. Prof. Luiz Freire, s/n, 50740-550 Recife -PE, BrasilRecebido em 14/2/07; aceito em 19/7/07; publicado na web em 19/12/07 MULTIVARIATE ANALYSIS OF PHYSICO-CHEMICAL PARAMETERS IN SAMPLES OF RED WINES SOLD IN THEMETROPOLITAN AREA OF RECIFE. The Brazilian legislation requires analysis of certain parameters to classify a wine and allow its commercialization. Some physico-chemical and some color parameters were determined in this work in samples of different red wines sold in the metropolitan area of Recife. Multivariate analysis comprising principal component analysis and hierarchical cluster analysis was employed to distinguish the analyzed wines. The results for pH, chloride concentration, color parameters and ammonium content were the most important variables for sample classification. It was also possible to classify the wines as soft or dry wines and amongst the soft wines we could determine two out of four winegrowing producers.Keywords: red wine; physico-chemical methods; chemometrics. INTRODUÇÃOO vinho é, por definição, a bebida obtida pela fermentação alcoólica do mosto simples de uva sã, fresca e madura. O mosto simples de uva é o produto obtido pelo esmagamento ou prensagem da uva, com a presença ou não de suas partes sólidas. Assim, é vedada a denominação de vinho para produtos obtidos de quaisquer outras matérias-primas 1 .Sendo o vinho proveniente de um processo natural, que é a fermentação alcoólica, ele é elaborado ao invés de fabricado e possui composição química e sensorial distintas, de acordo com o solo, o clima e a água da região vinícola que origina as uvas.Além dos fatores geográficos e tecnológicos, existem outros que também influenciam a qualidade de um bom vinho, tais como a garrafa na qual será armazenado (cor e forma), a rolha, a temperatura e a posição de estoque dos vinhos, as taças, a temperatura e a forma correta de serví-lo e, até mesmo, a combinação com as comidas. Tais fatores podem ser denominados como enológicos. Outros que merecem destaque especial são aqueles que os enólogos utilizam para definir o vinho como um alimento ao invés de uma simples bebida alcoólica: as vitaminas, os minerais, os aminoácidos, os carboidratos, ou seja, a sua composição química 2,3 .No Brasil, o Ministério da Agricultura é o órgão responsável em criar e fiscalizar leis e normas que definem, regularizam e controlam a elaboração e circulação dos vinhos. A lei 10.970, de 12 de novembro de 2004, dispõe sobre produção, circulação e comercialização de vinhos 4 e a portaria 229, de 25 de outubro de 1988, decreta os padrões de identidade e qualidade do vinho 5 . Nesta portaria, são indicados, além das definições básicas dos diferentes tipos de vinho, os teores máximos e mínimos para alguns constituintes da composição do vinho.

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This article describes a multicommuted flow procedure for photometric determination of the polyphenol content in wines and teas, exploiting the formation of unstable intermediate products, by the reaction of sodium hypochloride with gallic acid. Because the lifetime of the formed compound is very short, a special flow cell was designed in order to enable mixing of sample and reagent solution within the flow cell, thus allowing signal monitoring, while compound formation proceeded. The flow system manifold comprised three solenoid mini-pumps to propel sample, reagent solution, and carrier fluid. The photometer consisted of a photodiode and a light emitting diode (LED) with maximum emission at 490 nm. Under the selected operational conditions, useful features including a linear response ranging from 62 to 1000 mg L −1 gallic acid solution (R = 0.9987), a detection limit of 21 mg L −1 gallic acid, a sampling rate of 120 determinations per hour, a relative standard deviation of 1.9 % (n = 20) for a typical solution containing 400 mg L −1 gallic acid, and a waste generation of 1.0 mL per determination were also achieved. Medium recovery values of 96.2 ± 10.4 and 101.9 ± 7.3 % for wines and teas, respectively, were achieved.

Contaminated water is one of the main public health risks. One way to assess its quality is by quantifying nitrate through ultraviolet (UV) spectrophotometry. In this work, the performance of the UV spectrophotometric method for nitrate ion determination in water was studied, with linearity, precision, accuracy, limit of detection (LOD), limit of quantification (LOQ) and robustness being verified. In the working range studied (5.0-25.0 mgN·L-1), all validation parameters are in accordance with the acceptance criteria established by INMETRO. In linearity, the value of r (0.999) was higher than the criterion (0.995). In the study of precision and accuracy, the coefficients of variation for repeatability and intra-laboratory reproducibility were 1.79 and 2.34%, and 1.44 and 2.52%, respectively (<5%). The value of the relative error (15.8 and 8.1%) was also lower than the criterion (≤ 20%). The LOD and LOQ obtained were 0.56 and 1.70 mgN·L-1, respectively. In the evaluation of the robustness no factor had a significant effect on the final result. Analyzing real samples, the percentages of recovery were between 88.5 and 103.6%, according to the established criteria (80-110%). In this way, it can be said that the method presents reliability to the intended purpose.

The minimum parameters of identity and quality of butters in Brazil are governed by the Ministry of Agriculture, Livestock and Supply. From them it is possible to carry out the performance verification of the methodologies to guarantee the results reliability. Thus, the objective of this study was to analyze the performance of the method of determination of NaCl in butter, based on ISO 1738:2004, evaluating accuracy, precision and the limit of quantification (LOQ). The precision was obtained since the coefficients of variation found in the tests were lower than the Horwitz value. The accuracy was approved as a consequence of the confirmation of the proficiency having as provider the FAPAS. The LOQ of 0.41g of NaCl/100g of butter was established by evaluating the accuracy and the recovery in a NaCl content determination test, using a solution prepared with Certified Reference Material. To assure quality, the uncertainty associated with the NaCl measurement was also estimated, through the evaluation of the possible sources of uncertainty, among which were: weighing, analyzer, glassware and the reagent purity, with a measurement uncertainty of 0.03g NaCl/100g of sample. Finally, it was verified the conformity of the NaCl content in commercial samples according to the Brazilian legislation.