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Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement (v.10, #7)
The role of metrology in making chemistry sustainable by Günther Meinrath; Margarete Kalin (pp. 327-337).
Sustainable development is the new design of an old concept, now emerging from the acute endangering of our habitat. Coined by the Brundlandt Commission in 1987, sustainable development was defined as ‘Development that meets the needs of the present without compromising the ability of future generations to meet their own needs’ (World commission on Environment and Development, Our Common Future, Oxford University Press, Oxford, 1987). It appeared on the world stage during the UNO Earth Summit in Rio, 1992. Sustainability became the key term of the ‘Agenda 21’ (United Nations Conference for Education and Development, Earth Summit, Agenda 21, The United Nations Programme of action for Sustainable Development, United Nations, New York, 1992). The ‘Agenda 21’ is adopted by 178 states, although to date not all signatories have ratified the Agenda. Sustainable solutions should aim to harmonize ecological equilibrium, economic stability, and social harmony. But in the course of the years, the interpretation of the concept became more and more complicated and its context is becoming fuzzy.
The role of metrology in making chemistry sustainable by Günther Meinrath; Margarete Kalin (pp. 327-337).
Sustainable development is the new design of an old concept, now emerging from the acute endangering of our habitat. Coined by the Brundlandt Commission in 1987, sustainable development was defined as ‘Development that meets the needs of the present without compromising the ability of future generations to meet their own needs’ (World commission on Environment and Development, Our Common Future, Oxford University Press, Oxford, 1987). It appeared on the world stage during the UNO Earth Summit in Rio, 1992. Sustainability became the key term of the ‘Agenda 21’ (United Nations Conference for Education and Development, Earth Summit, Agenda 21, The United Nations Programme of action for Sustainable Development, United Nations, New York, 1992). The ‘Agenda 21’ is adopted by 178 states, although to date not all signatories have ratified the Agenda. Sustainable solutions should aim to harmonize ecological equilibrium, economic stability, and social harmony. But in the course of the years, the interpretation of the concept became more and more complicated and its context is becoming fuzzy.
Including correlation effects in an improved spreadsheet calculation of combined standard uncertainties by Stephen L. R. Ellison (pp. 338-343).
A spreadsheet method allowing rapid calculation of combined standard uncertainties is described. The model used allows explicitly for correlation effects, and requires a user to enter only the parameters, the calculation used to obtain the final result (including relevant influence factors), the individual standard uncertainties for the parameters, and estimates of correlation coefficients where necessary. The estimation of correlation coefficients in common cases is discussed, and it is shown that correlation is likely to be practically significant only when the correlated contribution to individual standard uncertainties is significantly over about 30% of the relevant standard uncertainty, leading to correlation coefficients |r| greater than 0.1. The implementation includes a more robust differentiation algorithm than previously reported for spreadsheet use, and initial preparation of the spreadsheets has been automated. The principle is illustrated with a simple example.
Keywords: Measurement uncertainty; Correlation; Spreadsheet
Including correlation effects in an improved spreadsheet calculation of combined standard uncertainties by Stephen L. R. Ellison (pp. 338-343).
A spreadsheet method allowing rapid calculation of combined standard uncertainties is described. The model used allows explicitly for correlation effects, and requires a user to enter only the parameters, the calculation used to obtain the final result (including relevant influence factors), the individual standard uncertainties for the parameters, and estimates of correlation coefficients where necessary. The estimation of correlation coefficients in common cases is discussed, and it is shown that correlation is likely to be practically significant only when the correlated contribution to individual standard uncertainties is significantly over about 30% of the relevant standard uncertainty, leading to correlation coefficients |r| greater than 0.1. The implementation includes a more robust differentiation algorithm than previously reported for spreadsheet use, and initial preparation of the spreadsheets has been automated. The principle is illustrated with a simple example.
Keywords: Measurement uncertainty; Correlation; Spreadsheet
Comparison of regression techniques for linear calibration by L. Brüggemann; P. Morgenstern; R. Wennrich (pp. 344-351).
A recently presented regression technique for linear calibration, which is based on a variance component model for univariate quantitative measurement data, is compared with the conventional and far spread regression techniques ordinary least squares regression and weighted least squares regression. The associated statistical models and estimations are represented. Its application is demonstrated at some practical examples. With consideration of special variation causes, like matrix influence or the influence of several operating conditions on the measurement response, it can be shown that the application of the variance component model is an advantage.
Keywords: Linear calibration; Regression techniques; Variance component model
Comparison of regression techniques for linear calibration by L. Brüggemann; P. Morgenstern; R. Wennrich (pp. 344-351).
