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Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement (v.11, #1-2)
A global approach to method validation and measurement uncertainty by Max Feinberg; Michel Laurentie (pp. 3-9).
The enforcement of legal limits for food safety raises the question of decision-making in the context of uncertain measurements. It also puts the question of demonstrating that measurement technique that is used is fit for the purpose of controlling legal limits. A recent European Commision (EC) decision gives some indications how to deal with this question.In the meantime, the implementation of quality systems in analytical laboratories is now a reality. While these requirements deeply modified the organization of the laboratories, it has also improved the quality of the results.The goal of this communication is to describe how two fundamental requirements of ISO 17025 standard, i.e. validation of the methods and estimation of the uncertainty of measurements, can give a way to check whether an analytical method is correctly fit for the purpose of controlling legal limits. Both these requirements are not independent and it will be shown how they can be combined.A recent approach based on the “accuracy profile” of a method was applied to the determination of acrylamide and illustrates how uncertainty can be simply derived from the data collected for validating the method. Moreover, by basing on the β-expectation tolerance interval introduced by Mee [Technometrics (1984) 26(3): 251–253], it is possible to unambiguously demonstrate the fitness for purpose of a method.Remembering that the expression of uncertainty of the measurement is also a requirement for accredited laboratories, it is shown that the uncertainty can be easily related to the trueness and precision issuing from the data collected to build the method accuracy profile.The example presented here consists in validating a method for the determination of acrylamide in pig plasma by liquid chromatography–mass spectromery (LC–MS). Concentrations are expressed as mg/l and instrumental response is peak surface. The calibration experimental design included 5×5×2 measurements and namely consisted in preparing duplicate standard solutions at five concentration levels ranging from 10 to about 5000 mg/l. This was repeated for 5 days. The validation experimental design was similar.
Keywords: Method validation; Accuracy profile; Measurement uncertainty; Tolerance interval
A global approach to method validation and measurement uncertainty by Max Feinberg; Michel Laurentie (pp. 3-9).
The enforcement of legal limits for food safety raises the question of decision-making in the context of uncertain measurements. It also puts the question of demonstrating that measurement technique that is used is fit for the purpose of controlling legal limits. A recent European Commision (EC) decision gives some indications how to deal with this question.In the meantime, the implementation of quality systems in analytical laboratories is now a reality. While these requirements deeply modified the organization of the laboratories, it has also improved the quality of the results.The goal of this communication is to describe how two fundamental requirements of ISO 17025 standard, i.e. validation of the methods and estimation of the uncertainty of measurements, can give a way to check whether an analytical method is correctly fit for the purpose of controlling legal limits. Both these requirements are not independent and it will be shown how they can be combined.A recent approach based on the “accuracy profile” of a method was applied to the determination of acrylamide and illustrates how uncertainty can be simply derived from the data collected for validating the method. Moreover, by basing on the β-expectation tolerance interval introduced by Mee [Technometrics (1984) 26(3): 251–253], it is possible to unambiguously demonstrate the fitness for purpose of a method.Remembering that the expression of uncertainty of the measurement is also a requirement for accredited laboratories, it is shown that the uncertainty can be easily related to the trueness and precision issuing from the data collected to build the method accuracy profile.The example presented here consists in validating a method for the determination of acrylamide in pig plasma by liquid chromatography–mass spectromery (LC–MS). Concentrations are expressed as mg/l and instrumental response is peak surface. The calibration experimental design included 5×5×2 measurements and namely consisted in preparing duplicate standard solutions at five concentration levels ranging from 10 to about 5000 mg/l. This was repeated for 5 days. The validation experimental design was similar.
Keywords: Method validation; Accuracy profile; Measurement uncertainty; Tolerance interval
Estimation of measurement uncertainty for the determination of aflatoxin M1 in milk using immunoaffinity clean-up procedures by Giovanni Calaresu; Patrizia Piras; Gavina Carta; Roberta Galarini; Giannina Chessa (pp. 10-16).
