MULTICOMMUTATION IN FLOW-ANALYSIS .3. SPECTROPHOTOMETRIC KINETIC DETERMINATION OF CREATININE IN URINE EXPLOITING A NOVEL ZONE SAMPLING APPROACH

Zone sampling performed on a single analytical channel and associated with the stopped-flow approach was proposed and applied to the spectro photometric kinetic determination of creatinine in urine based on Jaff e's reaction. The flow network comprised microcomputer controlled thre e-way solenoid valves. With multicommutation, the potentialities of zo ne sampling and stopped-now were expanded, and the design of the flow set up was simplified. Influence of the main related parameters such a s system configuration, reagent concentrations, temperature and timing were studied. The proposed system handled about 24 samples per hour. Baseline drift was not observed during extended operation periods (8 h ). Sample pretreatment was not required. Results were reproducible (R. S.D. <3%) and in agreement with those obtained in a batch procedure.