for Journals by Title or ISSN for Articles by Keywords help
 Subjects -> CHEMISTRY (Total: 841 journals)     - ANALYTICAL CHEMISTRY (50 journals)    - CHEMISTRY (593 journals)    - CRYSTALLOGRAPHY (21 journals)    - ELECTROCHEMISTRY (25 journals)    - INORGANIC CHEMISTRY (41 journals)    - ORGANIC CHEMISTRY (44 journals)    - PHYSICAL CHEMISTRY (67 journals) CHEMISTRY (593 journals)                  1 2 3 | Last

1 2 3 | Last

 Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement   [SJR: 0.378]   [H-I: 30]   [26 followers]  Follow         Hybrid journal (It can contain Open Access articles)    ISSN (Print) 0949-1775 - ISSN (Online) 1432-0517    Published by Springer-Verlag  [2353 journals]
• Full method validation in clinical chemistry
• Authors: Elvar Theodorsson; Bertil Magnusson
Pages: 235 - 246
Abstract: Abstract Clinical chemistry is subject to the same principles and standards used in all branches of metrology in chemistry for validation of measurement methods. The use of measuring systems in clinical chemistry is, however, of exceptionally high volume, diverse and involves many laboratories and systems. Samples for measuring the same measurand from a certain patient are likely to encounter several measuring systems over time in the process of diagnosis and treatment of his/her diseases. Several challenges regarding method validation across several laboratories are therefore evident, but rarely addressed in current standards and accreditation practices. The purpose of this is paper to address some of these challenges, making a case that appropriate conventional method validation performed by the manufacturers fulfils only a part of the investigation needed to show that they are fit for purpose in different healthcare circumstances. Method validation across several laboratories using verified commercially available measuring systems can only be performed by the laboratories—users themselves in their own circumstances, and need to be emphasised more by the laboratories themselves and accreditation authorities alike.
PubDate: 2017-10-01
DOI: 10.1007/s00769-017-1275-7
Issue No: Vol. 22, No. 5 (2017)

• Method validation in analytical sciences: discussions on current practice
and future challenges
• Authors: Vicki Barwick; Stephen L. R. Ellison; Elin Gjengedal; Bertil Magnusson; Olivier Molinier; Marina Patriarca; Lorens Sibbesen; Nicole Vanlaethem; Isabelle Vercruysse
Pages: 253 - 263
Abstract: Abstract Eurachem held a workshop on method validation in analytical sciences in Gent, Belgium, on 9–10 May 2016. A summary of the working group discussions is provided here. The discussions covered a range of issues concerned with current practice and future challenges in method validation, i.e. setting requirements for a method to be validated; planning validation studies; validation of qualitative and semi-quantitative methods; validation of multi-parameter methods; determination of trueness/bias; assessment of working range; validation in microbiology; and method validation under flexible scope of accreditation. Delegates (129) from 24 different countries and from different backgrounds, e.g. from both public and private laboratories, laboratory associations, accreditation bodies and universities, attended the working groups, thus providing opportunities to collect a variety of views and experiences as well as to identify potential gaps in current guidance and regulations. While the practicalities of assessing method performance characteristics are generally well understood, the issue of setting requirements for those characteristics beforehand is less straightforward. Although a number of documents addressing the principles of method validation are available, guidance on dealing with more complex and ‘non-ideal’ situations, as well as examples of good practice, would be welcomed and greater harmonisation of approaches was deemed necessary. There remains a need for guidance on both the concepts that apply to ‘qualitative’ or ‘nominal’ test methods and on the practical implementation of validation studies in such cases.
PubDate: 2017-10-01
DOI: 10.1007/s00769-017-1286-4
Issue No: Vol. 22, No. 5 (2017)

• Congress, conferences, workshops and courses
• Pages: 233 - 233
PubDate: 2017-08-01
DOI: 10.1007/s00769-017-1278-4
Issue No: Vol. 22, No. 4 (2017)