A measurement uncertainty estimated for aflatoxin M1 determination in milk sample has been calculated using data generated from analytical method validation studies. The protocol adopted is described in detail in document LGC/VAM/1998/088. The uncertainty budget was based on precision, trueness and ruggedness data. The individual contributions are described in detail. The expanded uncertainty for aflatoxin M 1 at a concentration of 20 ng L−1 was estimated as 2.81 ng L−1. This was calculated using a coverage factor of two which gives a level of confidence of approximately 95%.
Keywords: Aflatoxin M1; Uncertainty; Precision; Trueness; Ruggedness
Estimation of measurement uncertainty for the determination of aflatoxin M1 in milk using immunoaffinity clean-up procedures by Giovanni Calaresu; Patrizia Piras; Gavina Carta; Roberta Galarini; Giannina Chessa (pp. 10-16).
A measurement uncertainty estimated for aflatoxin M1 determination in milk sample has been calculated using data generated from analytical method validation studies. The protocol adopted is described in detail in document LGC/VAM/1998/088. The uncertainty budget was based on precision, trueness and ruggedness data. The individual contributions are described in detail. The expanded uncertainty for aflatoxin M 1 at a concentration of 20 ng L−1 was estimated as 2.81 ng L−1. This was calculated using a coverage factor of two which gives a level of confidence of approximately 95%.
Keywords: Aflatoxin M1; Uncertainty; Precision; Trueness; Ruggedness
Estimation of uncertainty for the determination of mercury in food by CVAAS by M. Naceur Haouet; Giannina Chessa; Laura Fioroni; Roberta Galarini (pp. 17-22).
This paper is aimed at reporting a full validation of a Cold Vapour Atomic Absorption Spectrometry (CVAAS) method for mercury determination in fishery products. Method precision, trueness, limit of detection and limit of quantification are evaluated. The uncertainty of measurement is estimated following the bottom-up approach in conjunction with the validation data as suggested for complex analysis.The precision is evaluated using a pooled relative standard deviation and the recovery is added to the measurement uncertainty budget. Uncertainties of weight of sample, dilution factor, calibration, work solution and analyte amount are also assessed.The most relevant uncertainty sources result those associated to amount of mercury determined in the final sample solution, to method precision and to recovery. The relative contributions have different weights according to the analyst decision regarding recovery correction of results. In conclusion, the adopted CVAAS method fully complies with EU requirements.
Keywords: Mercury; CVAAS; Fish; Validation; Uncertainty
Estimation of uncertainty for the determination of mercury in food by CVAAS by M. Naceur Haouet; Giannina Chessa; Laura Fioroni; Roberta Galarini (pp. 17-22).
This paper is aimed at reporting a full validation of a Cold Vapour Atomic Absorption Spectrometry (CVAAS) method for mercury determination in fishery products. Method precision, trueness, limit of detection and limit of quantification are evaluated. The uncertainty of measurement is estimated following the bottom-up approach in conjunction with the validation data as suggested for complex analysis.The precision is evaluated using a pooled relative standard deviation and the recovery is added to the measurement uncertainty budget. Uncertainties of weight of sample, dilution factor, calibration, work solution and analyte amount are also assessed.The most relevant uncertainty sources result those associated to amount of mercury determined in the final sample solution, to method precision and to recovery. The relative contributions have different weights according to the analyst decision regarding recovery correction of results. In conclusion, the adopted CVAAS method fully complies with EU requirements.
Keywords: Mercury; CVAAS; Fish; Validation; Uncertainty
Validation of the Volhard method for chloride determination in food by M. Naceur Haouet; M. Serena Altissimi; Marisa Framboas; Roberta Galarini (pp. 23-28).
The aim of this paper is to compare the performance parameters of the Volhard method for chlorides determination obtained applying the bottom-up approach with those experimentally achieved. The method precision, trueness, detection and quantification limits and ruggedness are determined analysing various foods with different chloride contents. Otherwise, the measurement uncertainty is assessed applying the bottom-up approach using only pen and paper. The comparison between the performances established with both methods shows the validity of the metrological approach for volumetric procedures.
Keywords: Chloride; Volumetric; Validation; Uncertainty
Validation of the Volhard method for chloride determination in food by M. Naceur Haouet; M. Serena Altissimi; Marisa Framboas; Roberta Galarini (pp. 23-28).
