title: Automated measurement of urinary creatinine by multichannel kinetic spectrophotometry.
abstract: Urinary creatinine analysis is required for clinical diagnosis, especially for evaluation of renal function. Creatinine adjustment is also widely used to estimate 24-h excretion from spot samples. Few convenient validated approaches are available for in-house creatinine measurement for small- to medium-scale studies. Here we apply the Jáffe reaction to creatinine determination with zone fluidic multichannel kinetic spectrophotometry. Diluted urine sample and reagent, alkaline picric acid, were mixed by a computer-programmed dispenser and rapidly delivered to a four-channel detection cell. The absorbance change was monitored by a flow-through light-emitting diode-photodiode-based detector. Validation results against high-performance liquid chromatography-ultraviolet (HPLC-UV)/mass spectrometry (MS) are presented. Responses for 10-fold diluted samples were linear within clinically relevant ranges (0-250 mg/L after dilution). The system can analyze 70 samples per hour with a limit of detection of 0.76 mg/L. The relative standard deviation was 1.29% at 100 mg/L creatinine (n=225). Correlation with the HPLC (UV quantitation/MS confirmation) system was excellent (linear, r2=0.9906). The developed system allows rapid, simple, cost-effective, and robust creatinine analysis and is suitable for the analysis of large numbers of urine samples.
authors.affiliation: Department of Chemistry and Biochemistry, University of Texas at Arlington, 700 Planetarium Place, Arlington, TX 76019-0065, USA.
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Ohira
authors.forename: Andrea B
authors.initials: AB
authors.lastname: Kirk
authors.forename: Purnendu K
authors.initials: PK
authors.lastname: Dasgupta
mesh_terms: D002851:Chromatography, High Pressure Liquid; D003404:Creatinine / Q000737:chemistry / Q000652:urine*; D007700:Kinetics; D013053:Spectrophotometry / Q000191:economics / Q000295:instrumentation / Q000379:methods*
chemical_list: D003404:Creatinine