To characterise links between different illicit drugs chemical profiles, various distance or correlation measurements are available.Different comparison methods have been tested and a method based on a correlation coefficient using a square cosine function was chosen to compare heroin chemical profiles. Its functioning and graphical representation are described. An assessment of the number of false positives is calculated and lead to a negligible number.Moreover, it emerges from the studies that possible variations in impurity peak areas subject to possible degradations do not influence the C correlation value nor question the already established links. This solid, reliable and simple method appears therefore suitable for heroin samples comparison, links profiling and routine use.