Determination of encapsulated menthol flavour using thermal desorption gas chromatography

The analysis of menthol in encapsulated products is challenging due to the nature of the encapsulating matrices and the volatility of the analyte. Normal sampling/extraction procedures cannot be applied to the different types of menthol encapsulated products, due to variable extraction efficiencies of the analyte. This paper details the extraction and analysis of menthol flavour using a two stage thermal desorption GC process. This two stage thermal desorption system, using a Tenax TR packed cold trap, enables a narrow band of the extracted menthol to be focused onto the GC column. The method showed linearity in the range of 0.2-0.8 mg of menthol with a correlation coefficient greater than 0.999. Average instrumental precision of 3% RSD was determined and method precision was in the range of 2.1-9.4% RSD. This method was specific to menthol showing no interfering peaks. All the menthol was extracted in one extraction step. The specific analysis of menthol in encapsulated products allowed comparison of the efficiency of encapsulating processes, by comparing menthol loading values. RSD values for the different microparticles also indicate the relative homogeneity of the systems.