ASTM D5134 Standard Test Method for Detailed Analysis of Petroleum Naphthas
ASTM D5134 Standard Test Method for Detailed Analysis of Petroleum Naphthas through n-Nonane by Capillary Gas Chromatography
3. Summary of Test Method
3.1 A representative sample of the naphtha is introduced into a gas chromatograph equipped with a methyl silicone bonded phase fused silica capillary column. Helium carrier gas transports the vaporized sample through the column in which the components are separated. Components are sensed by a flame ionization detector as they elute from the column. The detector signal is processed by an electronic data acquisition system or integrating computer. Each eluting peak is identified by comparing its retention index to a table of retention indices and by visual matching with a standard chromatogram. The table of retention indices has been established by running reference compounds under identical conditions or by gas chromatographic - mass spectrometric (GC/MS) analysis of reference samples under the same conditions, or both.
3.2 The mass concentration of each component is determined by area normalization with response factors. Peaks eluting after n-nonane are summed and reported as C10+.
4. Significance and Use
4.1 A knowledge of the hydrocarbon components comprising a petroleum naphtha, reformate, or alkylate is useful in valuation of crude oils, in alkylation and reforming process control, in product quality assessment, and for regulatory purposes. Detailed hydrocarbon composition is also used as input in the mathematical modeling of refinery processes.
4.2 Separation of naphtha components by the procedure described in this test method can result in some peaks that represent coeluting compounds. This test method cannot attribute relative concentrations to the coelutants. In the absence of supporting information, use of the results of this test method for purposes which require such attribution is not recommended.
5. Interferences
5.1 If present, olefinic hydrocarbons with boiling points less than 150°C will be separated and detected along with the saturates and aromatics. Some of the olefins will coelute with saturates or aromatics and give erroneously high concentrations for those components.
5.2 Alcohols, ethers, and other organic compounds of similar volatility can also interfere by coeluting with saturate or aromatic hydrocarbons thereby causing erroneously high values to be determined.