A recently presented regression technique for linear calibration, which is based on a variance component model for univariate quantitative measurement data, is compared with the conventional and far spread regression techniques ordinary least squares regression and weighted least squares regression. The associated statistical models and estimations are represented. Its application is demonstrated at some practical examples. With consideration of special variation causes, like matrix influence or the influence of several operating conditions on the measurement response, it can be shown that the application of the variance component model is an advantage.
Keywords: Linear calibration; Regression techniques; Variance component model
The microporous structure of silver/silver chloride electrodes and the implications for Harned cell operation by Richard J. C. Brown; Martin J. T. Milton (pp. 352-355).
The stability of silver/silver chloride reference electrodes when moved between different electrolyte solutions is limited by the small amount of solution transferred. The time required for the Ag/AgCl electrode potential to stabilize has been shown to increase with electrode size in an empirical fashion. The results presented suggest the presence of a microporous structure in the electrodes that limits the rate at which traces of any previous solutions are diluted by any new solution environment. Operational implications for the stability and accuracy of the Harned Cell used as the primary standard for pH measurements and the certification of primary reference buffers are discussed.
Keywords: pH; Harned cell; Silver chloride electrodes
The microporous structure of silver/silver chloride electrodes and the implications for Harned cell operation by Richard J. C. Brown; Martin J. T. Milton (pp. 352-355).
The stability of silver/silver chloride reference electrodes when moved between different electrolyte solutions is limited by the small amount of solution transferred. The time required for the Ag/AgCl electrode potential to stabilize has been shown to increase with electrode size in an empirical fashion. The results presented suggest the presence of a microporous structure in the electrodes that limits the rate at which traces of any previous solutions are diluted by any new solution environment. Operational implications for the stability and accuracy of the Harned Cell used as the primary standard for pH measurements and the certification of primary reference buffers are discussed.
Keywords: pH; Harned cell; Silver chloride electrodes
EQUIP: a worldwide program to ensure the quality of urinary iodine procedures by Kathleen L. Caldwell; Amir Makhmudov; Robert L. Jones; Joseph G. Hollowell (pp. 356-361).
In 2001 the Centers for Disease Control and Prevention (CDC) established a program, Ensuring the Quality of Urinary Iodine Procedures (EQUIP); to assist laboratories around the world and assess the accuracy of their urinary iodine (UI). CDC designed EQUIP to issue unknown specimens to participating laboratories three times per year. Each laboratory was asked to analyze unknown samples in duplicate on three different days. During the first five rounds of EQUIP, 41 laboratories participated, measuring unknown samples and reporting their results to CDC. CDC used these results to prepare a statistical report for the laboratories. Feedback to the laboratories provided external confirmation regarding performance. As a group, laboratory performance improved; several laboratories made considerable improvement. Several laboratories that showed no improvement have ordered new equipment or are arranging for additional training. EQUIP is a key tool used to support laboratory quality assurance in an effort to eliminate iodine deficiency disorders (IDD) in the world.
Keywords: Urinary iodine; Iodine deficiency disorders; Laboratory testing; ICP-MS; Laboratory proficiency; Laboratory methods
EQUIP: a worldwide program to ensure the quality of urinary iodine procedures by Kathleen L. Caldwell; Amir Makhmudov; Robert L. Jones; Joseph G. Hollowell (pp. 356-361).
In 2001 the Centers for Disease Control and Prevention (CDC) established a program, Ensuring the Quality of Urinary Iodine Procedures (EQUIP); to assist laboratories around the world and assess the accuracy of their urinary iodine (UI). CDC designed EQUIP to issue unknown specimens to participating laboratories three times per year. Each laboratory was asked to analyze unknown samples in duplicate on three different days. During the first five rounds of EQUIP, 41 laboratories participated, measuring unknown samples and reporting their results to CDC. CDC used these results to prepare a statistical report for the laboratories. Feedback to the laboratories provided external confirmation regarding performance. As a group, laboratory performance improved; several laboratories made considerable improvement. Several laboratories that showed no improvement have ordered new equipment or are arranging for additional training. EQUIP is a key tool used to support laboratory quality assurance in an effort to eliminate iodine deficiency disorders (IDD) in the world.
Keywords: Urinary iodine; Iodine deficiency disorders; Laboratory testing; ICP-MS; Laboratory proficiency; Laboratory methods
An inter-laboratory comparison study for the determination of copper and lead from the wastewater of printed circuit board manufacturing industry in Pakistan by S. S. Tahir; Rauf Naseem; Anwar ul Haq; Khalid Saeed (pp. 362-368).