• Determination and quality evaluation of six components in Zhou’s
Prescription through quantitative analysis of multi-components by single
marker
• Authors: Cuicui Gu; Fang Wu; Yanmei Cao; Lian Yin; Xu Zhang; Lihong Ye; Zhongying Zhou
Abstract: Abstract Zhou’s Prescription is a compound prescription with traditional Chinese medicine, which is composed of 13 kinds of herbs and has been used to treat lung cancer in clinical practice for many years in China. Quantitative analysis of multi-components with single marker (QAMS) was used for the first time to analyze Zhou’s Prescription for the mass contents of six active ingredients, and chemometric methods were applied to evaluate its quality. Quercetin was selected as the internal standard serving as basis for relative correction factors (RCFs) determined using different HPLC instruments and columns. The contents of the active ingredients hydroxysafflor yellow A, rutin, hyperoside, isoquercitrin and quercitrin were calculated applying the RCFs. The stability and accuracy of QAMS were tested and verified by an external standard method (ESM). The accuracy was between 94.5 % and 100.4 % demonstrating the consistency of QAMS and ESM. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) were applied to classify 21 batches of Zhou’s Prescription which were composed with supplies of the 13 herbs from different harvests at different producing regions. Among the 21 batches, a significant difference between the contents of the active ingredients was found which can be distinguished by chemometric methods. QAMS proved to be a promising and accurate method to quantify the active ingredients in Zhou’s Prescription also when resources of reference substances are limited. Moreover, the quality of Zhou’s Prescription is determined by the content of active ingredients scaled by HPLC. The method is based on QAMS combined with HCA and PCA to comprehensively evaluate the quality of Zhou’s Prescription composed of herbs of different sources.
PubDate: 2017-09-18
DOI: 10.1007/s00769-017-1287-3

• Congress, conferences, workshops and courses
• PubDate: 2017-09-06
DOI: 10.1007/s00769-017-1289-1

• Investigation of homogeneity and stability of items for proficiency
testing of solid recovered fuels (SRF) analysis
• Authors: Barbara Jagustyn; Agnieszka Plis; Mariusz Mastalerz; Joanna Hrabak; Marek Ściążko
Abstract: Abstract Solid recovered fuel (SRF) is made of waste and used as a substitute for fossil fuel. Physical and chemical analyses are needed to evaluate the usefulness of the waste in power and heat generation. This paper reports the assessment of homogeneity and stability of laboratory and analytical samples, with different particle size, obtained from three materials of different composition. The components of first material included soft plastics, plastics foam, composite packaging with the content of aluminum foil, cigarette filters, paper, cardboard, textiles, wood, and cotton. The second material mainly contained soft plastics and the needles from artificial Christmas trees, a lower amount of artificial leather, and aluminum foil. The third material was mainly composed of soft plastics and paper. The parameter used in the homogeneity and stability assessment was ash content on a dry basis. The homogeneity and stability assessment was carried out according to ISO 13528:2015; on the basis of a standard deviation for proficiency assessment calculated using the repeatability and reproducibility standard deviations from a previous collaborative study of precision of a measurement method. The homogeneity assessment was carried out using laboratory and analytical samples of SRF. Based on measurements of ash content, laboratory samples as the test items OB1 with a particle size below 4 mm were not sufficiently homogeneous, regardless of the SRF type, among our samples those with the largest particles. The analytical samples as the test items OB2 with a particle size below 1 mm and OB3 with a particle size below 0.5 mm were sufficiently homogeneous. For these samples, the stability assessment was carried out and studied samples were stable. The homogeneity and stability of SRF material were associated not so much with the grinding but the composition of the material.
PubDate: 2017-08-22
DOI: 10.1007/s00769-017-1283-7

