Importance,Organization and Evaluation of Interlaboratory Tests

The importance of "precise"test values and their verification is growing in every industry throughout the world. Interlaboratory studies constitute a basis for this.The high expenses and mathematical work required to carry out proper interlaboratory studies are frequently considered reasons not to conduct such studies. This makes it all the more important to emphasize the various advantages of an accurate interlaboratory study. In addition to providing precision data for the test method,it is also possible to carry out laboratory evaluations,which is important for accredited test laboratories. Furthermore,existing test methods can be optimized,reference material can be obtained,and test methods can be compared. Optimized test instructions can also be generated using the findings and precision data. These advantages will be described in detail by means of examples below.     

Testing colour fading of cotton fabrics by activated oxygen bleach-ontaining detergent an interlaboratory trial

A single diagnostic wash test to identify coloured cotton fabrics susceptible to activated oxygen bleach was subjected to an interlaboratory trial (ring test). The results from the trial are described and a procedure developed for use as a British Standard is outlined.     

稳健统计技术和图示技术在分析评定白酒总酯检测能力的应用

利用稳健统计技术对白酒总酯的能力比对数据进行了统计分析,计算实验室间Z比分数和实验室内Z比分数,结合图示方法评价了实验室的结果并分析出实验室误差种类;结合实验过程,分析了误差的主要来源,为改进实验室质量提供了依据。     

Interlaboratory Analyses of Carbonaceous Aerosol Samples

The California Air Resources Board (ARB) sponsored a 9-day field study for the intercomparison of methods for the measurement of carbonaceous aerosol species on the campus of Citrus College, Claremont, CA, in August 1986. As the quality assurance manager for the 1986 ARB-sponsored Carbonaceous Aerosol Methods Comparison Study, Environmental Monitoring and Services, Inc. distributed a set of “reference” aerosol samples to 13 laboratories for a comparison of different analytical methods for carbon. This paper describes the different reference samples used in the interlaboratory study and the analytical methods used by the different groups for their analysis. The analytical results from all participating laboratories are summarized in this paper. In general, the agreement between all laboratories for total carbon was within 20% for all samples. However, there were large interlaboratory differences in the organic carbon/ elemental carbon ratio for all samples, with the largest differences occurring of the automotive and woodsmoke dominated reference samples.     

Interlaboratory Tests on Polymers by Differential Scanning Calorimetry (DSC): Determination of Glass Transition Temperature (Tg)

The present report presents results obtained from an interlaboratory test. 28 participants, mainly from industry and research institutes, measured glass transition temperatures (T_g) by differential scanning calorimetry (DSC) on four different polymers. The materials used were poly(methyl methacrylate) (PMMA), polycarbonate (PC), polysulfone (PSU) and amorphous polyamide (PA 6I/6T). The measured data were collected by EMPA and were evaluated using a robust statistical method. Repeatability and reproducibility data were of special interest. The repeatability limit (r) of glass transition temperatures measured according to DIN 53765 was found in the region of 1–2°C, and the reproducibility limit (R) was around 3–4°C. In addition to the DIN standard, the set of interlaboratory test data was evaluated and considered according to some different approaches and was correlated with data from other EMPA interlaboratory tests performed previously. It was shown that the investigated statistical parameter was always in a similar dimension. The data of the PA sample were found to be an exception. Due to the hygroscopic character of polyamide, the r and R values increase sharply, to an almost three times higher reproducibility limit. Overall, the evaluated data can be used to estimate the results of own and external T_g measurements and their compatibility. The report should therefore support daily work in analytical laboratories where glass transition temperatures are measured by DSC.     

Determination of fatty acid composition by gas chromatography: II. Analysis with use of flame ionization detector

In this study known mixtures of four or five fatty acid methyl esters were analyzed collaboratively by gas chromatography with flame ionization detectors. The experimental data was treated statistically to examine inter- and intralaboratory scattering. More-over the effect of the use of correction factors was investigated. Even if only the specific analytical values that scattered a little were chosen, the averages of such values did not always approach the actual values. In some laboratories a sort of regularity was observed in the deviation of analytical values from real values throughout the analyses of four samples. The application of correction factors to the analytical values obtained by these laboratories resulted in a considerable decrease of interlaboratory scattering and deviation from the real values. When a constant amount of sample was injected, intralaboratory scattering was decreased, whereas interlaboratory scattering was not. Injection of large sample sizes caused deviation. From this collaborative study it was recommended that 0.5–1.0 μl of 20% solution be injected. Presented at the JOCS-AOCS Joint Meeting, Los Angeles, April 1972.     

