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 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  [2329 journals]
• Congress, conferences, workshops and courses
• Pages: 169 - 170
PubDate: 2017-06-01
DOI: 10.1007/s00769-017-1267-7
Issue No: Vol. 22, No. 3 (2017)

• Congress, conferences, workshops and courses
• Pages: 109 - 109
PubDate: 2017-04-01
DOI: 10.1007/s00769-017-1259-7
Issue No: Vol. 22, No. 2 (2017)

• 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

• European analytical column number 45
• Authors: Wolfgang Buchberger; Slavica Razic
PubDate: 2017-04-28
DOI: 10.1007/s00769-017-1266-8

• 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

• Do accredited laboratories perform better in proficiency testing than
non-accredited laboratories?
• Authors: Ken Middlebrook
Abstract: Abstract The CALA proficiency testing programme has been in operation since 1991. As CALA is also an accreditation body, every result reported as part of the CALA PT schemes is identified as being from a CALA accredited laboratory or not from a CALA accredited laboratory. For this examination, a data set is a group of analytical results for a single measurand, from a single test item, from a single PT round. Following the identification of data sets that contain a minimum of ten results from an accredited laboratory, and ten results from a non-accredited laboratory, the remaining data comprised 252 analyte/matrix combinations, 14 844 individual data sets and 1 124 630 participant results. Assigned values and standard deviations of proficiency assessment were calculated using Algorithm A from ISO 13528, and z-scores calculated for all reported results, regardless of accreditation status. Comparisons were made of z-scores between accredited and non-accredited laboratories for the data as a whole, as well as for subsets of the data partitioned into groups such as inorganic tests, organic tests and microbiological tests. In all cases examined, the percentage of both Questionable and Unsatisfactory performance was higher for non-accredited laboratories than for accredited laboratories. A comparison was also made between accredited and non-accredited laboratories of the percentage of consecutive Unsatisfactory performance for the same analyte over a ten year period. Finally, comparisons were made for the first, second and third time participation to assess the impact of PT scheme familiarity. This examination shows that accredited laboratories continually outperform non-accredited laboratories as a group.
PubDate: 2017-04-21
DOI: 10.1007/s00769-017-1262-z

• Mass emissions and carbon trading: a critical review of available
reference methods for industrial stack flow measurement
• Authors: C. Dimopoulos; R. A. Robinson; M. D. Coleman
Abstract: Abstract Flow measurements in industrial ducts and stacks are combined with pollutant or greenhouse gas concentrations to deduce mass emissions. These are then used to populate pollutant emission inventories and are traded under emissions trading schemes. Reference methods for flow are described in ISO 10780 and more recently in EN ISO 16911-1. This paper discusses the key differences between the two standards. We consider sources of error in flow measurement and discuss how each standard addresses them. We find that EN ISO 16911-1 introduces a series of improvements that when combined provide critical uncertainty gains that support compliance with the EU’s Emissions Trading System (EU ETS). All these areas are either not addressed or only partially dealt with in ISO 10780. More specifically, EN ISO 16911-1, (a) specifies a wider range of reference techniques enabling the optimal one to be used for different flue gas environments. (b) Provides a method to correct for cyclonic flow effects. (c) Addresses measurement assembly misalignment and specifies tolerance values for it and (d) provides wall effect correction factors. Most importantly, it has been validated through laboratory and field work. However, the quality control specified in EN ISO 16911-1 is more suitable for measurements to support EU ETS requirements and at times can be too onerous for pollutant mass emission reporting that will usually have less stringent uncertainty requirements.
PubDate: 2017-03-24
DOI: 10.1007/s00769-017-1261-0

