Abstract: Method employing gas chromatography for determining a measure of match between chromatographic data respective of a sample and reference data, the method includes the procedures of acquiring the chromatographic data, determining a plurality of parameters in a modeling function so as to substantially fit the modeling function to the chromatographic data, the modeling function defined as a sum of a linear combination of probability distribution functions, and estimating the measure of match according to a degree of fitness between the modeling function and the chromatographic data.