• Analysis of findings throughout the cycles of accreditation of veterinary
diagnostic testing laboratories for diseases transmitted by products of
animal origin
• Authors: Patricia Weigert de Camargo; Elmiro Rosendo do Nascimento; Maria Helena Cosendey de Aquino
Abstract: Abstract This work describes the frequency of findings registered in the assessment reports of 23 Brazilian animal health laboratories from 2008 to 2016. The study was conducted in consideration of the ISO/IEC 17025 requirements and normative documents issued by the Brazilian Accreditation Body [General Coordination for Accreditation (Cgcre)]. The general performance of these laboratories throughout the evaluation cycles was investigated. The types and number of findings reported in the assessments of these laboratories were analyzed according to the management and technical requirements of ISO/IEC 17025 and Cgcre’s normative documents. The laboratories’ performance was compared in consideration of the number of findings reported in the first and last assessments of each laboratory investigated.
PubDate: 2017-08-18
DOI: 10.1007/s00769-017-1284-6

• Are the present measurement standards still valid after SI
redefinition'
• Authors: Franco Pavese
Abstract: Abstract The SI revision potentially places some basic concerns to all users, one being the validity of their present standards under the new definition. The paper compares what is spelled out in the new SI Brochure draft to what should be specified for practical implementation. The result of the analysis is uncertain for some level of implementation and some standards, with, on the other hand, some positive aspects also illustrated in the paper, not always found explicit in the formal texts.
PubDate: 2017-08-16
DOI: 10.1007/s00769-017-1282-8

• National interlaboratory comparisons in the field of breath alcohol
analyzers calibration, performed in Poland, 2014–2016
• Authors: Piotr Janko; Robert Kordulasiński; Jolanta Wasilewska; Elżbieta Lenard
Abstract: Abstract Proficiency testing (PT) and interlaboratory comparisons (ILC) are basic tools of external quality assurance in testing and calibration laboratories. Seeking to meet the needs and expectations of all stakeholders, the Central Office of Measures (GUM) provides ILC in the field of calibration of breath alcohol analyzers. This article describes a series of twelve bilateral ILCs conducted sequentially from December 2014 until July 2016. Eleven laboratories, accredited or in the process of preparation for accreditation, participated in these comparisons. Comparisons encompassed calibration of the same Intox II EC/IR analyzer at four test points: 0.10 mg/L, 0.25 mg/L, 0.41 mg/L, 1.52 mg/L. The results of participant performance evaluation, the results of the density measurements of participants’ liquid ethanol standards and the results of correlation analysis at four calibration points are presented. Nine out of eleven participants obtained all satisfactory results. One of the remaining laboratories confirmed the effectiveness of implemented remedial actions by successful participation in repeated ILC. Laboratories with satisfactory performance confirmed the declared uncertainty.
PubDate: 2017-08-09
DOI: 10.1007/s00769-017-1280-x

• Method validation for determination of amino acids in feed by UPLC
• Authors: Katarzyna Szkudzińska; Ilona Smutniak; Jolanta Rubaj; Waldemar Korol; Grażyna Bielecka
Abstract: Abstract The paper presents results of validation of an analytical procedure based on ultra-performance liquid chromatography technique (UPLC) for determination of 17 amino acids in different feeds. The following performance characteristics were determined for the investigated feeds: relative standard deviations of repeatability and intermediate precisions ranged from 0.4 % to 4.6 %, and from 0.8 % to 7.9 %, respectively; recovery rates ranged from 87 % to 104 %, and limit of detection was from 0.06 g kg−1 (methionine) to 0.72 g kg−1 (glutamic acid). Two approaches were used to estimate measurement uncertainty giving values in a range of 5.1 % to 5.5 %. These performance characteristics are in agreement with the values reported in Commission Regulation (EU) No 152/2009 for the ion exchange chromatography with spectrophotometric detection.
PubDate: 2017-08-01
DOI: 10.1007/s00769-017-1281-9

