Homogeneity and stability of reference materials

Linsinger, Thomas P. J.; Pauwels, J.; Veen, Adriaan M. H. van der; Schimmel, Heinz; Lamberty, A.

doi:10.1007/s007690000261

Cited by 229 publications

(118 citation statements)

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“…From the data in Table 4 in principle an uncertainty contribution for inhomogeneity can be calculated, following common approaches (eqn. 1, [5]). The uncertainty contributions u bb resulting from eqn.…”

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confidence: 99%

Final report of the key comparison CCQM-K72: Purity of zinc with respect to six defined metallic analytes

Vogl¹,

Kipphardt²,

Torres³

et al. 2014

Metrologia

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/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions? Contact the NRC Publications Archive team atPublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCFor the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://doi.org/10.1088/0026-1394/51/1A/08008 Metrologia, 51, 1A, 2014-01-01 CCQM-K72 Purity of Zinc with respect to six defined metallic analytes MotivationHigh purity elements can serve as a realisation of the SI unit amount of substance for the specific element. Solutions prepared from high purity metals by applying gravimetric preparation and the concept of molar mass are used as 'calibration' solutions in many fields of analytical chemistry and provide the metrological basis in elemental analysis. Since ideal purity does not exist for real materials, the actual purity of the high purity material must be known with a specified uncertainty. Such purity data, however, are only accessible via measurements, which are limited by their measurement uncertainty. Aiming at uncertainties around 10 -4relative on the purity statement in almost all cases a direct measurement of the element in itself is not applicable, because the available methods are not sufficiently selective and/or accurate. Therefore the indirect approach is followed in order to achieve uncertainties at this level. In the indirect approach the mass fractions of all impurities, in other words all elements excepting the matrix element, are measured and their sum is subtracted from the value for ideal purity, which is 1 kg/kg. Uncertainties at the 10 -4 level are aimed at because high purity metals are not only destined for being used as convenient primary realisations of the SI unit, but also as primary assays or so-called back-spikes in double isotope dilution mass spectrometry (IDMS). With double IDMS combined uncertainties down to 5·10 -4 can be achieved and therefore the uncertainty on the purity statement for these materials should be at or even lower than 10 -4 relative in order not to compromise the IDMS results.As a first step, only six metallic impurities are considered in previous studies and also in this comparison, in order to limit the effort within this study. Other metallic and non-metallic impurities might be subject to future CCQM studies. Zinc was chosen as matrix, due to its ease of...

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mentioning

confidence: 99%

Final report of the key comparison CCQM-K72: Purity of zinc with respect to six defined metallic analytes

Vogl¹,

Kipphardt²,

Torres³

et al. 2014

Metrologia

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“…Nesse modelo são realizadas, sob condições de repetitividade, medições simultâneas das amostras estocadas sob diferentes condições de temperatura, para produzir variações na taxa de deterioração dos agrotóxicos (LAMBERTY; SCHIMMEL; PAUWELS, 1998;van der VEEN et al, 2001;LINSINGER et al, 2001b;LINSINGER et al, 2004;INTERNATIONAL ORGANIZATION FOR STANDARDIZATION, 2006), ou seja, é possível através de uma única sequência de análise, utilizando a mesma curva analítica, realizar a avaliação dos resultados de medição sucessiva, levando a incertezas menores que aquelas decorrentes da utilização do modelo clássico e que, na maioria das vezes, podem ser negligenciadas. A extensão do tempo de estudo pode ser de dois meses, podendo se estender até seis a doze meses, visando-se obter informações adicionais sobre o tempo de estocagem (INTERNATIONAL ORGANIZATION FOR STANDARDIZATION, 2006).…”

Section: Soluções De Fortificaçãounclassified

“…Neste caso, se |b 1 | < t (0,95, n-2) * s(b 1 ), indicará que o material tem estabilidade garantida, ou seja, a inclinação da regressão é insignificante (LINSINGER et al, 2001b;INTERNATIONAL ORGANIZATION FOR STANDARDIZATION, 2006). Os parâmetros b 1 (inclinação da linha de regressão, indicado como o coeficiente da variável X 1) e s(b 1 ) (desvio padrão da inclinação, indicado como erro padrão da variável X 1) são apresentados na Tabela 3, obtidos pela função 'análise de regressão' do programa Windows/Excel®.…”

Section: Estudo Piloto I -Tratamento Por Pasteurizaçãounclassified

“…gama, respectivamente, uma extrapolação permite uma estimativa para o futuro, tendo em vista que a estabilidade observada durante esses períodos não asseguraria a priori a estabilidade nos períodos vindouros. Por conseguinte, a rigor, o INCQS-MRC01, deverá ter sua estabilidade monitorada também ao longo do período de estocagem (LINSINGER et al, 2001b).…”

Section: Agradecimentosunclassified

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Preparação de um material de referência certificado para controle de agrotóxicos em hortifrutigranjeiros: estudo da estabilidade

Cardoso¹,

Nóbrega²,

Vital³

et al. 2010

Ciênc. Tecnol. Aliment.