Publication Sponsored by the Society's Fastness Tests Co–ordinating Committee – XLIV

Specific application of BSI recommendations for testing new test methods is illustrated quantitatively for an interlaboratory trial of a new colour–fastness test (colour fastness to chlorination: sodium dichloroiso–cyanurate). Statistical analyses of the results quantify repeatabilities and reproducibilities.     

Determination of low boiling solvents in liquid formulations by gas chromatography [H‐VIII 2a (Status: 01.10.2003)]

The following method was tested by the “Gemeinschaftsausschuss für die Analytik von Tensiden (GAT)” in an interlaboratory test. GAT puts the method up for discussion and invites readers to make comments to the referees above. Afterwards it is intended to include this method in Section H – Surfactants, Chapter VIII of the DGF Standard Methods     

Publication Sponsored by the Society's Fastness Tests Co-ordinating Committee-52 Colour Fastness to Chlorinated Water (Swimming Bath Water)

Results obtained using the current standard test (BS 1006-.E03:1978) do not correspond adequately with the performance of representative dyeings from current ranges of fabrics used in chlorinated swimming pools. A revised test method is defined. It has been subjected to interlaboratory evaluation, to assess repeatability and reproducibility and compared with results from swimming pool trials. It has been shown to be satisfactory in both respects.     

火花点燃式发动机压缩比与数字计数器读数的校正关系

采用压缩比与数字计数器的对应检索校正关系来评定检查火花点燃式发动机的机械状况。根据沿海不同地区室内室间实验室的对比与协调试验计算分析，所采用的检索法达到美国沃克夏机器制造厂规定的ASTM精度。本文提出的检索法具有快速、简捷和准确等特点，可适用于沿海地区火花点燃式发动机的机械设备状况校准试验。     

The roles of standard cigarettes in assuring the ignition resistance of soft furnishings

Regulations for cigarette ignition resistance (CIR) of soft furnishings (beds and upholstered furniture) and less fire‐prone cigarettes have contributed substantially to the decrease in losses from cigarette‐initiated fires over time. Two standard reference cigarettes play key roles in mitigating these losses and in sustaining the effectiveness of the fire safety regulations as exogenous changes occur. SRM 1082 provides a uniform, durable supply of cigarettes for use in ASTM E2187 that assures manufacturers and regulators of compliance with regulations for reduced ignition propensity cigarettes; enables quality control of cigarette fire test performance; enables assurance of uniform interlaboratory test results; obviates effects on fire safety as tobacco crops and smokers change over time; and, when the original ASTM E2187 substrate material was no longer available, enabled adding a new, equivalent substrate. SRM 1196 provides a uniform, durable supply of cigarettes for assurance of consistent interlaboratory evaluation of the ignition resistance of soft furnishings using the mandated test methods; obviates possible unknown changes in soft furnishings' CIR due to the evolving ignition strength of the original test cigarette over time; and provided a test cigarette that was stronger than most cigarettes being smoked after manufacture of the original commercial test cigarette ceased.     

An interlaboratory study of test methods

Conclusions Our aim has been to construct a simple method of scoring consistent with the objectives of the study and to present the results in a manner that does not require too much statistical sophistication. However, if realistic estimates of the precision of test methods are to be obtained, the interlaboratory tests must be more thoughtfully designed and the statistical analysis will tend to be somewhat more complicated as in the components of variance analysis we have presented.     

Solid fat content in fats and oils ‐ determination by pulsed nuclear magnetic resonance spectroscopy [C‐IV 3g (2003)]

The “Joint Committee for the Analysis of Fats, Oils, Fatty products, Related Products and Raw Materials (GA FETT )” has developed the following method for the determination of the Solid Fat Content (SFC) in fats and oils. It is intended to include this method in Section C, Chapter IV of the German Standard Methods. The method reflexes the need of the fats and oils industry to get fast results and was tested in an interlaboratory test with 16 laboratories from 6 European countries.     