The aim of this paper is to compare the performance parameters of the Volhard method for chlorides determination obtained applying the bottom-up approach with those experimentally achieved. The method precision, trueness, detection and quantification limits and ruggedness are determined analysing various foods with different chloride contents. Otherwise, the measurement uncertainty is assessed applying the bottom-up approach using only pen and paper. The comparison between the performances established with both methods shows the validity of the metrological approach for volumetric procedures.
Keywords: Chloride; Volumetric; Validation; Uncertainty
How can zero tolerances be controlled? The case study of Nitrofurans by Katrin Hoenicke; Robert Gatermann (pp. 29-32).
Nitrofurans comprise a group of antibiotic substances that have been used widely in the past in intensive farming of pigs, poultry, fishes, and shrimps. Studies in the late 1980s and early 1990s have proven that they are metabolised shortly after administration and form persistent residues that could be detected in the tissues of treated animals for weeks after administration. Both the nitrofurans as well as special metabolites have been classified as genotoxic compounds. No maximum residue limit (MRL) could be fixed either due to a lack of data or because the toxicological data did not support the derivation of an acceptable daily intake (ADI). Therefore, nitrofurans are listed in Annex IV of Council Regulation EEC No. 2377/90. From a regulatory point of view, any exposure to those substances is deemed a hazard to human health. Consequently Annex IV substances are controlled with zero tolerances.
Keywords: Nitrofurans; Semicarbazide; Zero tolerance; Contamination; Different sources; Legislation
How can zero tolerances be controlled? The case study of Nitrofurans by Katrin Hoenicke; Robert Gatermann (pp. 29-32).
Nitrofurans comprise a group of antibiotic substances that have been used widely in the past in intensive farming of pigs, poultry, fishes, and shrimps. Studies in the late 1980s and early 1990s have proven that they are metabolised shortly after administration and form persistent residues that could be detected in the tissues of treated animals for weeks after administration. Both the nitrofurans as well as special metabolites have been classified as genotoxic compounds. No maximum residue limit (MRL) could be fixed either due to a lack of data or because the toxicological data did not support the derivation of an acceptable daily intake (ADI). Therefore, nitrofurans are listed in Annex IV of Council Regulation EEC No. 2377/90. From a regulatory point of view, any exposure to those substances is deemed a hazard to human health. Consequently Annex IV substances are controlled with zero tolerances.
Keywords: Nitrofurans; Semicarbazide; Zero tolerance; Contamination; Different sources; Legislation
Product traceability in food-supply chains
by Prof. dr. ir. Jack G. A. J. van der Vorst (pp. 33-37).
Product traceability in food-supply chains
by Prof. dr. ir. Jack G. A. J. van der Vorst (pp. 33-37).
Dioxin analysis in feed: cell-based assay versus mass spectrometry method by Marie-Louise Scippo; Soledad Rybertt; Gauthier Eppe; Anne-Cécile Massart; Edwin De Pauw; Guy Maghuin-Rogister (pp. 38-43).
In the determination of contaminants (dioxins, polychlorinated biphenyls, polyaromatic hydrocarbons), cell-based assays are useful methods for screening purposes: they are mainly characterized by high sample throughput and lower costs than the Mass Spectrometry (MS)-based methods.Although cell-based assays can be sensitive enough for the determination of dioxins and related substances in agreement with the presently tolerable limits in food and feed (Regulation No. 2375/2001/EC and Directive 2003/57/EC respectively), their lack of specificity make their use rather questionable in control laboratories.In this paper, we present and compare results obtained from the analysis of a limited number of feed samples by both gas chromatography-high resolution mass spectrometry (GC-HRMS) and cell-based assay (DR-CALUX: dioxin responsive-chemically activated luciferase gene expression) methods. The DR-CALUX screening led to less than 10% false non-compliant and no false compliant results. In addition, there is a good correlation between GC-HRMS and DR-CALUX data. However, these preliminary results have to be confirmed on a larger number of samples to demonstrate that total toxic equivalent (TEQ), including dioxins, furans and dioxin-like polychlorobiphenyls (PCBs) can be monitored in feed and food with a cell-based assay.