• Development of primary standard gas mixtures containing 10 µmol/mol
oxygen in nitrogen with verification by a two-oven GC-TCD system for
effective separation of oxygen from argon in presence of plenty of
nitrogen
• Authors: Takuya Shimosaka
Abstract: Abstract Primary standard gas mixtures (PSMs) containing 10 µmol/mol oxygen in nitrogen were prepared in aluminum alloy cylinders from pure nitrogen and oxygen gases according to ISO 6142-1. We developed a system consisting of a gas chromatograph with a thermal conductivity detector (GC-TCD) and two ovens to verify precisely the amount-of-substance fraction of oxygen in the PSMs at a level of 10 µmol/mol. As pure nitrogen gas usually contains argon as an impurity, it is necessary to separate the oxygen peak from the argon peak in order to verify the amount-of-substance fraction of oxygen in the PSMs. Although the use of packed columns is essential in order to achieve high precision using a GC-TCD system, it is notoriously difficult to separate oxygen and argon by this method. To overcome this problem, we used two gas chromatograph ovens: The first oven separates oxygen and argon from the nitrogen, whereas the second oven—held at −15 °C or below—separates oxygen and argon. The two-oven GC-TCD system was able to achieve good resolution between the oxygen and argon peaks. The relative uncertainty in the determination of the oxygen fraction obtained using this system was 0.35 %. In order to avoid adsorption of oxygen onto the inner surface of the aluminum cylinder, we pretreated each cylinder by filling it with a standard gas mixture of oxygen in nitrogen at an oxygen partial pressure similar to that of the PSMs. The cylinders were then evacuated and used for the preparation of the target PSMs. From long-term monitoring using the GC-TCD system, we found the PSMs containing 10 µmol/mol oxygen in nitrogen to be stable for at least 30 months. The expanded combined uncertainties for the PSMs (k = 2) were found to be 0.026 µmol/mol to 0.036 µmol/mol, according to ISO 6142-1.
PubDate: 2017-07-21
DOI: 10.1007/s00769-017-1279-3

• G. Férard, R. Dybkaer and X. Fuentes-Arderiu: Compendium of terminology
and nomenclature of properties in clinical laboratory sciences,
recommendations 2016 (Silver Book, 2nd ed.)
• Authors: David B. Hibbert
PubDate: 2017-07-12
DOI: 10.1007/s00769-017-1277-5

• Uncertainty evaluation for the determination of the dissolved fraction of
sulpiride content in tablets
• Authors: Biying Du
Abstract: Abstract The aim of this work was to establish a mathematical model to identify the main source of measurement uncertainty, quantify each uncertainty component, and calculate the combined and expanded uncertainties for determination of the fraction of sulpiride dissolved from tablets by UV spectrophotometry. The uncertainties on the absorbance (sample and standard), volumetric flasks and volumetric pipettes have important influence on the overall uncertainty. The average sulpiride fraction released from six tablets was 75.5 %, with an expanded uncertainty of 3.7 % (k = 2). Uncertainty is a relevant tool in assessment of compliance or non-compliance of in-process and final pharmaceutical products. Evaluation of the uncertainty of the dissolution measurement contributes to scientific explanation and interpretation of testing data, and ensures the results to be more accurate, impartial and convincing when testing a sample against specification or legislation.
PubDate: 2017-06-29
DOI: 10.1007/s00769-017-1273-9

• A statistical procedure for the assessment of bias in analytical methods
using conditional probabilities
• Authors: Robert B. Frenkel; Ian Farrance
Abstract: Abstract A new approach is described for the simultaneous treatment of bias and imprecision in clinical chemistry. The approach makes use of the general law of conditional probabilities. The result is a density distribution of the measurand that incorporates both imprecision and bias and avoids the contentious linear combination of these quantities as a ‘total error’. This leads naturally to a figure-of-merit in proficiency testing or method comparison that has intuitive visual appeal. We also discuss an established figure-of-merit in proficiency testing, namely the E n number.
PubDate: 2017-06-29
DOI: 10.1007/s00769-017-1274-8

