A compact miniaturized continuous flow system for the determination of urea content in milk

Suarez, Willian Toito; Pessoa-Neto, Osmundo Dantas; Dos Santos, Vagner Bezerra; De Araujo Nogueira, Ana Rita; Faria, Ronaldo Censi; Fatibello-Filho, Orlando; Puyol, Mar; Alonso, Julián
October 2010
Analytical & Bioanalytical Chemistry;Oct2010, Vol. 398 Issue 3, p1525
Academic Journal
multicommutation-based flow system with photometric detection was developed, employing an analytical microsystem constructed with low temperature co-fired ceramics (LTCC) technology, a solid-phase reactor containing particles of Canavalia ensiformis DC (urease source) immobilized with glutaraldehyde, and a mini-photometer 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 to 5.0 × 10 mol L with a limit of detection of 8.0 × 10 mol L. The relative standard deviation (RSD) for a 2.0 × 10 mol L urea solution was lower than 0.4% ( n = 10) and the sample throughput was 13 h. 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. [Figure not available: see fulltext.]


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