Keywords: Dioxin responsive-chemically activated luciferase gene expression (DR-CALUX); Polychlorinated dibenzo-p-dioxins (PCDDs); Polychlorinated dibenzofurans (PCDFs); Polychlorinated biphenyls (PCBs); Screening; Dioxin; Feed; Food
Dioxin analysis in feed: cell-based assay versus mass spectrometry method by Marie-Louise Scippo; Soledad Rybertt; Gauthier Eppe; Anne-Cécile Massart; Edwin De Pauw; Guy Maghuin-Rogister (pp. 38-43).
In the determination of contaminants (dioxins, polychlorinated biphenyls, polyaromatic hydrocarbons), cell-based assays are useful methods for screening purposes: they are mainly characterized by high sample throughput and lower costs than the Mass Spectrometry (MS)-based methods.Although cell-based assays can be sensitive enough for the determination of dioxins and related substances in agreement with the presently tolerable limits in food and feed (Regulation No. 2375/2001/EC and Directive 2003/57/EC respectively), their lack of specificity make their use rather questionable in control laboratories.In this paper, we present and compare results obtained from the analysis of a limited number of feed samples by both gas chromatography-high resolution mass spectrometry (GC-HRMS) and cell-based assay (DR-CALUX: dioxin responsive-chemically activated luciferase gene expression) methods. The DR-CALUX screening led to less than 10% false non-compliant and no false compliant results. In addition, there is a good correlation between GC-HRMS and DR-CALUX data. However, these preliminary results have to be confirmed on a larger number of samples to demonstrate that total toxic equivalent (TEQ), including dioxins, furans and dioxin-like polychlorobiphenyls (PCBs) can be monitored in feed and food with a cell-based assay.
Keywords: Dioxin responsive-chemically activated luciferase gene expression (DR-CALUX); Polychlorinated dibenzo-p-dioxins (PCDDs); Polychlorinated dibenzofurans (PCDFs); Polychlorinated biphenyls (PCBs); Screening; Dioxin; Feed; Food
Determination of concentration levels of anticoccidials in eggs due to the presence of low levels of those compounds in feed for laying hens caused by carryover at the feeding mill*
by E. Daeseleire; L. Mortier; P. Delahaut; G. Huyghebaert (pp. 44-48).
Determination of concentration levels of anticoccidials in eggs due to the presence of low levels of those compounds in feed for laying hens caused by carryover at the feeding mill*
by E. Daeseleire; L. Mortier; P. Delahaut; G. Huyghebaert (pp. 44-48).
The European Food Legislation and its impact on honey sector by Biagio Fallico; Elena Arena; Antonella Verzera; Mario Zappalà (pp. 49-54).
The paper discusses the role of EC Directive 2001/110 on honey trading. Authors have demonstrated that, being the amount of developed hydroxymenthylfurfural (HMF) also correlated to honey chemical composition, the limit of 15mgLg, in low enzume honeys, is unjustifiable and become a barrier to trade for some unifloral honeys (citrus)
Keywords: Honey standards; HMF
The European Food Legislation and its impact on honey sector by Biagio Fallico; Elena Arena; Antonella Verzera; Mario Zappalà (pp. 49-54).
The paper discusses the role of EC Directive 2001/110 on honey trading. Authors have demonstrated that, being the amount of developed hydroxymenthylfurfural (HMF) also correlated to honey chemical composition, the limit of 15mgLg, in low enzume honeys, is unjustifiable and become a barrier to trade for some unifloral honeys (citrus)
Keywords: Honey standards; HMF
Food safety: screening tests used to detect and quantify GMO proteins by Monica Ermolli; Anna Fantozzi; Massimiliano Marini; Domenico Scotti; Branko Balla; Sebastian Hoffmann; Maddalena Querci; Claudia Paoletti; Guy Van den Eede (pp. 55-57).
GMO protein content in maize flours or fresh crops can be easily assessed by the enzyme-linked immunosorbent assays (ELISA) and immunochromatographic (lateral flow) strip tests commercially available. Therefore, ELISA can be seen as a useful tool for screening, for control purposes and for traceability implementation. In order to highlight the importance of monitoring GMO protein presence in food products and to investigate the performance of representative ELISA commercial kits, we evaluated three commercial kits by measuring the amount of Cry1Ab/Cry1Ac in IRMM certified reference materials.