• Organisation of proficiency schemes by testing and calibration
laboratories
• Authors: Rodrigo Leão Mianes; Carla Schwengber ten Caten
Abstract: Abstract Each year, an increasing demand for proficiency testing is seen in the world. Participating in this type of activity has been adopted by testing and calibration laboratories, accredited under the ISO/IEC 17025 standard (General requirements for the competence of testing and calibration laboratories), as a means to meet normative and regulatory requirements. Nevertheless, the availability of proficiency testing schemes organised by providers accredited under the ISO/IEC 17043 standard (Conformity assessment—General requirements for proficiency testing) has been insufficient, which poses challenges to laboratories. Considering the similarities between requirements present in both standards, which would allow for their coexistence in a management system, this paper presents an analysis of potential conflicts of interest within an organisation operating simultaneously as proficiency testing provider and testing and calibration laboratory. Aspects of confidentiality, impartiality and undue internal pressures are discussed, and a procedure is proposed to mitigate such conflicts through a web application that codifies the relationship between laboratories and results with no human interaction. In order to minimise possible subjective aspects, the study was validated by a group of metrology specialists. It was concluded that the proposed simultaneous operation is possible and can effectively contribute to reduce shortage in the availability of such a service.
PubDate: 2017-03-17
DOI: 10.1007/s00769-017-1260-1

• PAH analysis in biomass combustion wastes: an approach to evaluate bias
and precision of analytical results using routine samples
• Authors: Susana García-Alonso; Rosa María Pérez-Pastor; David Sanz-Rivera; Enrique Rojas-García; Jesús Rodríguez-Maroto
Abstract: Abstract The aim of this work was to optimize and evaluate an analytical procedure to determine selected polycyclic aromatic hydrocarbons (PAHs) using real samples. Samples of ash were collected during biomass combustion tests under different operating conditions during one week. PAHs were quantified using liquid chromatography with fluorescence detection. Samples were extracted by a simple sonication/agitation method using small amounts of solvent and samples. This paper includes how the performance (bias and precision) of the proposed method was estimated from the analyses of samples. In order to obtain reliable data, we estimated the possible presence of two types of analytical bias: bias proportional bias to the level of analyte, expressed as recovery, and constant bias, comparing results from analyses of different ash masses. Apart from bias studies, the analytical variability was also evaluated as intermediate precision from the overall analyses of different routine samples, with different mass fraction levels and test dates. Intermediate precision values were reduced among 5 % to 10 % when measures on the optimized sample sizes and similar mass fraction levels were taken. The use of samples is rarely applied to assess trueness of analytical methods. Therefore, the presented findings can be considered as an interesting contribution to the analytical chemistry research field.
PubDate: 2017-03-14
DOI: 10.1007/s00769-017-1257-9

• Use of ETAAS, FAAS and ICP-OES for production and post-certification
monitoring of a multielemental certified reference material according to
national regulation limits for elements in drinking water
• Authors: Christian Uribe; Elmer Carrasco; Steve Acco
Abstract: Abstract This paper describes the development of a certified reference material (CRM), produced in the National Institute of Quality from Peru (INACAL) in order to provide a tool for assurance and quality control of nine elements in drinking water. Atomic absorption spectrometry (ETAAS or FAAS) allowed for measurements during the 18-month certification process. ETAAS or ICP optical emission spectrometry was used for 24-month post-certification monitoring measurements. CRM production took into account requirements of ISO Guides 34 and 35 for production of reference materials and criteria of the JCGM GUM and Eurachem QUAM Guides for uncertainty calculation. Mass fractions chosen for batch gravimetric preparation were based on the maximum permissible limits of the National Regulation for Drinking Water Quality in Peru. Characterization analytical measurements were performed using the bracketing calibration technique, applying a randomized 10-replicate measurement sequence and adjusting (matrix matching) the nitric acid concentration for all measured solutions. Characterization resulted from the combination of gravimetric preparation and analytical atomic absorption measurement results. Main sources of uncertainty were identified from the homogeneity study, characterization and the stability study. Expanded relative uncertainties for the assigned mass fractions (ng/g) of Pb, Cd, Ni, As, Cr, Cu, Zn, Mn and Al in the CRM produced were between 0.8 % and 1.9 %. INACAL’s capability to achieve the stated uncertainties has been confirmed through successfully participating in a comparison of the Inter-American Metrology System (SIM-QM-S2). All declared results (ETAAS and FAAS) were comparable to those declared by primary methods of other participants in this comparison.
PubDate: 2017-03-09
DOI: 10.1007/s00769-017-1258-8

