Validation of qualitative analytical methods

Trullols, Esther; Ruisánchez, Itziar; Rius, F. Xavier

doi:10.1016/s0165-9936(04)00201-8

Cited by 184 publications

(109 citation statements)

References 18 publications

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“…In general, limits of percentages of 5% for both false positive and false negative are recommended for the validation of qualitative methods. 33 But in the case of seized drug analysis, in which the complexity of the matrices makes qualitative tests especially prone to produce false results, 21 higher limits are considered acceptable. These models constitute a simple, rapid and non-destructive tool, of great importance to speed criminal investigations.…”

Section: Resultsmentioning

confidence: 99%

Analysis of seized cocaine samples by using chemometric methods and FTIR spectroscopy

Rodrigues¹,

Cardoso²,

Andrade³

et al. 2013

J. Braz. Chem. Soc.

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O objetivo deste trabalho foi desenvolver uma metodologia quimiométrica para descrever o perfil químico de amostras de cocaína apreendidas no estado de Minas Gerais (Brasil). A identificação de adulterantes e a quantificação do teor de cocaína foram feitas por cromatografia gasosa acoplada à espectrometria de massa (GC-MS). Espectros de 91 amostras foram obtidos por espectroscopia no infravermelho usando refletância total atenuada (ATR-FTIR), e utilizados na construção de um modelo de análise de componentes principais (PCA). A primeira componente principal (PC1) discriminou as amostras de maior pureza das mais diluídas/adulteradas, nas quais foram identificadas lidocaína, cafeína e benzocaína. PC2 discriminou a forma química da cocaína, cloridrato ou base. Além disso, dois modelos supervisionados discriminantes (mínimos quadrados parciais para análise discriminante, PLS-DA) foram desenvolvidos para classificar as amostras em função de sua diluição (abaixo e acima de 15% m/m) e de sua forma química, apresentando taxas de acerto que variaram entre 83 e 97%. Os modelos de classificação constituem uma ferramenta simples, rápida e não destrutiva, de grande valor para peritos forenses e investigadores criminais.The aim of this article was to develop a chemometric methodology for determining the chemical profile of cocaine samples seized in Minas Gerais State, Brazil. The adulterant detection and the cocaine determination were performed by gas chromatography-mass spectrometry (GC-MS). Spectra of 91 samples were obtained by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and used to build an exploratory principal component analysis (PCA) model. The first principal component (PC1) discriminated samples of more purity from the more diluted/adulterated ones, which were characterized by the presence of lidocaine, caffeine and benzocaine. PC2 discriminated the two chemical forms of cocaine, hydrochloride and base. In addition, two supervised discriminant partial least-squares models (partial least-squares discriminant analysis, PLS-DA) were developed for classifying the samples according to dilution (above and below 15% m/m) and chemical form, with a rate of success that varied between 83 and 97%. The classification models constitute a simple, rapid and non-destructive tool, of great value for both forensic experts and criminal investigators. Keywords: illicit drugs, MID infrared, principal component analysis, cocaine, chemometrics IntroductionCocaine is an alkaloid extracted from plants of the genera Erythroxylum (E. novagranatense and E. coca). United Nations Office on Drugs and Crime (UNODC) considers cocaine, after heroin, the second most problematic drug worldwide in terms of negative health consequences and probably the most problematic drug in terms of trafficking-related violence. Estimates suggest that 440 t of pure cocaine were consumed in the world in 2009, which would be in line with a total production estimate of 1,111 t, wholesale purity-adjusted seizures Analysis of Seized Cocain...

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Section: Resultsmentioning

confidence: 99%

Analysis of seized cocaine samples by using chemometric methods and FTIR spectroscopy

Rodrigues¹,

Cardoso²,

Andrade³

et al. 2013

J. Braz. Chem. Soc.

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“…It is considered as a fundamental notion and can be described as a representation of the core component in the case of the use and acquisition of goods or services of any type (Kolman, 1971;Borys, 1991;Trullols-Soler, 2006;Nazarov, Krushnyak, 2006). As a result of this thinking, a scientific discipline called qualitology was formed, which is focused on quality and its modelling (Martínez, 2008).…”