• Development of milk powder reference material and its use for evaluation
of laboratory performance on analysis of mandatory nutrients for nutrition
labelling in Thailand
• Authors: Kunchit Judprasong; Prapasri Puwastien; Jutharat Supanuwat; Sitima Jittinandana; Naruemol Pinprapai
Abstract: Abstract This study investigated the laboratory performance on the analyses of mandatory nutrients for nutrition labelling in Thailand and aimed to upgrade the proficiency test (PT) material into a reference material (RM). This milk powder with sufficient homogeneity and multiple nutrient compositions provided an acceptable PT material. Twenty ISO 17025 accredited laboratories participated in this study, and analytical performance was investigated using ISO 17043 and ISO 13528 standards. Satisfactory performance ( z ≤ 2, for both within- and between-laboratory variations) was found among participating laboratories on the analyses of total fat, saturated fat, cholesterol, protein, sugar, sodium, vitamin B1, vitamin B2, calcium, iron, moisture, and ash. The values of these nutrients (mean and standard deviation) were applied to upgrade the PT material to be used as a reference material. For a trial, moisture, vitamin B1, and vitamin B2 were selected as three representative nutrients to develop reference values as mean and uncertainty following ISO Guides 34 and 35 for RM production. The mean of moisture, vitamin B1, and vitamin B2 values of 2.34 g/(100 g), 0.64 mg/(100 g), and 0.78 mg/(100 g) were obtained with the relative expanded uncertainty of 12.2 %, 12.7 %, and 9.7 %, respectively. The developed RM can be used as quality control sample or as PT material with reference nutrient values among the laboratories in Thailand.
PubDate: 2017-05-26
DOI: 10.1007/s00769-017-1269-5

• Evolution of quality on pharmaceutical design: regulatory requirement?
• Authors: AnaCerúlia Moraes doCarmo; Marcilio S. S. Cunha-Filho; Guilherme Martins Gelfuso; Tais Gratieri
Abstract: Abstract Quality by design (QbD) concept was first outlined by quality pioneer Joseph M. Juran, who believed quality could be designed into a product, preventing, therefore, most quality problems, normally related to the way quality was planned. This concept, as others related to quality conception and management, has already been applied by other industries, as automotive, and later introduced to pharmaceutical industry through US Food and Drug Administration and The International Council on Harmonization of Technical Requirements for Medicinal Products for Human Use guidelines. Brazil mostly applies statistical quality control and still does not have specific regulations regarding QbD, neither other countries in Latin America. Thus, the current stage of pharmaceutical quality regulation in Latin America must be understood to implement better strategies that can positively affect the development of drug products to reach advanced levels of quality. This article reviews aspects related to quality of pharmaceutics and assesses data to analyze whether Brazilian pharmaceutical industry can adapt to this scenario as a pilot for other South American countries.
PubDate: 2017-05-26
DOI: 10.1007/s00769-017-1270-z

• Combined uncertainty factor for sampling and analysis
• Authors: Michael H. Ramsey; Stephen L. R. Ellison
Abstract: Abstract Measurement uncertainty that arises from primary sampling can be expressed as an uncertainty factor, which recognises its sometimes approximately log-normal probability distribution. By contrast, uncertainty arising from chemical analysis is usually expressed as relative uncertainty, based upon the assumptions of its approximately normal distribution. A new method is proposed that enables uncertainty from these two sources, expressed in these different ways, to be combined to produce an estimate of the total combined uncertainty of the measurement values that result when the measurement process is considered as a whole.
PubDate: 2017-05-26
DOI: 10.1007/s00769-017-1271-y

