Submitted to: Journal of Liquid Chromatography and Related Technologies
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/5/2018
Publication Date: 11/26/2018
Citation: Moreau, R.A., Harron, A.F., Hoyt, J.L., Powell, M.J., Hums, M.E. 2018. Analysis of wax esters in seven commercial waxes using C30 reverse phase HPLC. Journal of Liquid Chromatography and Related Technologies. 41(10):604-611. https://doi.org/10.1080/10826076.2018.1485036.
Interpretive Summary: Commercial waxes are obtained from plant (carnauba, candelilla, rice bran, and sunflower waxes), animal (beeswax) and petroleum (paraffin wax) sources. Until now, almost all of the analyses of commercial waxes have been conducted using gas chromatography, but gas chromatography has issues due to the breakdown of some wax components at high temperatures. We developed a new method employing high performance liquid chromatography (HPLC) to analyze commercial waxes. It is the first successful HPLC method for wax analysis. It uses a C30 reverse phase column, an evaporative light scattering detector for quantification and an atmospheric pressure mass spectrometer for chemical identification. The new method was found to be useful for the analysis of jojoba oil (a wax), carnauba wax, candelilla wax, rice bran wax, sunflower wax, beeswax, and paraffin waxes.
Technical Abstract: Commercial waxes are difficult to analyze due to their limited solubility in most organic solvents. Recently, our laboratory published a new reverse phase HPLC-MS method using a C30 column, a gradient of methanol and chloroform, an evaporative light-scattering detector (ELSD), and atmospheric pressure chemical ionization mass spectrometry (APCI-MS) to analyze sorghum wax and carnauba wax. In the current study, the published HPLC method was modified by reducing it to 60 minutes and it was used to evaluate its usefulness for the analysis of other commercial waxes (candelilla, rice bran, sunflower, beeswax and paraffin waxes). The ELSD appeared to detect all types of wax components, whereas the APCI-MS was most useful for the identification of wax esters and less useful for hydrocarbons. Size exclusion HPLC was also used to compare the same commercial waxes with detection by both a charged aerosol detector and ultra violet (UV) spectrometry at 254 nm. These novel methods provide new insights into the chemical structures and physical properties of commercial waxes.