Forgot your password?
New user?
New Window Opens on the Secret Life of Microbes: Scientists Develop First Microbial Profiles of Ecosystems
CAS announces the release of SciFinder Scholar for Mac OS X
Press Releases
Press Releases
| Check out our New Publishers' Select for Free Articles |
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement (v.15, #4)
BERM: the international forum for reference material producers and users
by Mike Sargent (pp. 205-205).
BERM: the international forum for reference material producers and users
by Mike Sargent (pp. 205-205).
Standardization in allergen determination by Markus Lacorn; Ulrike Immer (pp. 207-216).
An overview is given of sensitization and allergic reaction on food, along with minimal eliciting doses for selected allergens (milk, egg, peanut), followed by the legislative situation in the European Community, the USA, Canada, Australia/New Zealand and Japan. The main focus of the paper discusses methods for food allergen determination (chromatography, DNA-based, antibody-based) and their limitations. Special emphasis is given on antibody-based systems, which are at the moment the most advanced and validated methods available. Examples are given of the current status of standardization for egg, milk, nuts, prolamins, glutelins and for clinical validated reference samples from the EU project EuroPrevall. Recommendations for ongoing activities are also included.
Keywords: Allergen; ELISA; Standardization; Calibrant; Reference materials
Standardization in allergen determination by Markus Lacorn; Ulrike Immer (pp. 207-216).
An overview is given of sensitization and allergic reaction on food, along with minimal eliciting doses for selected allergens (milk, egg, peanut), followed by the legislative situation in the European Community, the USA, Canada, Australia/New Zealand and Japan. The main focus of the paper discusses methods for food allergen determination (chromatography, DNA-based, antibody-based) and their limitations. Special emphasis is given on antibody-based systems, which are at the moment the most advanced and validated methods available. Examples are given of the current status of standardization for egg, milk, nuts, prolamins, glutelins and for clinical validated reference samples from the EU project EuroPrevall. Recommendations for ongoing activities are also included.
Keywords: Allergen; ELISA; Standardization; Calibrant; Reference materials
Development of a new reference material for the validation of molecular detection methods for microbiological analysis by Raquel Múrtula; M. Adela Yáñez; Elena Soria; Vicente Catalán (pp. 217-221).
The standard methodology used for the detection of bacteria in environmental samples and food is primarily based on bacterial growth on specific culture media and confirmation by biochemical and/or immunological tests of all presumptive colonies. However, this methodology presents a number of drawbacks, such as low sensitivity and specificity, and the long time needed to obtain results. For this reason, the implementation of molecular methods in diagnostic laboratories has increased over the past several years. Nevertheless, most of these newer methods have not been included in current legislation, and, in most of cases, they have not yet been normalized. In this sense, the availability of appropriate reference materials (RMs) can help to overcome these deficiencies. The aim of this study was to develop and validate, following ISO Guide 34, a new RM, in a tablet format, for the quantification of Legionella pneumophila and Salmonella spp. by quantitative PCR (qPCR). This new RM can be used as a work reference sample in internal quality control, in the organization of proficiency testing schemes (PTS), as well as for the validation of molecular methods based on qPCR.
Keywords: Reference material; Microbiology; Molecular methods; qPCR
Development of a new reference material for the validation of molecular detection methods for microbiological analysis by Raquel Múrtula; M. Adela Yáñez; Elena Soria; Vicente Catalán (pp. 217-221).
The standard methodology used for the detection of bacteria in environmental samples and food is primarily based on bacterial growth on specific culture media and confirmation by biochemical and/or immunological tests of all presumptive colonies. However, this methodology presents a number of drawbacks, such as low sensitivity and specificity, and the long time needed to obtain results. For this reason, the implementation of molecular methods in diagnostic laboratories has increased over the past several years. Nevertheless, most of these newer methods have not been included in current legislation, and, in most of cases, they have not yet been normalized. In this sense, the availability of appropriate reference materials (RMs) can help to overcome these deficiencies. The aim of this study was to develop and validate, following ISO Guide 34, a new RM, in a tablet format, for the quantification of Legionella pneumophila and Salmonella spp. by quantitative PCR (qPCR). This new RM can be used as a work reference sample in internal quality control, in the organization of proficiency testing schemes (PTS), as well as for the validation of molecular methods based on qPCR.