• Identifying the critical cut-points of a quality control process for
serological assays: results from parametric and semiparametric regression
models
• Authors: Handan Wand; Wayne Dimech; Robert Freame; Kathy Smeh
Abstract: Abstract Quality control programs rely on continuous monitoring which may generate large volume of complex data. Assessing the precision of a biological assay using quality control processes is essential to evaluate the daily variations in a testing system. Variation can be introduced by reagents, instruments and operators, as well as biological changes in the populations screened. We have proposed a statistical analysis framework which combines novel statistical analysis and visualization techniques to determine the functional relationship between the quality control and blood donor’s negative results. Flexible semiparametric regression techniques were used to determine the functional relationships between blood donor’s hepatitis B surface antigen and anti-HIV test results and the reactivity of quality control samples over a period of 9 months. We demonstrated that the use of semiparametric regression models in conjunction with the probabilistic approaches may bring comprehensive insight into understanding the significant temporal features of the data and its impact on patient’s test results. In the absence of clinically relevant cut-point(s), data-driven methodologies, such as the one described in this study may potentially have significant benefits and widespread applications.
PubDate: 2017-05-19
DOI: 10.1007/s00769-017-1265-9

• Establishment of an analytical method for accurate purity evaluations of
acylcarnitines by using quantitative 1 H NMR spectroscopy
• Authors: Naoki Saito; Takeshi Saito; Taichi Yamazaki; Yoshinori Fujimine; Toshihide Ihara
Abstract: Abstract Recently, it has become possible to examine metabolism abnormalities by detecting increases in specific acylcarnitines in blood tests of newborn babies using tandem mass spectrometer. However, acylcarnitine standard solutions with metrological traceability to the International System of Units (SI) for accurate calibration of tandem mass spectrometer are not yet available worldwide. In this study, we examined a quantitative 1H NMR procedure for obtaining accurate and SI-traceable purity evaluations of acylcarnitines having different numbers of carbon atoms as each raw material for their standard solutions. In particular, the solvent composition and measurement temperature were optimized to reduce the influence of water signal overlapping on analyte signals. It was found that, when the signal of that 1H which directly bound to the asymmetric carbon of the acylcarnitine is the target signal, it was possible to reduce overlapping of the water signal on the target signal by using deuterium oxide as a solvent. On the other hand, in the case of an acylcarnitine that was poorly soluble in deuterium oxide, it was possible to reduce overlapping of the water signal on the target signal by adding an appropriate amount of deuterium oxide to methanol-d 4 in which the acylcarnitine had high solubility. At this time, the optimum mixing volume ratio of methanol-d 4/deuterium would be 80:20. The overlapping of the water signal could be also reduced when the measurement temperature was 15 °C to 40 °C. When the measurement temperature was an around room temperature (in this study, 25 °C), fine shimming could be performed easily. Therefore, the optimum temperature would be 25 °C, because fine shimming was essential to quantify any signal area accurately. Finally, this study confirmed that accurate values with SI traceability could be obtained at about 1 % or less expanded uncertainty for five kinds of acylcarnitines.
PubDate: 2017-04-29
DOI: 10.1007/s00769-017-1263-y

• Note on the correction of negative measured values if the measurand is
positive or 0 with known probability
• Authors: Peter-Th. Wilrich
Abstract: Abstract Often the amount of a substance or the activity of radionuclides in a sample is measured indirectly as the difference between signal and noise, i.e. the difference between the measured value obtained at the sample and that obtained at a sample not containing the substance or the radionuclides (blank sample). The difference can be negative, especially if the concentration or the activity is low. Since a negative measurement result for a nonnegative measurand does not make sense, measured values must be corrected to nonnegative measurement results. We deal with the situation in which it is known that the measurand is 0 with a probability $$p_0$$ that is a priori known, and that the standard deviation $$\sigma$$ of the measurement is known. For this case Korun, Vodenik and Zorko extend an earlier paper by Korun and Zorko and derive the mean of the posterior distribution as a Bayesian estimator of the measurand. We offer an estimator that is based on the posterior probability $$\hat{p}_0$$ of the measurand being 0. If $$\hat{p}_0 > 1 - \hat{p}_0$$ it is 0 and otherwise the mode of the posterior distribution. This estimate is easier to calculate and less biased than that of Korun et al.
PubDate: 2017-04-26
DOI: 10.1007/s00769-017-1264-x

JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327

Home (Search)
Subjects A-Z
Publishers A-Z
Customise
APIs