• ETV-ICP-OES: a useful technique for homogeneity study of trace element in
metals—application to the homogeneity study of 23 elements in
electrolytic copper
• Authors: Thomas Bacquart; Juergen Hassler; Thomas Vogt; Peter Perzl; Sascha Steigerwald; Wieland Schmidt; Marc Sterckx; Thomas P. J. Linsinger
Abstract: Abstract Solid sampling techniques can perform multi-elemental determination on large number of samples in repeatable conditions without sample preparation, making them valuable tools for the homogeneity testing of reference materials. Even if techniques like glow discharge mass spectrometry are often used for large samples, the application to small chips was not well documented due to the small sample mass. This study compares two analytical methods for homogeneity studies of Ag, Al, As, Au, Bi, Cd, Co, Cr, Fe, In, Mg, Mn, Ni, P, Pb, Sb, Se, Si, Sn, Te, Ti, Zn and Zr in two electrolytic copper materials in the format of chips (ERM-EB074C and ERM-EB075C): (a) digestion methods: acid dissolution followed by ICP-MS or ICP-OES and (b) solid sampling method using electrothermal vaporization coupled with inductively coupled plasma optical emission spectrometry (ETV-ICP-OES). The same 10 units were analysed in 3–5 replicates by the different methods. ETV-ICP-OES was more precise than digestion methods with relative standard deviations of less than 8 % for most elements. The between-unit uncertainties determined by ETV-ICP-OES were lower than the values reported by the digestion methods. ETV-ICP-OES is a very interesting alternative to the digestion methods for large homogeneity study involving large number of trace elements. Also, the intrinsic sample inhomogeneity (minimum sample intake) was re-evaluated using the results of ETV-ICP-OES (sample intake: 3 mg) for the two materials. The minimum sample intake of several elements (e.g. Au Pb, Se and Te) was evaluated to be lower than the 10 mg reported for the two materials.
PubDate: 2017-03-06
DOI: 10.1007/s00769-017-1254-z

• Criteria for using proficiency test results for estimation of measurement
uncertainty: feed analysis example
• Authors: Waldemar Korol; Jolanta Rubaj; Grażyna Bielecka; Sławomir Walczyński; Joanna Reszko-Zygmunt; Ryszard Dobrowolski
Abstract: Abstract On the basis of long-standing proficiency testings (PTs) for the small number of PT participants p (7 ≤ p ≤ 30), laboratory bias and uncertainty were calculated by applying inter-laboratory experimental approaches. Uncertainty was estimated in two ways, according to Eurolab TR No 1/2007 and Nordtest TR 537 (2012). In the case of 24 tested feed components (basic nutrients, macro- and microelements, undesirable elements and some feed additives including vitamins A and E, lysine, threonine, methionine and urea) in the large variety of feed samples, differences between the expanded uncertainties calculated according to Eurolab TR No 1/2007 and Nordtest TR 537 did not exceed 1.4 % for all tested feed and analytes in wide concentration ranges. In order to get a reliable evaluation of bias and uncertainty, minimum of 6 PT rounds and a sufficient number of laboratories participating (p ≥ 10) are recommended. When the above parameters are applied and the standard deviation of the bias s bias ≤ 5 %, the expression s bias 2 /n can be omitted while calculating bias. Generally, both approaches fit the purpose of feed evaluation and the calculated uncertainties can be used for compliance assessment.
PubDate: 2017-03-03
DOI: 10.1007/s00769-017-1252-1

• LC–MS/MS quantification of ractopamine in bovine and swine muscle:
stability of matrix-matched calibration solutions
• Authors: Leila Rodrigues Caldeira; Josefa Abucáter Lima; Flávio Alves Santos; Mary Ane Gonçalves Lana; Ana Cláudia dos Santos Rossi Ribeiro; Elcio Cruz de Oliveira
Abstract: Abstract Ractopamine is used as an animal feed additive, but its adverse effects led to the necessity of the current monitoring programs of ractopamine residues in food products, so its reliable quantification is indispensable. This work aims to demonstrate the stability of solutions of ractopamine used for calibration of a liquid chromatography–tandem mass spectrometry method. Naturally contaminated samples with ractopamine were quantified using solutions prepared on different days. The stability study was based on an empirical model that considered a straight line (slope = 1) to describe the degradation mechanism. No significant change in the slope was detected. It could be concluded that solutions underpinning calibration curves at two different working intervals were stable for at least 11 months and 5 months, respectively.
PubDate: 2017-03-01
DOI: 10.1007/s00769-017-1255-y

