Measures the concentration of soluble sulfides and soluble carbonates The Garrett Gas Train (GGT) measures the concentration of sulfides or carbonates in drilling fluids and drilling fluid filtrates. This measurement gives a quantitative indication of the rate and amount of intrusion of hydrogen sulfide or carbon dioxide from the formation in the drilling fluid.

The Methylene Blue Test determines the amount of reactive solids in a fluid sample, based on the cation exchange capacity of the solids.