Urea analysis for wines

Almy, John; Ough, C. S.

doi:10.1021/jf00088a031

Cited by 12 publications

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“…Recent methods in the literature for determination of urea in wines are based on enzymic analysis and monitoring of the pH change using two capillary glass electrodes capable of quantifying changes of pH of 0.001 units produced in the hydrolysis by urease [6]; on HPLC with a previous derivatisation reaction for facilitating separation [7,8] or on derivatisation with 1-phenyl-propan-1,2-dione 2-oxime in ethanol and photometric monitoring at 540 nm [9].…”

Section: Introductionmentioning

confidence: 99%

Method for monitoring urea and ammonia in wine and must by flow injection–pervaporation

Pérez-Juan¹,

Castro

2002

Analytica Chimica Acta

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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.

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Section: Introductionmentioning

confidence: 99%

Method for monitoring urea and ammonia in wine and must by flow injection–pervaporation

Pérez-Juan¹,

Castro

2002

Analytica Chimica Acta

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“…Optimization of the Method for the Determination of Urea in Sugar Cane Distilled Spirits. During optimization of the method described by Almy and Ough (5), some modifications (A-C) were undertaken in the preparation of the acid solution and also in the temperature and time necessary for the formation of the derivative. Analysis of the recoveries of urea using the different procedures at three spiking levels is indicated in Table 2.…”

Section: Resultsmentioning

confidence: 99%

“…However, urea is also formed as a consequence of yeast metabolism . Studies have indicated that arginine and citrulline are the main precursors , and that the yeast strain and fermentation temperatures can also cause increased urea accumulation in wines .…”

Section: Introductionmentioning

confidence: 99%

Spectrophotometric Determination of Urea in Sugar Cane Distilled Spirits

Labanca

Glória

2008

J. Agric. Food Chem.

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Urea is an important precursor in the formation of ethyl carbamate, a known carcinogen in alcoholic beverages. Ethyl carbamate has recently been detected at high concentrations in sugar cane distilled spirits, but little is known about the concentration of urea in these beverages. The objectives of this study were to validate methodology for the determination of urea in sugar cane distilled spirits, to determine the levels in 68 samples from different regions within the state of Minas Gerais, Brazil, and to examine the relationship between the concentrations of urea and ethyl carbamate. The method, based on the reaction of urea with 1-phenyl-1,2-propanodione-2-oxime and spectrophotometric quantification at 540 nm, provided linear response from 0.5 to 15.0 mg/L. No purification of the sample was required. The limits of detection and quantification were 0.1 and 0.5 mg/L, respectively. Urea was detected in 69% of the samples at levels varying from 0.50 to 5.10 mg/L. There was no significant difference on the levels of urea in samples from different regions of the state. No significant correlation between the levels of urea and ethyl carbamate was observed for the samples analyzed.

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“…We embarked on developing a simple and convenient nonradiolabel method to quantify urea accumulated in the stratum corneum. In this method (the "tape stripping-colorimetry (T-C) method"), the urea transferred to and retained in the stratum corneum is retrieved by tape stripping and is then measured by colorimetry (urease-glutamate dehydrogenase (GLDH)), [17][18][19][20][21][22] a measurement technique commonly used in blood tests. We here investigated the amount of formulation that must be applied for accurate measurement of the accumulated urea using the T-C method, used these conditions to show the relationship between the concentration of urea in the formulation (10 or 20%) and the quantity of urea accumulated in the stratum corneum, and assessed the effectiveness of the T-C method as a means of evaluating formulations.…”

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confidence: 99%

Deposits from Creams Containing 20% (w/w) Urea and Suppression of Crystallization (Part 2): Novel Analytical Methods of Urea Accumulated in the Stratum Corneum by Tape stripping and Colorimetry

Goto

Morita

Terada

2016

CHEMICAL & PHARMACEUTICAL BULLETIN

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The transfer of urea from a urea formulation to the stratum corneum varies with the formulation base and form, and impacts the formulation's therapeutic effect. Consequently, determining the amount of urea transferred is essential for developing efficient formulations. This study assessed a simple method for measuring the amount of urea accumulated in the stratum corneum. Conventional methods rely on labeling urea used in the formulation with radiocarbon ( 14 C) or other radioactive isotopes (RIs), retrieving the transferred urea from the stratum corneum by tape stripping, then quantitating the urea. The handling and use of RIs, however, is subject to legal regulation and can only be performed in sanctioned facilities, so methods employing RIs are neither simple nor convenient. We therefore developed a non-radiolabel method "tape stripping-colorimetry (T-C)" that combines tape stripping with colorimetry (urease-glutamate dehydrogenase (GLDH)) for the quantitative measurement of urea. Urea in the stratum corneum is collected by tape stripping and measured using urease-GLDH, which is commonly used to measure urea nitrogen in blood tests. The results indicate that accurate urea measurement by the T-C method requires the application of 1400 mg (on hairless rats) of a 20% urea solution on a 50 cm 2 (5 10 cm) area. Further, we determined the amount of urea accumulated in the stratum corneum using formulations with different urea concentrations, and the time course of urea accumulation from formulations differing in the rate of urea crystallization. We demonstrate that the T-C method is simple and convenient, with no need for 14 C or other RIs.

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Urea analysis for wines

Cited by 12 publications

References 0 publications

Method for monitoring urea and ammonia in wine and must by flow injection–pervaporation

Method for monitoring urea and ammonia in wine and must by flow injection–pervaporation

Spectrophotometric Determination of Urea in Sugar Cane Distilled Spirits

Deposits from Creams Containing 20% (w/w) Urea and Suppression of Crystallization (Part 2): Novel Analytical Methods of Urea Accumulated in the Stratum Corneum by Tape stripping and Colorimetry

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