Keywords: GMO; Immunoassay; ELISA; Cry 1Ab
Food safety: screening tests used to detect and quantify GMO proteins by Monica Ermolli; Anna Fantozzi; Massimiliano Marini; Domenico Scotti; Branko Balla; Sebastian Hoffmann; Maddalena Querci; Claudia Paoletti; Guy Van den Eede (pp. 55-57).
GMO protein content in maize flours or fresh crops can be easily assessed by the enzyme-linked immunosorbent assays (ELISA) and immunochromatographic (lateral flow) strip tests commercially available. Therefore, ELISA can be seen as a useful tool for screening, for control purposes and for traceability implementation. In order to highlight the importance of monitoring GMO protein presence in food products and to investigate the performance of representative ELISA commercial kits, we evaluated three commercial kits by measuring the amount of Cry1Ab/Cry1Ac in IRMM certified reference materials.
Keywords: GMO; Immunoassay; ELISA; Cry 1Ab
Evaluation of the limit of performance of an analytical method based on a statistical calculation of its critical concentrations according to ISO standard 11843: Application to routine control of banned veterinary drug residues in food according to European Decision 657/2002/EC by E. Verdon; D. Hurtaud-Pessel; P. Sanders (pp. 58-62).
Traceability of the measurement of analytical parameters capable of evaluating the performance of methods is an important concept for the assessment of quality for the routine control, especially for residue monitoring of non-authorized medicinal substances in food from animal origin. The European Decision no. 657/2002/EC recommends to calculate two statistical limits, CCα and CCβ, which allow to evaluate the critical concentrations above which the method reliably distinguish and quantify a substance taking into account the variability of the method and the statistical risk to take a wrong decision. The calculation, which can be derived from the ISO standard no. 11843 is applied on a routine basis. An example displays a very simple way for evaluating the performance of an LC-MSMS method which has been validated a few years ago and is qualified onto a Micromass Quattro LCZ tandem mass spectrometer to monitor and confirm the nitrofuran metabolite residues in food from animal origin.
Keywords: Traceability of analytical parameters; Analytical performance on routine control; Statistical calculation; ISO 11843 standard; Critical concentration; Limit of decision; Capacity of detection; Veterinary drug residue monitoring; Nitrofuran metabolites; Liquid chromatography hyphenated to tandem mass spectrometry (LC-MSMS)
Evaluation of the limit of performance of an analytical method based on a statistical calculation of its critical concentrations according to ISO standard 11843: Application to routine control of banned veterinary drug residues in food according to European Decision 657/2002/EC by E. Verdon; D. Hurtaud-Pessel; P. Sanders (pp. 58-62).
Traceability of the measurement of analytical parameters capable of evaluating the performance of methods is an important concept for the assessment of quality for the routine control, especially for residue monitoring of non-authorized medicinal substances in food from animal origin. The European Decision no. 657/2002/EC recommends to calculate two statistical limits, CCα and CCβ, which allow to evaluate the critical concentrations above which the method reliably distinguish and quantify a substance taking into account the variability of the method and the statistical risk to take a wrong decision. The calculation, which can be derived from the ISO standard no. 11843 is applied on a routine basis. An example displays a very simple way for evaluating the performance of an LC-MSMS method which has been validated a few years ago and is qualified onto a Micromass Quattro LCZ tandem mass spectrometer to monitor and confirm the nitrofuran metabolite residues in food from animal origin.
Keywords: Traceability of analytical parameters; Analytical performance on routine control; Statistical calculation; ISO 11843 standard; Critical concentration; Limit of decision; Capacity of detection; Veterinary drug residue monitoring; Nitrofuran metabolites; Liquid chromatography hyphenated to tandem mass spectrometry (LC-MSMS)
Uncertainty and traceability in an assay method (ascorbic acid in juices) by Alejandro Barragán Ocaña; María de los Ángeles Patricia Olvera Treviño (pp. 63-68).
