Detailed Hydrocarbon Analysis
The purpose of detailed hydrocarbon analysis (DHA) is to determine the bulk hydrocarbon group type composition (PONA: Paraffins, Olefins, Naphthenes and Aromatics) of gasoline and other spark-ignition engine fuels that contain oxygenate blends (Methanol, ethanol, MTBE, ETBE, and TAME) according to ASTM-D6730. PONA analyte identification is conducted by matching retention indices with normal hydrocarbon paraffins. However, chromatograms obtained in PONA analyses have an extremely large number of peaks and their analytes may be mislabeled. Without accurate and reproducible retention indices, this may result in erroneous PONA ratios. The GC-2030 incorporates an Advanced Flow Controller that enables highly precise flow control, and makes it easy to analyze and identify detailed hydrocarbons. Shimadzu offers DHA analysis conforming to the following methods: ASTM-D5134, ASTM-D6729, ASTM-D6730, and ASTM-D6733.
Example of a DHA analysis chromatogram
Analytical Conditions
| Equipment | PONA System (Nexis GC-2030AF) |
| Column | Rtx-PONA, 100 m x 0.25 mm x 0.5 um |
| Pre-column | Pre-PONA, 2 m x 0.25 mm x 1 um |
| Col. Temp | 5 º C (hold 10 min) → 5 ºC/min → 48 ºC (hold 49 min) → 1.2 ºC/min → 200 ºC (5 min) |
| Carrier Gas | He, Split 1:150 hold 5 min, split 1:20 for the rest time. |
| Sample size | 0.2 uL |
| Injector | 250 ºC |
| Detector | 250 ºC |
| Cryogenic | CRG-2030 with liquid CO2 |
Example of summary report from the dedicated software
| Group Type | Total Mass% | Total Vol.% | Total Mol% |
| Paraffins | 15.868 | 17.1143 | 15.9838 |
| Iso-Paraffins | 19.495 | 20.8586 | 19.1926 |
| Olefins | 17.3556 | 18.5952 | 19.8748 |
| Napthenes | 20.6483 | 20.0522 | 21.3048 |
| Aromatics | 23.5425 | 20.3256 | 21.8861 |
| Total C14+ | 3.0907 | 3.054 | 1.7579 |
| Total Unknowns | 0 | 0 | 0 |
| Total Oxygenates | 0 | 0 | 0 |
| Sample Total | 100 | 100 | 100 |
| Multi-substituted Aromatics: 13.7740 (mass %), 11.8683(vol. %) Average Molecular Weight: 112.8396 Reid Vapor Pressure @ 100F: 1.9378 Calculated Octane Number: 77.0250 |
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| IBP | T10 | T50 | T90 | FBP | |
| BP by mass (Deg. F) | 82.11 | 153.14 | 227.16 | 402.10 | 488.66 |
| BP by vol. (Deg. F) | 82.11 | 146.25 | 274.10 | 401.72 | 488.66 |
| Percent Carbon: 86.7143 Percent Hydrogen: 13.2857 Bromine Number (Calc): 22.8036 |
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Example of summary by group type & carbon number (in Mass Percent)
| Carbon | Paraffins | I-Paraffins | Olefins | Napthenes | Aromatics | Unknowns | Total |
| C1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| C2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| C3 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| C4 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| C5 | 2.61412 | 0.39222 | 2.12534 | 1.02294 | 0 | 0 | 6.15463 |
| C6 | 1.75622 | 1.74186 | 3.4275 | 1.83233 | 1.5174 | 0 | 10.27531 |
| C7 | 1.78205 | 3.41605 | 4.85244 | 3.76943 | 1.02589 | 0 | 14.84587 |
| C8 | 1.68547 | 4.74174 | 2.49244 | 6.10152 | 3.72353 | 0 | 18.74469 |
| C9 | 1.74756 | 5.41724 | 3.0002 |
5.20934
|
5.63764 | 0 | 21.01198 |
| C10 | 1.60532 | 3.77676 | 1.45765 | 1.93379 | 6.87431 | 0 | 15.64782 |
| C11 | 1.56754 | 0.0091 | 0 | 0.01491 | 1.45758 | 0 | 3.04912 |
| C12 | 1.56411 | 0 | 0 | 0.76403 | 3.3061 | 0 | 5.63424 |
| C13 | 1.54563 | 0 | 0 | 0 | 0 | 0 | 1.54563 |
| Total C14+ 3.09070, Oxygenates 0.00000, Total Unknowns 0.00000, Grand Total 100.00000 | |||||||