Specific method for serum creatinine determination based on ion exchange chromatography and an automated alkaline picrate reaction -- a proposed reference method.
A proposed reference method for serum creatinine has been developed under the auspices of the Committee on Reference Methods and Reference Materials of the Canadian Society of Clinical Chemists. A serum ultrafiltrate at pH 2.0 is applied through a closed sample loop injection system to a short column containing cationic resin of high resolving power. Elution with sodium citrate buffer by means of minipump at constant rate passes the eluate into alkaline picrate reagents in a continuous flow system (Technicon AAIII pump, AAII colorimeter 50 mm x 1.5 mm flow cell, narrow band width filter). The colour reaction peak is monitored visually to verify specificity and the area is calculated electronically. Specificity has been demonstrated by use of Jaffé-reactive substances such as glucose, sodium acetoacetate, L-ascorbic acid, pyruvic acid, L-dopa and glycocyamidine and also by use of an alternate colour reaction, sodium 3,5-dinitrobenzoate in place of alkaline picrate in the analysis of serum pools. Routine methods in common use, i.e., manual and automated alkaline picrate procedures, demonstrated a statistically significant high bias in interlaboratory studies in which this procedure was used for reference.
D001322:Autoanalysis; D002852:Chromatography, Ion Exchange / Q000295:instrumentation; D003404:Creatinine / Q000097:blood* / Q000592:standards; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008722:Methods; D009579:Nitrobenzoates; D010851:Picrates; D012015:Reference Standards
D009579:Nitrobenzoates; D010851:Picrates; D003404:Creatinine