We discus two of the most important aspects for ensuring the quality of the measurements in an assay method. These parameters are: measurement uncertainty and traceability of the measuring method. To be able to exemplify these parameters, we took as an example the measuring of ascorbic acid in commercial juices to clearly understand all the implicit metrological requirements in an assay method. To do this, it was necessary to meticulously analyze every step of the ascorbic acid measuring process via implementation of the practical application of the AOAC 967.21 Official Method for determining ascorbic acid, which is a titrimetric method based on the ISO 10012 norm. The uncertainty and traceability were studied and applied to control the process variability on the assay method. All this allows us to show the importance of implementing a measurement control system on an assay method, thus guaranteeing repeatable and traceable measurements, and ensuring that the measurements have been done accurately.
Keywords: Quality assurance; Metrology; Method; Traceability; Measurement uncertainty
Uncertainty and traceability in an assay method (ascorbic acid in juices) by Alejandro Barragán Ocaña; María de los Ángeles Patricia Olvera Treviño (pp. 63-68).
We discus two of the most important aspects for ensuring the quality of the measurements in an assay method. These parameters are: measurement uncertainty and traceability of the measuring method. To be able to exemplify these parameters, we took as an example the measuring of ascorbic acid in commercial juices to clearly understand all the implicit metrological requirements in an assay method. To do this, it was necessary to meticulously analyze every step of the ascorbic acid measuring process via implementation of the practical application of the AOAC 967.21 Official Method for determining ascorbic acid, which is a titrimetric method based on the ISO 10012 norm. The uncertainty and traceability were studied and applied to control the process variability on the assay method. All this allows us to show the importance of implementing a measurement control system on an assay method, thus guaranteeing repeatable and traceable measurements, and ensuring that the measurements have been done accurately.
Keywords: Quality assurance; Metrology; Method; Traceability; Measurement uncertainty
The importance of impurity analysis in pharmaceutical products: an integrated approach by Nafisur Rahman; Syed Najmul Hejaz Azmi; Hui-Fen Wu (pp. 69-74).
To purify a material and remove the excess impurities one should first recognize that whether they are actually present and what their nature is. In the past, this was not always done. But presently drug analysis and pharmaceutical impurities are the subjects of constant review in the public interest. The International Conference on Harmonisation (ICH) guidelines achieved a great deal in harmonizing the definitions of the impurities in new drug substances. It is necessary to perform all the investigations on appropriate reference standards of drug and impurities to get meaningful specifications. In order to meet the challenges to ensure high degree of purity of drug substances and drug products, a scheme is proposed for profiling drug impurity. Finally, analytical methods based on analytical instrumentation must be employed to quantitate drug substance and its impurities. Important aspects and suggestions related to drug analysis and pharmaceutical impurities are discussed.
Keywords: Drug analysis; Pharmaceutical impurities; Drug impurity profiling; Drug purity
The importance of impurity analysis in pharmaceutical products: an integrated approach by Nafisur Rahman; Syed Najmul Hejaz Azmi; Hui-Fen Wu (pp. 69-74).
To purify a material and remove the excess impurities one should first recognize that whether they are actually present and what their nature is. In the past, this was not always done. But presently drug analysis and pharmaceutical impurities are the subjects of constant review in the public interest. The International Conference on Harmonisation (ICH) guidelines achieved a great deal in harmonizing the definitions of the impurities in new drug substances. It is necessary to perform all the investigations on appropriate reference standards of drug and impurities to get meaningful specifications. In order to meet the challenges to ensure high degree of purity of drug substances and drug products, a scheme is proposed for profiling drug impurity. Finally, analytical methods based on analytical instrumentation must be employed to quantitate drug substance and its impurities. Important aspects and suggestions related to drug analysis and pharmaceutical impurities are discussed.
Keywords: Drug analysis; Pharmaceutical impurities; Drug impurity profiling; Drug purity
Evaluation of measurement uncertainty for thermometers with calibration equations by Chiachung Chen (pp. 75-82).
The method recommended by Eurachem did not mention the effect of adequateness of calibration equations on the measurement uncertainty. In this work, the sources of measurement uncertainty for two types of thermometer were evaluated. Three calibration equations were adopted to compare its predictive performance. These sources of combined uncertainty include predicted values of calibration equation, nonlinearity and repeatability, reference source, and resolution source. The uncertainty analysis shows that the predicted uncertainly of calibration equations is the main source for two types of thermometer. No significant difference of the uncertainty was found between the classical method and the inverse method. However, the calculation procedure of the inverse method was simpler and easier than that of the classical method.
