An enzymic creatinine assay and a direct ammonia assay in coated thin films

Autor:	R W Becker, M W Sundberg, C T Goodhue, T W Esders, J Figueras
Rok vydání:	1983
Předmět:	Creatinine chemistry.chemical_compound Ammonia Chromatography chemistry Glutamate dehydrogenase Biochemistry (medical) Clinical Biochemistry Kinetics Semipermeable membrane Bromphenol Blue Colorimetry (chemical method) Dilution
Zdroj:	Clinical Chemistry. 29:645-649
ISSN:	1530-8561 0009-9147
DOI:	10.1093/clinchem/29.4.645
Popis:	We developed a thin-film enzymic assay for creatinine that makes use of creatinine iminohydrolase (EC 3.5.4.21) to convert creatinine to N-methylhydantoin and ammonia. The ammonia diffuses through a semipermeable layer and is quantitated by reaction with bromphenol blue. A paired analysis of the sample on a separate coating without the enzymic reaction measures endogenous ammonia and, for samples with normal concentrations of ammonia, allows accurate determination of serum creatinine to 150 mg/L without dilution. Results of this assay (y) compare well with those by a liquid-chromatographic comparison assay (x) by linear regression (slope = 0.935, intercept = 1.13 mg/L, r2 = 0.995). It is insensitive to many substances, such as ketones and keto acids, that interfere with conventional assays. Results of the ammonia assay (y) correlate well with those by a semi-automated enzymic assay (x) based on glutamate dehydrogenase (slope = 1.068, intercept = 17.3 mumol/L, r2 = 0.985).
Databáze:	OpenAIRE
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