Keywords: Reference material; Microbiology; Molecular methods; qPCR
New reference material for analysis of elements in glutinous rice produced at the National Institute of Metrology (Thailand) by Charun Yafa; Sirinapha Srithongtim; Pranee Phukphatthanachai; Araya Thiparuk; Nittaya Sudsiri; Laddawan Rojanapantip; Mayuree Uraroongroj; Panawan Kluengklangdon; Preeyaporn Jaengkarnkit; Kittipong Sirisuthanant; Chamoy Thonglue; Thanida Pimma; Paramee Pengpreecha; Tippaya Julwee Fortune; Ratirot Zwicker; Vorapot Permnamtip; Sirinart Laoharojanaphnad; Boonlert Suanmamuang; Juwadee Shiowatana; Weerawan Waiyawat; Atitaya Siripinyanond; Kunchit Judprasong; Benjawan Boonsong; Suwaluck Talaluck; Chainarong Cherdchu (pp. 223-231).
Reference materials play an important role for evaluating the accuracy of analytical results, and are essential parts of good laboratory practice. They represent a key tool for quality control of chemical analyses. In Thailand, the demand of food and environmental reference materials is constantly increasing, and the National Institute of Metrology (NIMT, Thailand) is responding to the urgent needs for affordable materials, which require collaborative efforts at the national level. This paper describes the preparation of a new glutinous rice reference material, along with homogeneity and stability studies and the analytical work carried out for the certification of the contents of inorganic elements. The incurred material was collected from an actual rice paddy field. Material preparation along with homogeneity and stability testing were carried out at the Environmental Research Training Centre (ERTC). The homogeneity study was designed to have three experimental conditions; (A) 10 bottles of candidate materials being analyzed each with 2 replicates, (B) 20 bottles with 2 replicates, (C) 10 bottles with 7 replicates, in order to study the suitable treatments for homogeneity testing in the reference material production. It was shown that a minimum number of 10 bottles with duplicate analyses are enough to demonstrate the homogeneity of candidate reference material. Certification of a candidate reference material in a single laboratory using reference method was confirmed with an interlaboratory comparison participated by a certain number of well recognized testing laboratories in Thailand. Further elaborative results will be discussed.
Keywords: Inorganic analysis; Elements; Rice; Reference material
New reference material for analysis of elements in glutinous rice produced at the National Institute of Metrology (Thailand) by Charun Yafa; Sirinapha Srithongtim; Pranee Phukphatthanachai; Araya Thiparuk; Nittaya Sudsiri; Laddawan Rojanapantip; Mayuree Uraroongroj; Panawan Kluengklangdon; Preeyaporn Jaengkarnkit; Kittipong Sirisuthanant; Chamoy Thonglue; Thanida Pimma; Paramee Pengpreecha; Tippaya Julwee Fortune; Ratirot Zwicker; Vorapot Permnamtip; Sirinart Laoharojanaphnad; Boonlert Suanmamuang; Juwadee Shiowatana; Weerawan Waiyawat; Atitaya Siripinyanond; Kunchit Judprasong; Benjawan Boonsong; Suwaluck Talaluck; Chainarong Cherdchu (pp. 223-231).
Reference materials play an important role for evaluating the accuracy of analytical results, and are essential parts of good laboratory practice. They represent a key tool for quality control of chemical analyses. In Thailand, the demand of food and environmental reference materials is constantly increasing, and the National Institute of Metrology (NIMT, Thailand) is responding to the urgent needs for affordable materials, which require collaborative efforts at the national level. This paper describes the preparation of a new glutinous rice reference material, along with homogeneity and stability studies and the analytical work carried out for the certification of the contents of inorganic elements. The incurred material was collected from an actual rice paddy field. Material preparation along with homogeneity and stability testing were carried out at the Environmental Research Training Centre (ERTC). The homogeneity study was designed to have three experimental conditions; (A) 10 bottles of candidate materials being analyzed each with 2 replicates, (B) 20 bottles with 2 replicates, (C) 10 bottles with 7 replicates, in order to study the suitable treatments for homogeneity testing in the reference material production. It was shown that a minimum number of 10 bottles with duplicate analyses are enough to demonstrate the homogeneity of candidate reference material. Certification of a candidate reference material in a single laboratory using reference method was confirmed with an interlaboratory comparison participated by a certain number of well recognized testing laboratories in Thailand. Further elaborative results will be discussed.