Keywords: Uncertainty; Calibration equation; Nonlinearity
Evaluation of measurement uncertainty for thermometers with calibration equations by Chiachung Chen (pp. 75-82).
The method recommended by Eurachem did not mention the effect of adequateness of calibration equations on the measurement uncertainty. In this work, the sources of measurement uncertainty for two types of thermometer were evaluated. Three calibration equations were adopted to compare its predictive performance. These sources of combined uncertainty include predicted values of calibration equation, nonlinearity and repeatability, reference source, and resolution source. The uncertainty analysis shows that the predicted uncertainly of calibration equations is the main source for two types of thermometer. No significant difference of the uncertainty was found between the classical method and the inverse method. However, the calculation procedure of the inverse method was simpler and easier than that of the classical method.
Keywords: Uncertainty; Calibration equation; Nonlinearity
Compliance decision criteria—problems encountered and actions taken in the EU and Codex by Roger Wood (pp. 83-88).
It is now recognised that there is an intimate relationship between the final analytical result and the sampling, the measurement uncertainty and the recovery factor used to obtain that result. Within the food sector in the EU this was identified by the SCOOP Task 9.1 “Preparation Of A Working Document In Support Of The Uniform Interpretation Of Legislative Standards And The Laboratory Quality Standards Prescribed Under Directive 93/99/EEC”. The recommendations from this Report have been accepted in the Food Contaminants and the Undesirable Substances in Feed Sectors. These are given in the SANCO document “Report To The Standing Committee On The Food Chain And Animal Health On The Relationship Between Analytical Results, The Measurement Uncertainty, Recovery Factors And The Provisions In EU Food And Feed Legislation With Particular Focus On The Community Legislation Concerning: (A): Contaminants In Food (Council Regulation (EEC) No 315/93 of 8 February 1993 Laying Down Community Procedures For Contaminants In Food), and (B): Undesirable Substances In Feed (Directive 2002/32/EC Of The European Parliament And Of The Council Of 7 May 2002 On Undesirable Substances In Animal Feed).” Similar considerations were identified in the Codex Alimentations Commission where the guidelines “The Use Of Analytical Results: Sampling, Relationship Between The Analytical Results, The Measurement Uncertainty, Recovery Factors And The Provisions In Codex Standards” are being progressed through the Codex system. Both of these Reports stress that before deciding whether a sample is in compliance with a legislative limit the uncertainty should be deducted and the results corrected for recovery. Thus that there is a difference between the legal specification and enforcement limit will be stressed and that this should be appreciated when specifications are being set. The rationale behind the Reports is described.
Keywords: Compliance; Measurement uncertainty; Sampling; Recovery corrections; EU; Codex
Compliance decision criteria—problems encountered and actions taken in the EU and Codex by Roger Wood (pp. 83-88).
It is now recognised that there is an intimate relationship between the final analytical result and the sampling, the measurement uncertainty and the recovery factor used to obtain that result. Within the food sector in the EU this was identified by the SCOOP Task 9.1 “Preparation Of A Working Document In Support Of The Uniform Interpretation Of Legislative Standards And The Laboratory Quality Standards Prescribed Under Directive 93/99/EEC”. The recommendations from this Report have been accepted in the Food Contaminants and the Undesirable Substances in Feed Sectors. These are given in the SANCO document “Report To The Standing Committee On The Food Chain And Animal Health On The Relationship Between Analytical Results, The Measurement Uncertainty, Recovery Factors And The Provisions In EU Food And Feed Legislation With Particular Focus On The Community Legislation Concerning: (A): Contaminants In Food (Council Regulation (EEC) No 315/93 of 8 February 1993 Laying Down Community Procedures For Contaminants In Food), and (B): Undesirable Substances In Feed (Directive 2002/32/EC Of The European Parliament And Of The Council Of 7 May 2002 On Undesirable Substances In Animal Feed).” Similar considerations were identified in the Codex Alimentations Commission where the guidelines “The Use Of Analytical Results: Sampling, Relationship Between The Analytical Results, The Measurement Uncertainty, Recovery Factors And The Provisions In Codex Standards” are being progressed through the Codex system. Both of these Reports stress that before deciding whether a sample is in compliance with a legislative limit the uncertainty should be deducted and the results corrected for recovery. Thus that there is a difference between the legal specification and enforcement limit will be stressed and that this should be appreciated when specifications are being set. The rationale behind the Reports is described.
