Reading A Glycerine Certificate Of Analysis
Purity at 99.7% minimum is the headline figure. Colour, ash, chlorides and MONG are the ones that decide whether the drum passes your incoming check.
Purity is the figure everyone reads first. Refined glycerine is offered at 99.7% minimum, and a certificate that says so has answered the easiest question on the sheet.
The rest of the sheet is what decides whether the drum passes your incoming check. Colour, reported on the APHA scale, tells you what the material will do to a finished product that is meant to be water-white. Ash and chlorides point to residues from the refining stage. MONG — matter organic non-glycerol — is the catch-all for everything organic that is not glycerine, and it is the line that most often explains an otherwise puzzling batch.
Read the specification limits beside the results, not the results alone. A number that sits inside a wide limit is not the same as a number that sits inside your limit, and the two only have to agree if your purchase specification said so in the first place.
Where the material is offered against a pharmacopoeia monograph, the certificate should name which one. That is a separate question from purity, and it is covered in the note on pharmacopoeia grades.