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A constante busca em garantir a qualidade e confiabilidade de uma medição obtida através de ensaios analíticos é o alvo prioritário em laboratórios nos dias de hoje. Uma ferramenta indicada para este objetivo é o uso de materiais de referência, certificados ou não, que apresentam como características essenciais homogeneidade e estabilidade conhecida. Cardoso (2008) apresentou os resultados referentes ao estudo da homogeneidade de um lote de polpa de tomate, candidata a material de referência certificado -MRC, fortificada com quatro agrotóxicos: γ-HCH, fenitrotiona, clorpirifós e procimidona. Assim como a homogeneidade, a estabilidade é também pré-requisito no processo de certificação do material de referência, pois constitui um importante parâmetro, indicativo do grau de conservação do material durante períodos específicos de tempo e temperatura após a sua preparação. Sabe-se que o material preparado pode ser suscetível à degradação por ação de agentes tais como: tempo, temperatura, luz, oxigênio, umidade, atividade microbiológica entre outros (INTERNATIONAL ORGANIZATION FOR STANDARDIZATION, 2006 AbstractThis research presents the results of stability studies regarding the production of certified reference materials. The residual concentration levels of four pesticides, namely γ-HCH, fenitrothion, chlorpyrifos, and procymidone were investigated. Pasteurization combined with gamma irradiation was used to maintain the integrity of the mixture tested as a reference material candidate. The pulp was prepared and split into two parts. Each part was then spiked with those pesticides in the concentration range of 0.1 to 0.2 mg.kg -1 in tomato pulp. One of them was submitted to pasteurization at 90 °C for 4 minutes after being homogenized, and the other was irradiated with a gamma dose of 2.0 kGy. The material stability and the corresponding uncertainty during the period of time evaluated were determined using regression analysis and ANOVA. The results indicated that the dose of 2.0 kGy was appropriated for the conservation of tomato pulp spiked with the four aforementioned pesticides. Keywords: pesticides; reference material; stability test; irradiation; pasteurization. ResumoNeste trabalho são apresentados os resultados dos estudos de estabilidade referentes à produção de um material de referência certificado. Foram avaliados níveis residuais de concentração dos agrotóxicos γ-HCH, fenitrotiona, clorpirifós e procimidona em polpa de tomate. A pasteurização e a irradiação gama foram empregadas à polpa de tomate, visando manter a integridade da amostra candidata a material de referência. A polpa foi preparada e dividida em duas partes. Cada parte foi fortificada com os referidos agrotóxicos na faixa de concentração de 0,1 a 0,2 mg.kg -1 . Uma das partes foi submetida à pasteurização a 90 °C por 4 minutos e a outra parte foi irradiada com dose de 2,0 kGy depois de homogeneizada. A estabilidade e a incerteza da amostra, correspondente ao período de tempo avaliado, foram determinadas através da análise de regressão em conj...

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“…The samples used in PTs need to be homogeneous in order to be sure that, when a laboratory result differs from those reported by other laboratories, the inconsistency can be attributed to analytical methods but not to the provided sample. Preparation of the homogeneous samples for proficiency testing schemes is a challenge for the PT organisers and the success depends on many parameters (5,6). Standard methods of homogeneity testing involve a duplicate analysis of at least 10 randomly selected samples.…”

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confidence: 99%

Homogeneity and Stability of Samples Used for Proficiency Testing in Enumeration of Coagulase Positive Staphylococci

Korpysa‐Dzirba

Rola

Osek

2012

Bulletin of the Veterinary Institute in Pulawy

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This study describes preparation of test samples composed of freeze-dried strain of S. aureus and powdered milk as a matrix. In the first part of the study, the number of S. aureus cells freeze-dried in skim milk or horse serum were compared at two levels of contamination (10 4 and 10 5 cfu g -1 ). The analysis of the samples was performed three times within a week. The preliminary results showed that the samples composed of S. aureus freeze-dried in horse serum were more stable and homogeneous than those prepared with skim milk. These results were further confirmed after analysing a higher number of such samples. Therefore, this procedure was then chosen for preparation of the samples for proficiency tests (PTs). Homogeneity and stability of these samples were checked according to ISO 13528. The results obtained showed that the samples met the criteria of stability and homogeneity required for PTs and were used in PT for enumeration of S. aureus in powdered milk.

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Homogeneity and stability of reference materials

Cited by 229 publications

References 1 publication

Final report of the key comparison CCQM-K72: Purity of zinc with respect to six defined metallic analytes

Final report of the key comparison CCQM-K72: Purity of zinc with respect to six defined metallic analytes

Preparação de um material de referência certificado para controle de agrotóxicos em hortifrutigranjeiros: estudo da estabilidade

Homogeneity and Stability of Samples Used for Proficiency Testing in Enumeration of Coagulase Positive Staphylococci

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