Gas chromatography–mass spectrometry separates a complex natural material into its constituents and proposes an identity for each. For a natural absolute it is the most useful single document after the Certificate of Analysis — provided it is read correctly.

The columns

• —Retention time (RT): when a compound leaves the column. It helps compare two reports run on the same method.
• —Compound name and CAS number: the proposed identity, from a reference spectral library.
• —Match score: how closely the measured spectrum resembles the library spectrum. A high score is a strong indication, not a certainty.
• —Probability: the software’s confidence among candidate matches.

Qualitative is not quantitative

A library identification tells you what is present. It does not, on its own, tell you how much. A report listing identified compounds and match scores is a qualitative document; relative area percentages are needed to compare profiles batch to batch.

Our current GC-MS report on Champaca Absolute Oil is a qualitative identification. It includes phenylethyl alcohol, methyl benzoate, methyl anthranilate, α-ionone, benzyl benzoate and benzyl alcohol among the constituents identified.

Three questions to ask

• —Does the batch number on the report match the batch number on the vial and the certificate?
• —Was the analysis run on the same batch you are evaluating, and when?
• —Can the supplier show you where — and on which day — that batch was harvested?

A report is only as good as the batch number it carries.