LC-ELSD for single-step quantitative analysis of aliphatic compounds in natural waxes

Natural waxes occur as by-products during oil refining and show potential for food applications in oleogels or for cosmetic applications. Waxes are high melting substances mainly composed of long-chained wax esters (WE), fatty alcohols (FaOH), fatty acids (FA) and hydrocarbons (HC). Waxes of different origin vary greatly in both proportions of the individual fractions and their respective molecular composition.

Current approaches to characterize wax compositions either lack sensitivity or require excessive efforts like hydrolysis of WE and methylation of FA followed by MSD.

The LC-ELSD method presented here is a single-step determination of the aliphatic compounds in natural waxes. The detectable range of total carbon number spans from 16 to more than 56 carbon atoms. If present, more than 30 different substances of a single wax can be quantified. This marks a significant extension compared to existing LC methods.

In this contribution, the method is described in detail and its verification against literature data is discussed. For natural waxes considered – beeswax (BWX), sunflower (SFX), rice bran, sugarcane, candelilla and carnauba wax – obtained data is in good agreement with literature data. Furthermore, application of the method to determine batch-to-batch variations and their propagation into oleogel properties will be shown. This illustrates not only the strength of the proposed method, but also its necessity for future quality control considering wax composition.

To successfully design natural wax applications, their properties need to be tailorable. Mixing of different waxes or modification methods such as partial hydrolysis of the WE change the specific composition as oleogelators. Here again, the link between composition and oleogel physical properties is made for hydrolyzed SFX and BWX.

All results presented in this contribution show the potential of the new method to deliver a systematic composition database, enabling to unravel the relation between wax composition and application performance.