Open Peptide Index
Physical

Headspace oxygen

Oxygen in the gas space above the product. Correlates with sulfoxide content and is essentially never measured.

Related terms

Oxidation
Addition of oxygen. Methionine to sulfoxide (+15.995) then sulfone (+31.990); tryptophan to oxindole and beyond; cysteine to sulfonic acid.
Closure integrity
Whether the stopper and crimp maintain the container's seal and vacuum. A failure lets in moisture and oxygen.

Where this term appears

The glossary exists to make record pages readable without a chemistry degree. Every technical term on a report resolves here.