Characterization of the Composition of Paraffin Waxes on Industrial Applications

The use of industrial paraffin depends upon the properties that are strongly influenced by the composition but also affected by the oil content. Because paraffin is a byproduct of lubricant oils in the petrochemical industry, there is inherently a certain amount of oil that is difficult to remove completely. The determination of the oil content in paraffin is described by the ASTM method, which involves the oil extraction with methyl ethyl ketone (MEK) at a very low temperature (-32 degrees C). However, this method is slow and scarcely precise. In this work, we characterized the main components of industrial paraffin (de-oiled paraffin and extracted oil) by gas chromatography in combination with mass spectrometry (GC/MS) and nuclear magnetic resonance (NMR) spectroscopy. Also, we developed two methods for the determination of the oil content in paraffin. The first method measures total isoparaffin content by GC. The second method uses near-infrared (NIR) spectroscopy to quantify the content of MEK-removable oil. The results obtained with the NIR-based method were quite consistent with those of the official, extraction-based method. NIR spectroscopy therefore provides an effective alternative to the ASTM method with the added advantage of substantially greater expeditiousness and reproducibility.