Sinn und Zweck von Laborvergleichsuntersuchungen

Meaning and Purpose of Proficiency Testings The final results of the first proficiency testing of analytical laboratories organized by the German Society for Fat Science (DGF) demonstrate that interlaboratory tests are necessary to control the quality assurance system of a laboratory. Because of its competence and independence DGF is predominated to organize and execute such tests for the certification of a laboratory without any commercial interests. Based on the international harmonized protocol for proficiency testing a new evaluation system was developed which allows to compare the efficiencies among the laboratories according to the analytical practice.     

Interlaboratory Test of Exhaust PM Using ELPI

Abstract

The Particulate Measurement Programme (PMP) works on the development of an improved method for the exhaust particulate matter (PM) measurement, which can include, if feasible and necessary, the measurement of particle number. The French PMP subgroup, composed of IFP, PSA Peugeot-Citroën, Renault, and UTAC, has defined a measurement protocol based on electrical low-pressure impactor (ELPI) and conducted an interlaboratory test to evaluate its performances. The technical program was based on tests carried out on three Euro3 passenger cars (one gasoline operating under stoichiometric conditions, one Diesel, and one Diesel equipped with a diesel particulate filter (DPF)) that were tested on the New European Driving Cycle (NEDC). The regulated pollutants are also measured, as indicators of test repeatability and good working conditions. The interlaboratory reproducibility value of the tunnel background tests is quite high (337%) due to low particle numbers. The repeatability values increase at low particle numbers independently of the vehicle used. On the NEDC, the reproducibility of total particle number is 59, 47, and 131% for the gasoline, Diesel, and DPF-equipped Diesel vehicles, respectively (compare to 67, 29, and 164% for PM collected on filters). These results show that the protocol used in this study allows a reliable measurement of exhaust particle number in the case of vehicles emitting at least two orders of magnitude more than the tunnel background. In the other cases, the measurement variability is too high, especially for regulatory purposes, without taking into account other metrological aspects, such as calibration.     

连续流动分析法比对实验能力验证样品的均匀性和稳定性检验

通过单因子方差分析法检验连续流动分析法比对实验验证样品的均匀性,F计算相似文献   

Measurement of Luminance Factor

Luminance factor of a diffusing material is defined as the ratio of the luminance of the surface of the material to that of a perfect (Lambertian) diffuser under specified conditions of illuminance and angle of view. Measurement of this quantity has always been rather difficult, involving visual photometric measurements at widely different levels of illuminance. A physical method of measuring luminance factor is described which has given more repeatable results and better interlaboratory agreement than the former visual method.     

Fracture toughness testing for advanced technical ceramics: internationally agreed good practice

Abstract

The development of robust methods for determining fracture toughness and for interlaboratory assessment of results is discussed with respect to procedural standardisation. Acceptable methods are based on meeting several criteria, including ease and cost-effectiveness of testpiece manufacture, the method of introducing a sharp precrack and the acceptability of appropriate fracture toughness analysis. The four simplest methods meeting these criteria are reviewed in detail, together with information on their reproducibility gathered during international round robin exercises. Not all these methods are effective on all materials, and users need to be aware of their limitations. Details of calibration equations and some experimental nuances are given.     

Publication Sponsored by the Society's Fastness Tests Co–ordinating Committee –XLVI

The precision of Grey–Scale assessment of change in colour is estimated. Allowance was made for any interlaboratory differences, prior to assessment, in carrying out a colour–fastness test, using the prescribed test method, to obtain the specimens. The results show how the assessment precision depends on the Grey–Scale rating. The practical laboratory component of obtaining the tested specimens almost always has better precision than the subsequent assessment. The particular test method used to obtain the specimens can therefore be regarded as having satisfactory precision in practical application. Taking the mean of three assessors results in better precision than that from a single assessment. Assessment precision appears consistent when compared with appropriately transformed older data.     

Improving interalboratory precision for surface area

Poor interlaboratory precision for the determination of nitrogen adsorption specific area initiated a study of the parameters involved. Degassing conditions were standarized following the investigation of temperature- time relationships of various alumina types which may be present in smelter-grade alumina. Complete isotherms were obtained, single versus triple points were compared, and attempts were made to use carbon as a standard. A standard degassing procedure has resulted in improved precision for two laboratories having different equipment. There are some unanswered questions regarding desensitization of surface during analysis and the applicability of the BET equation.