ASTM D5442 Test Method for Analysis of Petroleum Waxes by Gas Chromatography
4. Summary of Test Method
4.1 Weighed quantities of the petroleum wax and an internal standard are completely dissolved in an appropriate solvent and introduced into a gas chromatographic column that separates the hydrocarbon components by increasing carbon number. The column temperature is linearly increased at a reproducible rate until the sample is completely eluted from the column.
4.2 The eluted components are detected by a flame ionization detector and recorded on a strip chart or computer system. The individual carbon numbers are identified by comparing the retention times obtained from a qualitative standard with the retention times of the wax sample. The percent of each hydrocarbon number through C44 is calculated via internal standard calculations after applying response factors.
4.3 For samples with final boiling points greater than 538°C complete elution of all components may not be achieved under the specified conditions. For this reason, the C45+ material is determined by summing the concentrations of each individual carbon number through C44 and subtracting this total from 100 mass %.
5. Significance and Use
5.1 The determination of the carbon number distribution of petroleum waxes and the normal and non-normal hydrocarbons in each can be used for control of production processes as well as a guide to performance in many end uses.
5.2 Data resulting from this test method are particularly useful in evaluating petroleum waxes for use in rubber formulations.
