Abstract: The present disclosure deals with the biochemistry of reagents useful in the detection of ammonia in liquid samples. Specifically, the present disclosure is directed to a technical improvement of an enzyme-based test for ammonia that can be used for analysis of plasma samples taken from patients in clinical settings, among other uses. In this regard, stability of a reagent containing NAD(P)H is improved, enhancing shelf life and results in the detection of ammonia. In an exemplary reagent ammonia released as a result of NAD(P)H decay is scavenged using an enzymatic reaction to convert the ammonia using GLDH, NAD(P)H and 2-oxoglutarate, thereby forming L-glutamate, NAD(P)+ and H2O in the NAD(P)H containing reagent.

Abstract: The subject matter of the invention is a stable mixture for the detection of alkaline phosphatase, wherein it contains the N-methylglucamine salt of o-cresolphthalein monophosphoric acid and N-methylglucamine as well as an analytical element for the detection of alkaline phosphatase with a matrix that carries this mixture. In addition the invention concerns a method for the determination of alkaline phosphatase using a salt of o-cresolphthalein monophosphoric acid, wherein the sample is brought into contact with a mixture according to the invention or an analytical element according to the invention and a change in color is observed in the presence of alkaline phosphatase.A subject matter of the invention is also a salt of o-cresolphthalein monophosphoric acid with N-methylglucamine as well as a process for producing such a salt.