This inter-laboratory comparison study was arranged for 28 laboratories from different public and private sector organizations in Pakistan having wastewater testing capabilities aimed at improving the quality and comparability of test results. This national inter-laboratory study was started in December 2003 and completed in July 2004. Laboratories were invited to analyze the wastewater collected from printed circuit board (PCB) industry for lead and copper contamination. The samples fulfill the criteria for homogeneity and stability as done by the reference laboratory. The results obtained from participating laboratories were analyzed in terms of Hampel Test for outliers, while the performance evaluation of the participating laboratories was done on the basis of Z-score. An assigned value derived from the participant's results was compared with a reference value provided by a reference laboratory. Overall >50% of the participating laboratories have shown good performance in this PT-program
Keywords: Inter-laboratory comparison; PCB manufacturing industry; Copper; Lead; Outlier; Uncertainty; Pakistan
An inter-laboratory comparison study for the determination of copper and lead from the wastewater of printed circuit board manufacturing industry in Pakistan by S. S. Tahir; Rauf Naseem; Anwar ul Haq; Khalid Saeed (pp. 362-368).
This inter-laboratory comparison study was arranged for 28 laboratories from different public and private sector organizations in Pakistan having wastewater testing capabilities aimed at improving the quality and comparability of test results. This national inter-laboratory study was started in December 2003 and completed in July 2004. Laboratories were invited to analyze the wastewater collected from printed circuit board (PCB) industry for lead and copper contamination. The samples fulfill the criteria for homogeneity and stability as done by the reference laboratory. The results obtained from participating laboratories were analyzed in terms of Hampel Test for outliers, while the performance evaluation of the participating laboratories was done on the basis of Z-score. An assigned value derived from the participant's results was compared with a reference value provided by a reference laboratory. Overall >50% of the participating laboratories have shown good performance in this PT-program
Keywords: Inter-laboratory comparison; PCB manufacturing industry; Copper; Lead; Outlier; Uncertainty; Pakistan
ISO 17025 quality system in a university environment by Ako Rodima; Martin Vilbaste; Olev Saks; Erko Jakobson; Eve Koort; Viljar Pihl; Lilli Sooväli; Lauri Jalukse; Julia Traks; Kristina Virro; Heiki Annuk; Kristjan Aruoja; Aare Floren; Ene Indermitte; Monika Jürgenson; Paavo Kaleva; Kalle Kepler; Ivo Leito (pp. 369-372).
The experience of working under an ISO 17025 compliant quality system in a university environment is described in the example of the Testing Centre of University of Tartu. University-specific features of the quality system include that the Testing Centre acts as the “quality system server” for other units of the university and graduate students participate in the work carried out under the quality system. The benefits for the university and the graduate students are discussed. It is concluded that implementation of an ISO 17025 compatible quality system in a university is fully accomplishable and gives significant added value to the university by helping to destroy the ivory tower perception about universities and by introducing real-world flavour into the studies and broaden the minds (quality awareness) of the students.
Keywords: Quality system; Quality management; University; Graduate studies
ISO 17025 quality system in a university environment by Ako Rodima; Martin Vilbaste; Olev Saks; Erko Jakobson; Eve Koort; Viljar Pihl; Lilli Sooväli; Lauri Jalukse; Julia Traks; Kristina Virro; Heiki Annuk; Kristjan Aruoja; Aare Floren; Ene Indermitte; Monika Jürgenson; Paavo Kaleva; Kalle Kepler; Ivo Leito (pp. 369-372).
The experience of working under an ISO 17025 compliant quality system in a university environment is described in the example of the Testing Centre of University of Tartu. University-specific features of the quality system include that the Testing Centre acts as the “quality system server” for other units of the university and graduate students participate in the work carried out under the quality system. The benefits for the university and the graduate students are discussed. It is concluded that implementation of an ISO 17025 compatible quality system in a university is fully accomplishable and gives significant added value to the university by helping to destroy the ivory tower perception about universities and by introducing real-world flavour into the studies and broaden the minds (quality awareness) of the students.
Keywords: Quality system; Quality management; University; Graduate studies
A software package comparison for uncertainty measurement estimation according to GUM by J. M. Jurado; A. Alcázar (pp. 373-381).
Six commercial programs devoted to the estimation of measurement uncertainty were compared for feasibility in order to be applied in routine chemical analysis. The main features of each program were discussed. They were applied to two well-documented case studies. Several screen captures were considered for illustration.
Keywords: Measurement uncertainty; GUM approach; Monte-Carlo simulation
A software package comparison for uncertainty measurement estimation according to GUM by J. M. Jurado; A. Alcázar (pp. 373-381).
