ASTM D4864 Test Method for Determination of Traces of Methanol in Propylene Concentrates by Gas Chromatography
4. Summary of Test Method
4.1 A known mass of water is pressured into a sample cylinder containing a known amount of liquified propylene concentrate. The contents in the cylinder are shaken and the water/methanol phase is withdrawn. A reproducible volume of the extract is then injected into the analytical column of a gas chromatograph (GC) equipped with either a thermal conductivity or a flame ionization detector. The methanol concentration is calculated from the area of the methanol peak using calibration and extraction factors obtained from synthetic blends of known methanol content.
5. Significance and Use
5.1 Methanol is a common impurity in propylene concentrate. It can have a deleterious effect on various processes that use propylene concentrate as a feedstock.
6. Interferences
6.1 There are no known interferences using the GC columns referenced in this test method. However, any water-soluble component that co-elutes with methanol on any other GC column used would interfere.
