Comment by hilbert42

Have you ever seen that triangular chart comparing concentrations, impurities , etc? It's generally presented on log scales and very effectively demonstrates the often enormous number of trace-level compounds in otherwise substances deemed pure. It's the absolute pinnacle when it comes to teaching chem students about purity.

No doubt you're correct but it only takes one compound in trace amounts whose odor can be detected in parts per million to throw out a seemingly identical comparison done with spectroscopy.

Right, calibration is everything but sometimes that's damn hard to achieve. Also, here we're dealing with natural substances (at least some are like cola leaves). It's not hard to imagine there'd be thousands of organic molecules involved albeit most of them in minute amounts.