Keywords: Inorganic analysis; Elements; Rice; Reference material
Long-term stability study on a Perna perna mussel candidate reference material by Edson Gonçalves Moreira; M. B. A. Vasconcellos; M. G. M. Catharino; V. A. Maihara; M. Saiki (pp. 233-238).
The long-term stability study, one of the steps in the characterization of new reference materials, is performed on freeze-dried biological reference materials to verify if they may be stored at room temperature without modification of the property values of interest. In this study, instrumental neutron activation analysis was used in a 12-month long isochronous long-term stability study performed on a Perna perna mussel candidate reference material. No trend in the results was observed in respect to measurement order and exposition period to room temperature. The assessment of the analysis of variance test as well as the normalized results to the control temperature showed no systematic changes in the mass fractions of Ag, As, Br, Co, Cr, Cs, Fe, Eu, La, Na, Rb, Sc, Se, Th and Zn during the test period. The result showed that the candidate reference material may be stored at room temperature without significant changes in composition for the determined elements.
Keywords: Reference material; Stability study; Mussel; Perna perna ; Neutron activation analysis; Trace elements
Long-term stability study on a Perna perna mussel candidate reference material by Edson Gonçalves Moreira; M. B. A. Vasconcellos; M. G. M. Catharino; V. A. Maihara; M. Saiki (pp. 233-238).
The long-term stability study, one of the steps in the characterization of new reference materials, is performed on freeze-dried biological reference materials to verify if they may be stored at room temperature without modification of the property values of interest. In this study, instrumental neutron activation analysis was used in a 12-month long isochronous long-term stability study performed on a Perna perna mussel candidate reference material. No trend in the results was observed in respect to measurement order and exposition period to room temperature. The assessment of the analysis of variance test as well as the normalized results to the control temperature showed no systematic changes in the mass fractions of Ag, As, Br, Co, Cr, Cs, Fe, Eu, La, Na, Rb, Sc, Se, Th and Zn during the test period. The result showed that the candidate reference material may be stored at room temperature without significant changes in composition for the determined elements.
Keywords: Reference material; Stability study; Mussel; Perna perna ; Neutron activation analysis; Trace elements
The results of HbA1c measurement and its comparison with reference method values in an EQA programme by Bedřich Friedecký; Josef Kratochvíla; Marek Budina; Ilona Šperlingová (pp. 239-243).
This article describes the effect of a change in reference method for HbA1c measurement on results in our EQA programme. Important indicators of analytical quality, particularly reproducibility, bias and uncertainty, were assessed. Basic analytical quality indicators for the measurement of HbA1c in an EQA survey during 2000–2008 were evaluated. Three EQA surveys per year were performed. Usually there were more than 200 participating laboratories in each survey. Reproducibility, systematic differences, bias, and methodology changes before and after IFCC reference method implementation were determined. In the EQA surveys, target values traceable to the IFCC reference method are used. Estimation of the combined uncertainty of the result was a voluntary part of the surveys and was reported by 50% of participating laboratories. Reproducibility of all participants’ measurements was close to the target value of CV = 5.0% (coefficient of variation). The group of participants using HPLC methodology had reproducibility lower than 5.0% in each survey, whilst the immunochemistry group usually had CV values more than 6.0%. The differences in individual results from target values ranged in the interval ±12% for HPLC methods but more (−8 to +30%) for immunochemistry methods. During the monitored time interval the number of participants using HPLC methods increased up to 70% whilst the number of participants using immunochemistry methods decreased approximately to 30%. The combined uncertainty (u c ) reported by participants varies between 4.0 and 4.5% for HbA1c values between 30 and 90 mmol/mol. No significant differences between precision and systematic errors (bias) after the implementation of IFCC method of measurement for HbA1c to routine processes for HPLC were observed. Immunochemical methods do not fulfil requirements for analytical reproducibility.
Keywords: HbA1c measurement; IFCC method; HPLC; Immunochemistry; Uncertainty; External quality assessment
The results of HbA1c measurement and its comparison with reference method values in an EQA programme by Bedřich Friedecký; Josef Kratochvíla; Marek Budina; Ilona Šperlingová (pp. 239-243).
