02032naa a2200265 a 450000100080000000500110000800800410001902400350006010000180009524501200011326000090023352012310024265000090147365000090148265300270149165300380151870000230155670000220157970000260160170000170162770000240164470000140166870000150168277300690169718633112023-06-30       2010    bl uuuu     u00u1 u    #d7 a10.1007/s00216-010-4052-62DOI1 aSUAREZ, W. T.  aA compact miniaturized continuous flow system for the determination of urea content in milk.h[electronic resource]  c2010  aA multicommutation-based flow system with photometric detection was developed, employing an analytical microsystem constructed with low temperature cofired ceramics (LTCC) technology, a solid-phase reactor containing particles of Canavalia ensiformis DC (urease source) immobilized with glutaraldehyde, and a miniphotometer coupled directly to the microsystem which monolithically integrates a continuous flow cell. The determination of urea in milk was based on the hydrolysis of urea in the solid-phase reactor and the ammonium ions produced were monitored using the Berthelot reaction. The analytical curve was linear in the urea concentration range from 1.0×10 -4 to 5.0×10 -3 mol L -1 with a limit of detection of 8.0×10 -6 mol L -1. The relative standard deviation (RSD) for a 2.0×10 -3 mol L -1 urea solution was lower than 0.4% (n=10) and the sample throughput was 13 h?1. To check the reproducibility of the flow system, calibration curves were obtained with freshly prepared solutions on different days and the RSD obtained was 4.7% (n=6). Accuracy was assessed by comparing the results of the proposed method with those from the official procedure and the data are in close agreement, at a 95% confidence level.  amilk  aurea  aBerthelot’s reaction  aLow temperature co-fired ceramics1 aPESSOA NETO, O. D.1 aSANTOS, V. B. dos1 aNOGUEIRA, A. R. de A.1 aFARIA, R. C.1 aFATIBELLO FILHO, O.1 aPUYOL, M.1 aALONSO, J.  tAnalytical & Bioanalytical Chemistrygn. 398, p. 1525-1533, 2010