Glossary

Terms beginning with G

8 of 238 glossary terms.

Gradient: Programmed change in mobile-phase composition during a run. Gradient duration determines resolving power and is therefore part of the result, not metadata.
Gradient slope: Percentage points of organic solvent per minute. Lower slope, better resolution, longer run.
Guard column: A short disposable column before the analytical column, protecting it from particulates and strongly retained matrix. Shifts retention slightly and must be accounted for.
Ghost peak: A peak arising from material retained on the column from a previous injection and released by a later gradient. Detected by a blank injection.
Gravimetric fill check: Weighing a vial before and after removal of contents to determine the actual fill. The only direct measurement of label-claim compliance.
GC headspace: Gas chromatography of the vapour above a heated sealed sample. The standard technique for residual solvents.
Gel-clot: A limit-test LAL format: a firm gel forms or it does not. Gives a pass or fail against a stated sensitivity, never a number.
Gradient normalisation: Converting a retention time measured on one gradient duration to the index reference scale, so retentions from different laboratories can be compared.