Section: Description Of the Proceduresmentioning

confidence: 99%

The quality of pedestrian space in the city: a case study of Olsztyn

Cieślak

Szuniewicz

2015

Bulletin of Geography. Socio-Economic Series

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Abstract. The system of pedestrian urban space is the primary source of information on the state of the space. Walking around a city, we are perceptually building in our mind its physiognomic silhouette, which becomes the basis for evaluating the attractiveness of a city. Unfortunately, pedestrian traffic is rarely the subject of careful planning and design. Usually it regulates itself or is a side-effect of building an extensive system of road communication. On the other hand, concepts of shaping this system as a primary one appear more and more often, and pedestrian space is seen as high priority public space. The purpose of the article was to evaluate qualitative evaluation methods determining the current state of pedestrian pathways in the town Giżycko. Valuing quality, as a part of the science called qualimetrics, refers to determining the quality of objects which are the product of human activities, designed to meet the needs of human beings. At the root, it is a science relating to the determination of the quality of market items, supporting the production management process. As space, particularly urbanized, is created by people to satisfy their needs, it was concluded that quality valuation methods may also be useful to assess the quality of space. The article focuses on the quality of pedestrian routes that are essential to the central part of Giżycko. For these routes, the current state of the features identified as key for their quality was investigated, and quality classes of the routes were determined by analysis. The procedure can be a tool supporting the planning and implementation of modernization and renovation works for the area of pedestrian communication, and thus the image of the city.

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“…Neste contexto, o uso da análise screening como processo preliminar de análise, mostrando a necessidade ou não de uma análise pelos mé-todos de referência, para classificação e verificação da falsificação em vinhos torna-se um objetivo bastante relevante, pois diminui os custos da indústria com análises desnecessárias. [10][11][12][13][14] Em termos de fornecimento de resultados rápidos, a análise screening torna-se ainda mais interessante se realizada usando analisadores automáticos.…”

Section: Introductionunclassified

Análise screening de vinhos empregando um analisador fluxo-batelada, espectroscopia UV-VIS e quimiometria

et al. 2010

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Recebido em 12/3/09; aceito em 13/8/09; publicado na web em 8/1/10 SCREENING ANALYSIS OF WINES USING FLOW-BATCH ANALYZER, UV-VIS SPECTROSCOPY AND CHEMOMETRICS. A simple, robust, versatile, high analytical frequency method was proposed to check if a sample of wine is within the range of standards set by the manufacturer, using the UV-VIS spectroscopy, multivariate analysis and a flow-batch analyzer. Two hundred and fifty-two samples of wines were analyzed. The results from the application of Hierachical Cluster Analysis (HCA) to the matrix of the data involving all samples show the formation of fifteen types of wine. A Soft Independent Modelling of Class Analogy (SIMCA) model was constructed and used to classify the samples of the overall forecast. As a result, it is observed that the prediction was performed with a success rate of 99.2% for a confidence level of 95%. This shows that the proposed methodology can be used as an effective tool for classifying of samples of wines.Keywords: quality control of wines; flow-batch analyzer; chemometrics. INTRODUÇÃOO vinho é uma bebida simples, resultante da conversão gradual dos açúcares presentes no mosto de uvas frescas em álcool, CO 2 e energia por intermédio do levedo.1 Desta forma, vinhos de má qualidade são facilmente elaborados, bem como bastante propícios a falsificações e/ou adulterações. As falsificações e/ou adulterações de alimentos constituem crime contra a saúde pública, na medida em que são comercializados produtos ilegais, sem controle e sem fiscalização, que podem prejudicar a saúde da população, além de lesar o consumidor que paga caro por um produto de qualidade e de sonegar impostos aos órgãos governamentais. Muitos são os relatos de casos de falsificação e/ou adulterações de vinhos e, preocupadas com este problema, as indústrias produtoras tentam, a todo custo, tomar medidas que amenizem esta situação.Existe uma vasta variedade de vinhos e a forma mais comum para classificá-los corresponde ao seu aspecto visual e pigmentação característica. Porém, existem outras classificações que têm a ver com o processo de vinificação ou, ainda, quanto ao teor de açúcar. A classificação e a caracterização de vinhos vêm sendo realizadas através da utilização de alguns parâmetros como teor alcoólico, pH, acidez fixa e volátil, teor de cinzas etc.2 Para isso têm sido utilizados métodos espectroscópicos de massa, 3 de emissão óptica, 4 de espectroscopia NIR 5 e de absorção atômica em chama. 6 No entanto, a técnica analítica padrão de referência utilizada para a verificação da autenticidade de vinhos no Brasil é a cromatografia.7 Tal técnica apresenta um custo elevado de seus instrumentos e de manutenção constante, bem como requer a preparação de reagentes e soluções padrão com produção de resíduos prejudiciais à saúde e/ou ao meio ambiente, além de apresentar uma baixa frequência analítica. Uma boa alternativa para superar estes inconvenientes é o desenvolvimento de métodos analíticos que combinam o uso da espectrometria de absorção molecular UV-VIS, analisadores automá...

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Validation of qualitative analytical methods

Cited by 184 publications

References 18 publications

Analysis of seized cocaine samples by using chemometric methods and FTIR spectroscopy

Analysis of seized cocaine samples by using chemometric methods and FTIR spectroscopy

The quality of pedestrian space in the city: a case study of Olsztyn

Análise screening de vinhos empregando um analisador fluxo-batelada, espectroscopia UV-VIS e quimiometria

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