Keywords: Compliance; Measurement uncertainty; Sampling; Recovery corrections; EU; Codex
Can Legal Limits for GMO be enforced? by Bert Popping (pp. 89-93).
Labelling requirements for genetically modified organisms state that any product, containing or consisting of GMOs or products thereof, above a threshold of 0.9% need to be labelled accordingly. Reviewing projects of the UK Food Standards Agency on determination of GMO percentage in processed products as well as problems with certain series of Roundup Ready soybean certified reference materials, it seems impossible to accurately analyse any product for their GMO content and get the percentage right. The articles discusses analytical problems and pitfalls and shows what can and cannot be enforced.
Can Legal Limits for GMO be enforced? by Bert Popping (pp. 89-93).
Labelling requirements for genetically modified organisms state that any product, containing or consisting of GMOs or products thereof, above a threshold of 0.9% need to be labelled accordingly. Reviewing projects of the UK Food Standards Agency on determination of GMO percentage in processed products as well as problems with certain series of Roundup Ready soybean certified reference materials, it seems impossible to accurately analyse any product for their GMO content and get the percentage right. The articles discusses analytical problems and pitfalls and shows what can and cannot be enforced.
Estimation of measurement uncertainty in food microbiology: The ISO approach by Bertrand Lombard (pp. 94-100).
Given the current interest in measurement uncertainty (MU) in food microbiology, in particular for laboratory accreditation purposes, and the need to have harmonized reference documents specifically in that area at the international level, ISO is conducting works to meet this need. An ISO Technical Specification (ISO/TS 19036) is being prepared on MU estimation for quantitative determinations. A global approach has been chosen, based on the reproducibility standard deviation of the final result of the measurement process. Three possibilities are envisaged for the estimation of the reproducibility standard deviation, in a decreasing order of preference: The intra-laboratory standard deviation, the inter-laboratory standard deviation derived from method validation, and the inter-laboratory standard deviation derived from proficiency testing.The uncertainty of qualitative determinations is still under investigation, and will be covered by a separate ISO publication.
Keywords: Food; Microbiology; Measurement uncertainty; ISO
Estimation of measurement uncertainty in food microbiology: The ISO approach by Bertrand Lombard (pp. 94-100).
Given the current interest in measurement uncertainty (MU) in food microbiology, in particular for laboratory accreditation purposes, and the need to have harmonized reference documents specifically in that area at the international level, ISO is conducting works to meet this need. An ISO Technical Specification (ISO/TS 19036) is being prepared on MU estimation for quantitative determinations. A global approach has been chosen, based on the reproducibility standard deviation of the final result of the measurement process. Three possibilities are envisaged for the estimation of the reproducibility standard deviation, in a decreasing order of preference: The intra-laboratory standard deviation, the inter-laboratory standard deviation derived from method validation, and the inter-laboratory standard deviation derived from proficiency testing.The uncertainty of qualitative determinations is still under investigation, and will be covered by a separate ISO publication.
Keywords: Food; Microbiology; Measurement uncertainty; ISO
Report on the TDRM symposia at the 119th AOAC annual meeting, Orlando, Florida, USA, 13 September 2005 by Hendrik Emons (pp. 101-102).
The two reference material symposia of the last AOAC Annual Meeting are summarized.
Keywords: Reference materials; TDRM; AOAC; Microbiology; Quality control
Report on the TDRM symposia at the 119th AOAC annual meeting, Orlando, Florida, USA, 13 September 2005 by Hendrik Emons (pp. 101-102).
The two reference material symposia of the last AOAC Annual Meeting are summarized.
Keywords: Reference materials; TDRM; AOAC; Microbiology; Quality control