− | Evaporative loss can affect the appearance of gas chromatograms. When the solvent is removed too fast during recovery of source rock extracts, selective loss of some of the C<sub>15+</sub> components can occur. This loss not only alters the appearance of the gas chromatograms but may also change compound ratios (for example, the pristane–phytane ratio through selective loss of pristane). In some instances, gas stripping in the reservoir can selectively remove lighter components, leaving an oil or residue that looks lightly biodegraded or, in some instances, waxy. | + | Evaporative loss can affect the appearance of gas chromatograms. When the solvent is removed too fast during recovery of source rock extracts, selective loss of some of the C<sub>15+</sub> components can occur. This loss not only alters the appearance of the gas chromatograms but may also change compound ratios (for example, the [[pristane-phytane ratio]] through selective loss of pristane). In some instances, gas stripping in the reservoir can selectively remove lighter components, leaving an oil or residue that looks lightly [http://www.oiltracers.com/services/exploration-geochemistry/oil-biodegradation.aspx biodegraded] or, in some instances, waxy. |