Introduction
The complex nature of crude oil demands analytical solutions and instrumental methods that will separate and identify the complex chemical profile as well as characterize key chemical functional group class differences between complex samples. Comprehensive two-dimensional gas chromatography (GCxGC) expands the peak capacity of the chromatographic separation thereby increasing resolution and analyte characterization for complicated samples. Time-of-Flight mass spectrometry (TOFMS) offers continuous full range non-skewed mass spectral information and fast acquisition rates ideal for analyte identification of complex mixtures.
This application note shows GCxGC-TOFMS data from the comparative analysis of six light crude oil standards from different global regions. A GCxGC-TOFMS analysis method was developed that utilizes variable modulation to maximize the available peak capacity of the second dimension. Comprehensive two-dimensional chromatography facilitates structured separation of functional group classes within the GCxGC chromatographic plane.The comparisons of light crude oil highlight the differences of key functional groups utilizing the Classifications feature available in ChromaTOF software. Major Classification regions such as alkanes, alkenes, alkynes, alcohols, aldehydes, ketones, alkyl-cyclics, indenes, naphthalenes, thiophenes, and PAHs are shown. The comparison of the chromatographic and peak table data with "Classifications" provides a rapid data analysis technique to evaluate key chemical functional group differences in crude oils from various geographic regions. The data presented in this note illustrate the advantages and benefits of GCxGC-TOFMS as well as a "Classifications" strategy to accurately compare chemical differences between light crude oils from different global regions.
Using classifications for sample profiling
The "Classifications" feature available in the ChromaTOF software was utilized to compare and highlight the differences in key chemical functional group classes between the six different light crude oil standards.
Figure 1. The figure above is a list of the 8 Classification regions used to define the chemical profile of six light crude oil standardsResults
The following two-dimensional contour plots illustrate differences in chemical composition which can be beneficial in differentiation of the light crude oil origin. Table 1 lists the area percent results for each classification that specifically defines each standard. Eight classifications are shown with colored peak markers and labels that represent different chemical and functional group classes. The orthogonal separation system used in GCxGC, provides very structured chromatograms that generate distinct bands of analytes grouped by specific chemical characteristics. This optimized separation illustrates the advantages of GCxGC-TOFMS to provide an informative profile for the chemical composition of light crude oil.
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