Analysis of beeswax adulteration with paraffin using GC/MS, FTIR-ATR and Raman spectroscopy
It is generally known that beeswax is falsified, and adulterated waxes are increasingly appearing in markets.
Gas chromatography/mass spectrometry (GC/MS), Fourier transform infrared and Raman spectroscopy techniques were used to assess changes in the composition of n-alkanes, fatty acids, monoesters, methyl esters, hydroxy esters, and carboxylic acids caused by the adulteration of beeswax by paraffin addition.
Both the calibration (pure beeswax and paraffin) and commercial samples of wax were used to compare the efficiency of these methods. For this purpose, the ratio of palmitic acid methyl ester to octacosane was used in GC/MS.
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Using spectroscopic methods, the relative content of carbonyl groups was chosen as the assessment criterion, and quantitative calibration was based on the ratio of the stretching vibration of the C = O bonds and the deformation vibration of the aliphatic C–H bonds.
It was found that even a small addition of paraffin to beeswax caused more than a 50% reduction in the ratio, and 10% paraffin resulted in a 17-fold reduction in the ratio with respect to the pure beeswax sample.
Given that beeswax processing includes multiple heating and cooling, the influence of temperature and time on the chemical composition of the waxes was also investigated.
There was a trend towards a simultaneous decrease in carboxylic acid groups and an increase in hydroxy esters and palmitic acid methyl ester with increasing heating time.
However, the changes were small, so the heating process does not affect significantly the quality of beeswax.
Source: Taylor and Francis Online