This article describes the effect of a change in reference method for HbA1c measurement on results in our EQA programme. Important indicators of analytical quality, particularly reproducibility, bias and uncertainty, were assessed. Basic analytical quality indicators for the measurement of HbA1c in an EQA survey during 2000–2008 were evaluated. Three EQA surveys per year were performed. Usually there were more than 200 participating laboratories in each survey. Reproducibility, systematic differences, bias, and methodology changes before and after IFCC reference method implementation were determined. In the EQA surveys, target values traceable to the IFCC reference method are used. Estimation of the combined uncertainty of the result was a voluntary part of the surveys and was reported by 50% of participating laboratories. Reproducibility of all participants’ measurements was close to the target value of CV = 5.0% (coefficient of variation). The group of participants using HPLC methodology had reproducibility lower than 5.0% in each survey, whilst the immunochemistry group usually had CV values more than 6.0%. The differences in individual results from target values ranged in the interval ±12% for HPLC methods but more (−8 to +30%) for immunochemistry methods. During the monitored time interval the number of participants using HPLC methods increased up to 70% whilst the number of participants using immunochemistry methods decreased approximately to 30%. The combined uncertainty (u c ) reported by participants varies between 4.0 and 4.5% for HbA1c values between 30 and 90 mmol/mol. No significant differences between precision and systematic errors (bias) after the implementation of IFCC method of measurement for HbA1c to routine processes for HPLC were observed. Immunochemical methods do not fulfil requirements for analytical reproducibility.
Keywords: HbA1c measurement; IFCC method; HPLC; Immunochemistry; Uncertainty; External quality assessment
Certification of reference materials for inorganic trace analysis: the INCT approach by Halina Polkowska-Motrenko; Rajmund S. Dybczyński; Ewelina Chajduk (pp. 245-250).
This paper presents the work done by the Institute of Nuclear Chemistry and Technology (INCT), Warsaw on a procedure of the certification of matrix reference materials (CRMs) for inorganic trace analysis. The INCT has been involved in preparation and certification of that type of CRMs since 1986 till now. The certification of CRMs is performed on the basis of statistical evaluation of the data obtained from the worldwide interlaboratory comparison. The initially adopted certification procedure has been developed, and the final shape is presented and discussed. The modifications are connected with the new demands of the international standards. The results of analysis of candidate CRMs obtained by the potentially primary procedures based on radiochemical neutron activation analysis (RNAA) and results of analysis of CRM accompanying candidate RMs are applied in the certification process for quality assurance purpose.
Keywords: CRM; Certification; Radiochemical neutron activation analysis; RNAA primary procedure; Traceability
Certification of reference materials for inorganic trace analysis: the INCT approach by Halina Polkowska-Motrenko; Rajmund S. Dybczyński; Ewelina Chajduk (pp. 245-250).
This paper presents the work done by the Institute of Nuclear Chemistry and Technology (INCT), Warsaw on a procedure of the certification of matrix reference materials (CRMs) for inorganic trace analysis. The INCT has been involved in preparation and certification of that type of CRMs since 1986 till now. The certification of CRMs is performed on the basis of statistical evaluation of the data obtained from the worldwide interlaboratory comparison. The initially adopted certification procedure has been developed, and the final shape is presented and discussed. The modifications are connected with the new demands of the international standards. The results of analysis of candidate CRMs obtained by the potentially primary procedures based on radiochemical neutron activation analysis (RNAA) and results of analysis of CRM accompanying candidate RMs are applied in the certification process for quality assurance purpose.
Keywords: CRM; Certification; Radiochemical neutron activation analysis; RNAA primary procedure; Traceability
A review of proficiency testing scheme in Republic of Korea: in the field of water analysis by Young-Hee Kim; Jung-Sub Lee; Ki-Bong Song; Young-Yeul Kang; Sun-Kyoung Shin; Gi-Taeg Jung; Eun-Jin Hong; Hyun-Jeong Kim; Kum-Hee Kim (pp. 251-254).
For regulatory purposes, it is often required to check the quality of environmental chemical analyses by routine proficiency testing (PT). In this study, the PT scheme of environmental laboratories in Republic of Korea has been reviewed. Especially, real water-based reference materials (RMs) were prepared and distributed for PT schemes. The consensus values from the PT were calculated by robust statistics with its standard uncertainties. The relative bias between the reference values and the consensus values was used as one of the indicators for the determination of the assigned values. The relationship between the performances of the laboratories, expressed by Z scores, and the concentration levels of the RMs were also revealed.
