Method

Gas Chromatograph

Chromatec-Kristall 5000/9000

Detector

Flame Ionization Detector (FID)

Column

MXT-1-type capillary column, 30 m × 0.53 mm × 0.25 µm, Restek Cat. No. 70125

Sample Inlet

• 7.3 programmable vaporizing injector

• DAZh-2M or DAZh-2M 3D automatic liquid sampler

Additional Equipment

• Hydrogen generator

• Air compressor

• Gas fittings kit, Part No. 4.078.000

Method Description

ASTM D5442 is used to determine the quantitative carbon-number distribution of petroleum waxes over the range from n-C₁₇ to n-C₄₄. Quantitative analysis is performed using the internal-standard method, with n-C₁₆ (hexadecane) as the internal standard.

In addition to determining the quantitative distribution of n-paraffins (normal alkanes), the method determines the nonparaffinic fraction associated with each corresponding carbon number. The paraffinic and nonparaffinic fractions are separated through chromatogram integration.

The n-paraffin peaks are integrated using the valley-to-valley method, in which only the area of each individual n-paraffin peak is included. The nonparaffinic fraction is integrated using a common baseline.

The portion of the chromatogram above n-C₄₄ is calculated by subtracting the total paraffinic and nonparaffinic fractions from 100% and is reported as C₄₅+.

ASTM D5442 — Standard Test Method for Analysis of Petroleum Waxes by Gas Chromatography