This method is for determining total normal paraffins (TNP) and individual normal paraffins in hydrocarbons, such as the UOP Molex process streams, including samples containing the Molex process desorbent. Samples are typically in the C8 to C20 carbon number range. By preheating the sample and adding a suitable solvent, the range can be extended up to C40. The mass-% TNP at the high and low concentrations tend to be biased slightly high because of incomplete compensation for non-normals at the normal paraffin sites. A slightly more accurate TNP value would be expected using UOP Method 411 (see NOTE). The lower limit of detection is 0.01 mass-% for any compound.