Fast GC analysis of major volatile compounds in distilled alcoholic beverages: Optimisation of injection and chromatographic conditions

The principal secondary flavour compounds in distilled spirits can be successfully quantified by split injection to a 0.15 mm internal diameter (I.D.) capillary column. Initial conditions for split ratio, gas velocity, initial oven temperature and oven ramp rate are given by method translation from a similar method on a standard 0.25 mm internal diameter column with the same phase. These parameters were then investigated in an experimental design comprising a series of experiments in which the responses were the resolution of two critical peak pairs, the analysis time and the limit of quantification (LOQ) of the eight major compounds. The LOQ is the concentration corresponding to a signal 10 times greater than the noise. The experiments were replicated at two different concentration levels, which encompassed the natural levels of the compounds of interest found in distilled spirits. From the chemometric evaluation of these data, a validated model was constructed, which allowed the prediction of conditions for optimum chromatographic analysis. Three additional concentration levels were then added to the model to establish linearity, repeatability and sensitivity. Modern gas chromatographic hardware allows the use of these narrow-bore capillary columns for routine use without operational difficulties. Major advantages are a substantial decrease in analysis time allowing high throughput processing of samples.