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

作者：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 Julian

来源：Analytical and Bioanalytical Chemistry, 2010, 398(3): 1525-1533.

DOI：10.1007/s00216-010-4052-6

• Urea
• Milk
• Low temperature co-fired ceramics
• Berthelot's reaction
• Multicommutation
• Mini-photometer

A 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 1.0x10(-4) to 5.0x10(-3) mol L(-1) with a limit of detection of 8.0x10(-6) mol L(-1). The relative standard deviation (RSD) for a 2.0x10(-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.

• 出版日期2010-10-10