Six commercial programs devoted to the estimation of measurement uncertainty were compared for feasibility in order to be applied in routine chemical analysis. The main features of each program were discussed. They were applied to two well-documented case studies. Several screen captures were considered for illustration.
Keywords: Measurement uncertainty; GUM approach; Monte-Carlo simulation
Effect of moisture adsorption/desorption on external cylinder surfaces: influence on gravimetric preparation of reference gas mixtures by Nobuhiro Matsumoto; Takuro Watanabe; Kenji Kato (pp. 382-385).
There are many error sources in the preparation of primary reference gas mixtures by the gravimetric method. One of the error sources is the adsorption/desorption of moisture on the external gas cylinder surface. Variation of relative humidity in atomospheric air around the cylinder during the preparation process may cause an error in the mass measurement of the gas cylinder. Effect of the adsorption/desorption on the surface is dependent on the condition of the external cylinder surface. In this study, various types of cylinders are precisely weighed under different humidity conditions. Hairline finish and shot blast finish are preferable treatments for the external cylinder surface in our experiments. The use of cylinders with painted surface should be avoided as possible if the humidity control in the rooms is insufficient. Table 1 Tested cylinders with various finishes on external surfaces Type of finishes Features (a) Type A Paint coating Phthalic acid resin enamel was used as paint (b) Type B Paint coating scraped Paint of type A was scraped with an electronic sander (c) Type C Paint coating Epoxy resin was used as paint (d) Type D Shot blast finish Abrasives were sprayed against the external surface. The surface had roughness like coat of pome (e) Type E Hairline finish Surface was polished with sandstone or something similar. Many fine stripes on the surface and its surface had metallic luster
Keywords: Gas metrology; Reference gas mixtures; Gravimetric method; Adsorption/desorption on external cylinder surface
Effect of moisture adsorption/desorption on external cylinder surfaces: influence on gravimetric preparation of reference gas mixtures by Nobuhiro Matsumoto; Takuro Watanabe; Kenji Kato (pp. 382-385).
There are many error sources in the preparation of primary reference gas mixtures by the gravimetric method. One of the error sources is the adsorption/desorption of moisture on the external gas cylinder surface. Variation of relative humidity in atomospheric air around the cylinder during the preparation process may cause an error in the mass measurement of the gas cylinder. Effect of the adsorption/desorption on the surface is dependent on the condition of the external cylinder surface. In this study, various types of cylinders are precisely weighed under different humidity conditions. Hairline finish and shot blast finish are preferable treatments for the external cylinder surface in our experiments. The use of cylinders with painted surface should be avoided as possible if the humidity control in the rooms is insufficient. Table 1 Tested cylinders with various finishes on external surfaces Type of finishes Features (a) Type A Paint coating Phthalic acid resin enamel was used as paint (b) Type B Paint coating scraped Paint of type A was scraped with an electronic sander (c) Type C Paint coating Epoxy resin was used as paint (d) Type D Shot blast finish Abrasives were sprayed against the external surface. The surface had roughness like coat of pome (e) Type E Hairline finish Surface was polished with sandstone or something similar. Many fine stripes on the surface and its surface had metallic luster
Keywords: Gas metrology; Reference gas mixtures; Gravimetric method; Adsorption/desorption on external cylinder surface
Estimation of the uncertainty of mass measurements from in-house calibrated analytical balances by A. Gustavo González; M. Ángeles Herrador; Agustín G. Asuero (pp. 386-391).
The uncertainty evaluation of mass measurements when using “in-house” calibrated analytical balances is revisited according to the Guide to the expression of Uncertainty Measurement (GUM). The calibration of analytical balances is discussed according to the guidelines of several bodies such as ASTM, UKAS and DKD/PTB. The remainder components of uncertainty can be estimated from the balance data sheet specifications.
Keywords: Weighting uncertainty; Mass uncertainty; Balance calibration; Balance specifications
Estimation of the uncertainty of mass measurements from in-house calibrated analytical balances by A. Gustavo González; M. Ángeles Herrador; Agustín G. Asuero (pp. 386-391).
The uncertainty evaluation of mass measurements when using “in-house” calibrated analytical balances is revisited according to the Guide to the expression of Uncertainty Measurement (GUM). The calibration of analytical balances is discussed according to the guidelines of several bodies such as ASTM, UKAS and DKD/PTB. The remainder components of uncertainty can be estimated from the balance data sheet specifications.
Keywords: Weighting uncertainty; Mass uncertainty; Balance calibration; Balance specifications