The ‘White Paper on Internationally Compatible Biofuels Standards’, published by a task force of biofuels experts from Brazil, the European Union, and the United States in 2007, recommended the “development of internationally-accepted reference methods and certified reference materials ... that underpin assessment of product quality, and help facilitate trade.” To meet this need, the Institute for Reference Materials and Measurements has released ERM-EF001, the first rapeseed-based biodiesel certified reference material, which is certified for selected parameters specified by the European Committee for Standardization in 2012 in standard EN 14214, i.e., the mass fraction of the ester, linolenic acid methyl ester, monoglyceride, diglyceride, triglyceride, total glycerol, and water content, density, viscosity, oxidation stability, acid value, iodine value, and flash point. All parameters are considered as method-defined measurands and can only be obtained by following the procedures specified in EN 14214. This article describes in detail the steps taken to produce this certified reference material.
No obstante, algunos investigadores han propuesto métodos para analizar esta familia de compuestos mediante gc. En 1991 Stan y Klaffenbach [8] proponen una reacción con anhídrido acético de 10 plaguicidas carbámicos para conseguir derivados térmicamente estables y volátiles para su posterior análisis mediante gc-ms. En 2006 Zhang y Lee [9] emplean una derivatización «en columna» para la determinación de 5 plaguicidas carbámicos en muestras acuosas tras una etapa de microextración en fase líquida. Lambropoulou et al. [10] evaluaron la contaminación de plaguicidas en el río Kalamas (Grecia) mediante spme y gc-ms. Entre los compuestos estudiados se incluye el Carbofurano, para el cual el método propuesto tiene un límite de detección de 0,03 µg /L. Lu y Que Hee [11] estudian la permeabilidad de los guantes de nitrilo al Metomilo mediante gc-ms. Con el fin de minimizar la descomposición del Metomilo se propone trabajar con temperaturas inferiores a 180°C. Algunos autores han propuesto dispositivos especiales para minimizar la degradación térmica de los plaguicidas carbámicos en gc. Por ejemplo, Wigfield et al. [12] recomiendan emplear columnas cortas (10 m), y un dispositivo
Within the Organic Analysis Working Group (OAWG) of the Comité Consultatif pour la Quantitè de Matiére (CCQM), key comparison CCQM-K141 and associated pilot study CCQM-P178 were coordinated by the National Research Council Canada (NRC). This comparison was a Track A key comparison that formed part of the OAWG 10-year strategic plan. The comparison demonstrated capabilities for measuring high-polarity analytes in a high-fat and high-protein matrix. The measurand chosen as the model system was enrofloxacin and sulfadiazine in bovine tissue. Thirteen National Metrology Institutes or Designated Institutes participated in the CCQM-K141, while two National Metrology Institutes participated in CCQM-P178. The bovine muscle tissue study material was derived from a single live animal that was administered with chemical based pharmaceutical agents prior to processing. Therefore, the study material was naturally incurred, providing a true test of extraction procedures relative to more commonly encountered spiked materials. NRC confirmed excellent homogeneity and stability of the material prior to shipping. Three 10 g bottles of freeze dried powdered muscle tissue were supplied. NRC also provided isotopically labelled solutions of the two measurands, 13C6-sulfadiazine and enrofloxacin-d5 (HI Salt), to those interested in using isotope dilution mass spectrometry (IDMS) methodologies. Procurement and purity assignment with appropriate metrological traceability of native calibrants were the responsibility of individual participants. The study required extraction, clean-up, analytical separation, and selective detection of the analytes. The level of agreement was reasonable given the measurands and matrix were new for most laboratories. The KCRV values and their uncertainties at the 95% confidence level of 57.81 ± 2.57 μg/kg for enrofloxacin and 2285 ± 68 μg/kg for sulfadiazine were calculated using the DSL means. While one participant's value was voluntarily excluded from the KCRV calculations for enrofloxacin, all other participants demonstrated equivalence for both measurands. Significant effort was undertaken post-study to identify the major sources of variability between results. In particular, the various extraction conditions used by participants were investigated thoroughly. While there appeared to be a correlation between highly acidic conditions and higher recovery, this was not definitive and could not be confirmed. The form of standards employed (i.e. free base vs salts) and potential differential solubility between forms was also a suspected source of variability. Biases could also have been introduced with the choice of solvents used for standard preparation, with some solvents better able to minimize adsorption of the analytes to glass surfaces. KEY WORDS FOR SEARCH enrofloxacin, sulfadiazine, bovine tissue, incurred, key comparison Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
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