Gonzalez-Rodriguez, Jose and Perez Juan, Pedro and Luque de castro, Maria Dolores (2002) Method for monitoring urea and ammonia in wine and must by flow injection-pervaporation. Analytica Chimica Acta, 471 . pp. 105-111. ISSN 0003-2670

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Abstract

An easy to automate flow-injection-pervaporation method for monitoring urea and ammonia in must and wine was developed. The method is based on separation of the ammonia from the sample matrix by pervaporation followed by its reaction with salicylate, hypochlorite and nitroprusside to form a diazonium salt with maximum absorption at 647 nm. Conversion of urea into ammonia catalysed by urease was mandatory before pervaporation. After optimisation by either the univariate or multivariate approaches as required, the linear range was established (between 0 and 25 mg l-1) for both analytes. Then, the assessment of the proposed method versus a reference one for urea and ammonia was studied in terms of repeatability (0.52 mg l-1 and 0.43 mg l-1, respectively), reproducibility (1.34 mg l-1 and 1.21 mg l-1, respectively), detection and quantification limits (LOD=0.9 and 0.6 mg l-1, LQ=1.02 and 0.67 mg l-1, respectively) and traceability. The sample throughput was 16 samples h-1. The method can be applied to the monitoring of the target analytes in must and young wine in order to control their contents, preventing formation of ethyl carbamate.

Item Type:	Article
Additional Information:	An easy to automate flow-injection-pervaporation method for monitoring urea and ammonia in must and wine was developed. The method is based on separation of the ammonia from the sample matrix by pervaporation followed by its reaction with salicylate, hypochlorite and nitroprusside to form a diazonium salt with maximum absorption at 647 nm. Conversion of urea into ammonia catalysed by urease was mandatory before pervaporation. After optimisation by either the univariate or multivariate approaches as required, the linear range was established (between 0 and 25 mg l-1) for both analytes. Then, the assessment of the proposed method versus a reference one for urea and ammonia was studied in terms of repeatability (0.52 mg l-1 and 0.43 mg l-1, respectively), reproducibility (1.34 mg l-1 and 1.21 mg l-1, respectively), detection and quantification limits (LOD=0.9 and 0.6 mg l-1, LQ=1.02 and 0.67 mg l-1, respectively) and traceability. The sample throughput was 16 samples h-1. The method can be applied to the monitoring of the target analytes in must and young wine in order to control their contents, preventing formation of ethyl carbamate.
Keywords:	wine, must, pervaporation, flow injection, spectrophotometry, urea, ammonia, chemometry, experimental design, ethyl carbamate, derivatisation, validation method
Subjects:	F Physical Sciences > F112 Colour Chemistry F Physical Sciences > F110 Applied Chemistry F Physical Sciences > F190 Chemistry not elsewhere classified F Physical Sciences > F100 Chemistry F Physical Sciences > F180 Analytical Chemistry
Divisions:	College of Sciences > Faculty of Science > School of Life Sciences
Depositing User:	Jose Gonzalez-Rodriguez
Date Deposited:	08 Jan 2010 11:01
Last Modified:	13 Mar 2013 08:34
URI:	http://eprints.lincoln.ac.uk/id/eprint/2114

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