Keywords: Proficiency testing; Consensus values; Z score; Real water-based reference materials
A review of proficiency testing scheme in Republic of Korea: in the field of water analysis by Young-Hee Kim; Jung-Sub Lee; Ki-Bong Song; Young-Yeul Kang; Sun-Kyoung Shin; Gi-Taeg Jung; Eun-Jin Hong; Hyun-Jeong Kim; Kum-Hee Kim (pp. 251-254).
For regulatory purposes, it is often required to check the quality of environmental chemical analyses by routine proficiency testing (PT). In this study, the PT scheme of environmental laboratories in Republic of Korea has been reviewed. Especially, real water-based reference materials (RMs) were prepared and distributed for PT schemes. The consensus values from the PT were calculated by robust statistics with its standard uncertainties. The relative bias between the reference values and the consensus values was used as one of the indicators for the determination of the assigned values. The relationship between the performances of the laboratories, expressed by Z scores, and the concentration levels of the RMs were also revealed.
Keywords: Proficiency testing; Consensus values; Z score; Real water-based reference materials
An approach for more precise statements of metrological traceability on reference material certificates by R. Koeber; T. P. J. Linsinger; H. Emons (pp. 255-262).
Metrological traceability of measurement results is a key requirement for the comparability of such data in time and space and with legal or product specifications. Similarly, traceability of the certified values of a certified reference material (CRM) is a prerequisite for their usefulness. Consequently, a statement on metrological traceability of the certified value of the specified property is a requirement of the ISO Guide series on Reference Materials. The establishment of the traceability of a value assigned to a property of a reference material to a stated reference is pivotal to the use of the material. Metrological traceability is related to a combination of four attributes that are assigned to a clearly identified sample: description of the property, description of the quantity/kind of quantity, a number with its corresponding uncertainty and the measurement unit. The first two items define the identity of the measurand, whereas the latter two describe the value that is assigned to this measurand. Therefore, the concept of traceability rests on two anchor points, namely identity and quantity value. The identity of a measurand can be defined by its structure alone or by an operational/procedural definition, the quantity value of the measurand can refer to the SI, or to an artefact, if standards of arbitrary values have been used for the calibration of equipment (e.g. WHO standards; international units). The presented approach splits traceability statements for CRMs into a description of the identity of the measurand and the quantity value and provides a solution to overcome the conflict as to whether a measurement result should be declared as traceable to the SI or traceable to a method.
Keywords: Metrological traceability; Certified reference materials; Quantity value; Identity; Traceability statement; Measurand
An approach for more precise statements of metrological traceability on reference material certificates by R. Koeber; T. P. J. Linsinger; H. Emons (pp. 255-262).
Metrological traceability of measurement results is a key requirement for the comparability of such data in time and space and with legal or product specifications. Similarly, traceability of the certified values of a certified reference material (CRM) is a prerequisite for their usefulness. Consequently, a statement on metrological traceability of the certified value of the specified property is a requirement of the ISO Guide series on Reference Materials. The establishment of the traceability of a value assigned to a property of a reference material to a stated reference is pivotal to the use of the material. Metrological traceability is related to a combination of four attributes that are assigned to a clearly identified sample: description of the property, description of the quantity/kind of quantity, a number with its corresponding uncertainty and the measurement unit. The first two items define the identity of the measurand, whereas the latter two describe the value that is assigned to this measurand. Therefore, the concept of traceability rests on two anchor points, namely identity and quantity value. The identity of a measurand can be defined by its structure alone or by an operational/procedural definition, the quantity value of the measurand can refer to the SI, or to an artefact, if standards of arbitrary values have been used for the calibration of equipment (e.g. WHO standards; international units). The presented approach splits traceability statements for CRMs into a description of the identity of the measurand and the quantity value and provides a solution to overcome the conflict as to whether a measurement result should be declared as traceable to the SI or traceable to a method.
Keywords: Metrological traceability; Certified reference materials; Quantity value; Identity; Traceability statement; Measurand
New IUPAC/CITAC guide available: Selection and use of proficiency testing schemes for a limited number of participants
(pp. 263-263).