 0-2, Br 0-2 (carbon and hydrogen are not restricted). The number of isotopologue peaks used in the evaluation was 4.