5 research outputs found
Etude de stabilité des matériaux de référence externe (méthodes de modélisation et de contrôle)
PARIS-AgroParisTech Centre Paris (751052302) / SudocSudocFranceF
Comparison of shelf-life appraisal techniques for the estimation of the limiting date of stability for agrifood reference materials
International audienceReference materials play a major role for the verification of the quality control of biological and chemical analysis. Due to the poor availability of certified reference materials, external reference materials (ERM) are intensively developing in complement and as a consequence of proficiency testing schemes (PTS). However, the use of any reference material must be time-limited, whereas the assigned reference value may change with time and it is under the responsibility of the material producer to indicate the date until this can be used for calibration purpose with some guarantee. This article compares different methods used to determine the limiting date of stability (LDS) in food and food-related reference materials, using some specific analytes (moisture, protein and oil contents) as stability-monitoring analytes. LDS is defined as the moment when the assigned values of one or several analytes can no longer be guaranteed by the producer. For most of the ERMs used as examples (i.e., rapeseed, bread wheat, durum wheat) the calculated periods of stability were longer than the present storage times used in BIPEA. However, for sunflower, the rapid degradation of the monitoring analytes indicates a shorter time than forecast
Stability studies of agrifood reference materials under different conditions of storage by near-infrared spectroscopy
International audienceReference materials (R-M) play an increasingly important role for laboratories. The aim of this work is to compare different conditions of storage and assess the stability of agrifood external reference materials (ERM). These materials could be used as tools by laboratories notably for their quality control procedure. However, as the other RM, their stability must be assessed during stability studies. The determination of the limiting date of stability (LDS), defined as the period during which analytes called marker of stability arc still considered as stable, is used on this purpose. The influences of the environmental factor were tested by the application of full experimental designs with two tested environmental factors: the temperature (storage at +4 degrees C or +20 10 degrees C) and the composition of the atmosphere (absence or presence of gases in the packaging). Thus, the setting under vacuum increases clearly the stability for the studied analyte. Almost all ERM stored in the best conditions have a determined LDS higher than those stored in current condition of storage. Indeed, the bread wheat ERM LDS is higher than the current storage of 24 month
Application of the ANOVA-PCA method to stability studies of reference materials
International audienceNear infrared spectroscopy (NIRS) is an analytical technique that can be very useful for stability studies in particular because of its non destructive analytical capability. However, the spectral interpretation and treatment of this kind of multivariate data remains difficult without the use of chemometrics. In this article, a recent chemometrics method, analysis of variance - principal component analysis (ANOVA-PCA), was used for NIRS stability studies of sunflower and bread wheat external reference materials (ERM). It provided a practical tool for the study of the significance of various storage conditions according to an experimental design. Thus, the effect of the temperature, the nature of the atmosphere in the packaging and the storage duration were tested. ANOVA-PCA highlighted the influence of temperature and storage duration on the stability of the sunflower materials. For the bread wheat materials, the storage conditions did not have a significant effect on stability. Consequently, by applying ANOVA-PCA to near infrared spectral data, the sunflower materials were found to be considered stable for the time length of the study, i.e. 18 months stored in a cold room, while the bread wheat materials were found to be considered stable for the time length of the study, i.e. 12 months under the same conditions. (c) 2007 Elsevier B.V. All rights reserved