Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D5442-17 – Standard Test Method Technical Guide
This article provides an overview of ASTM D5442-17, a standard test method for analyzing petroleum waxes by gas chromatography. The method determines the carbon number distribution from n-C17 to n-C44 and calculates the content of normal and non-normal hydrocarbons using internal standardization.
📝 Scope and Applicability
This test method covers the quantitative determination of the carbon number distribution of petroleum waxes in the range from n-C17 through n-C44 by gas chromatography using internal standardization. It also determines the content of normal and non-normal hydrocarbons for each carbon number. Material with a carbon number above n-C44 is determined by its difference from 100% by mass and reported as C45+. This method is applicable to petroleum derived waxes, including blends of waxes, but is not applicable to oxygenated waxes, such as synthetic polyethylene glycols, or natural products like beeswax or carnauba. Additionally, it is not directly applicable to waxes with oil content greater than 10% as determined by Test Method D721.
🔬 Test Method and Instrumentation
Weighed quantities of the petroleum wax and an internal standard are completely dissolved in an appropriate solvent. The analysis is performed using gas chromatography with a wall coated open tube (WCOT) column. The method employs cool on-column injection to introduce the sample at a temperature at or below the boiling point of the most volatile component. The test method references practices such as D4307 for preparation of liquid blends and D4626 for calculation of gas chromatographic response factors. The carbon number distribution is determined from n-C17 to n-C44, and the content of normal and non-normal hydrocarbons is reported for each carbon number. The use of a low-volume connector is recommended to maintain column efficiency.
📊 Calculations and Reporting
This test method provides a quantitative analysis of the carbon number distribution and the normal and non-normal hydrocarbon content. Non-normal hydrocarbons include aromatics, naphthenes, and branched hydrocarbon types. The results are expressed as percentage by mass. The content of C45+ hydrocarbons is calculated by subtracting the sum of n-C17 to n-C44 from 100%. This ensures comprehensive characterization of petroleum waxes for quality control and performance assessment.
| 🟦 Parameter | 📏 Range | 📐 Measurement | 🎯 Target Compounds |
|---|---|---|---|
| Carbon Number Distribution | n-C17 to n-C44 | Normal and non-normal hydrocarbons | Petroleum waxes |
| Residual Hydrocarbons | C45+ | By difference from 100% | All components above n-C44 |
| ⚡ Key Element | 🟦 Description | 📐 Specification |
|---|---|---|
| Injection Technique | Cool on-column injection | Temperature at or below boiling point of most volatile component |
| Column Type | WCOT | Wall coated open tube |
| Application Range | Carbon number | n-C17 to n-C44 |
💡 Tip: Ensure proper dissolution of the internal standard with the sample to achieve accurate quantification. Low-volume connectors help maintain separation efficiency in capillary systems.
⚠️ Warning: This test method is not suitable for waxes with oil content exceeding 10% by Test Method D721. High oil content can cause interference and inaccurate results.
❓ Frequently Asked Questions
🔍 What is the scope of ASTM D5442-17?
The standard covers the quantitative determination of carbon number distribution in petroleum waxes from n-C17 to n-C44 by gas chromatography, including normal and non-normal hydrocarbon content.
💡 What are the limitations of this method?
It is not applicable to oxygenated waxes, natural products like beeswax, or waxes with oil content greater than 10% as per Test Method D721.
⚡ How is the C45+ content determined?
The content of hydrocarbons with