Predominant profile: The predominant profile identity is based upon the bulk of the pattern not necessarily on the numerical value of the ion chromatograms.
Hydrocarbon range: The hydrocarbon range is based on the predominant liquid pattern. You will note in this database that there are ranges indicated stating that the majority of the pattern lies between a lower and higher carbon range as indicated by the retention time of normal alkanes. The members of the ILRC have attempted to adopt uniform criteria for assigning the lower and higher ranges. The debate has some proponents indicating that the range begins at the carbon number just before any component peaks are seen and ends after the last component peak has been eluted. Other proponents state that the lower carbon number should be after the pattern begins and end before the final components have eluted so long as the majority (at least 90%) of the pattern lies between the two points. A third takes a variation of the second and assigns a peak height or abundance as a lower threshold. Over time, and as the members of the committee have changed, so too has the prevailing criteria of this determination. If you are utilizing the hydrocarbon range as one of your search criteria, we suggest that you adopt the first option stated above in order to be most inclusive.
Major Peaks: When the highest peak is at 100% relative scale, any peaks higher than 80% are considered as "major peaks". The five highest identifiable peaks are the five "major" peaks used in the database. There may be exceptions where a lesser peak will be identified as a "major" peak when the identity of the compound affects the classification.
Example SRN 355: where a homologous series of normal alkanes which are not dominant by peak height may cause an analyst to vacilate between calling the ignitable liquid as an MPD or naphthenic-paraffinic.
Example SRN 155: where the abundance of alkanes are too significant to ignore and call the ignitable liquid as only an aromatic product.
Miscellaneous: Miscellaneous may be composed of two or more distinct patterns.
Dearomatized: Samples formerly classified as "dearomatized" have been reclassified with the term "dearomatized" included in the supplemental information that can be used in the keyword search.
Blend: Blends are classified as miscellaneous.
• In heavy petroleum distillates, the dominant aromatic compound is approximately 50% or more than the dominant n-alkane compound by peak height (examples: SRN 16 and SRN 118).
• Blends with a heavy component that likely won't be seen in debris without a solvent extraction will be classified as both miscellaneous and by the pattern minus the heavy portion.
• In medium petroleum distillates, it is not uncommon to see elevated aromatics (example: SRN 43 is classified ony as a MPD). The determination of whether an ignitable liquid is a MPD or a blend of a MPD and aromatic is subjective and dependent on the analyst, their training, and laboratory procedures (example: SRN 155 is classified as miscellaneous).
Oxygenated Solvents: One or more of the five major peaks (based on peak height) in the liquid, is an oxygenated compound. It should be noted, if the oxygenated compound is present and is not identified as one of the five major peaks, it will be classified as a Miscellaneous product.
Insecticides: Insecticides are classified based on the solvent vehicle in the product.