A new chromogenic amylase method compared with two established methods.

We tested a new amylase reagent involving chromogenic substrates (Pantrak, Calbiochem-Behring) for precision, dynamic range, and susceptibility to potential interferences. Two p-nitrophenyl-alpha-maltaosides are used as substrates, which amylase cleaves to shorter-chain p-nitrophenyl maltaosides, the latter then yielding p-nitrophenol from the activity of alpha-glucosidase. A series of 100 specimens were tested by Pantrak and two established methodologies. In both cases, correlation was excellent. Precision was good for all methods; CVs for Pantrak were 3.0 to 4.5%. The dynamic range of Pantrak extended to 800 U/L. Above-normal quantities of triglyceride, hemoglobin, or bilirubin did not cause spurious results, but anticoagulants that bind divalent cations should not be used. The Pantrak method has desirable analytical features and is easy to use.