• Risk-based thinking for chemical testing
• Authors: Siu-kay Wong
Abstract: Abstract As a result of the changes to the ISO 9001 in 2015, integration of risk-based thinking into the quality management system is going to be a new requirement in ISO/IEC 17025. Though the concept of risk should not be new to the testing laboratories as it has been implicit in the previous editions of ISO 9001 and ISO/IEC 17025 as well, there might be concern on how risk-based thinking could be introduced to their daily operations in a practical and effective way. As a means to address the concern, this paper recommends an initial process review followed by an ongoing risk management process. Besides, a number of potential risks were identified and ways to avoid them were also discussed. Furthermore, there were discussions on the implementation of the risk management process and how could the management make use of the outcome of regular assessments to explore opportunities for increasing the effectiveness of the management system, achieving improved results and preventing negative effects.
PubDate: 2017-02-28
DOI: 10.1007/s00769-017-1256-x

• New Japanese certified reference materials for electrolytic conductivity
measurements
• Authors: Toshiaki Asakai; Igor Maksimov; Sachiko Onuma; Toshihiro Suzuki; Tsutomu Miura; Akiharu Hioki
Abstract: Abstract The National Metrology Institute of Japan (NMIJ) has established three certified reference materials (CRMs) in electrolytic conductivity with a primary Jones-type cell: aqueous solutions of potassium chloride with different molalities (1 mol kg−1, 0.1 mol kg−1 and 0.01 mol kg−1) all supplied in glass bottles. The uncertainties were estimated from standard uncertainties of measurements (impedance, temperature and integrity of cell geometry), measurement’s repeatability, homogeneity of a batch and the storage stability of solutions. The storage stability of candidate NMIJ CRMs of upper and lower concentrations was examined with a secondary cell.
PubDate: 2017-02-27
DOI: 10.1007/s00769-017-1253-0

• Overview of proficiency testing provision in pharmaceutical area in Brazil

• Authors: Carlos Eduardo de Oliveira Pereira; Mateus Araújo Castro e Souza; Gerson Antônio Pianetti; Scheilla Vitorino Carvalho de Souza
Abstract: Abstract An historical review indicated that the provision of proficiency testing (PT) in the pharmaceutical area in Brazil is critical. Three providers were identified in the period between 2002 and 2015; only one provider was regular, but none was accredited according to the requirements of ISO 17043. A PT was organized without registration fees for educational purposes for the determination of mefenamic acid (2-[(2,3-dimethylphenyl)amino]benzoic acid) in raw materials. Proficiency test items consisted of a mixture of mefenamic acid and polyvinylpyrrolidone in the mass ratio 90:10. This proportion was used to simulate an adulterated raw material. Homogeneity and stability testing was performed and indicated that the materials were suitable for use in the PT scheme. First, 68 pharmaceutical laboratories, of which five were ISO 17025 accredited, were contacted to disseminate information about the specific PT and the benefits of this important quality assurance tool. Then, the proficiency test items were sent to the 13 registered participants, of which two were ISO 17025 accredited. In addition, the participating laboratories were surveyed regarding the technical and management aspects of their quality management system (QMS), such as the status of the accreditation process according to the ISO 17025 requirements, staff training, equipment calibration and participation in other PT schemes. All 11 participants that reported results in the study adopted the United States Pharmacopoeia Official Method. Only one laboratory, representing 9.1 % of the participants, had an unsatisfactory z-score result. Factors such as the reduced number of ISO 17025 accredited laboratories, the low number of participants in the educational PT, the high proportion of laboratories that participated for the first time and the portion of the participants who did not know about PT and its importance were considered as determinants for the restricted availability of the PT supply for medicines, as evidenced in the present study in Brazil. Thus, an urgent need for nationwide actions was identified to promote the critical consciousness of managers regarding QMS in pharmaceutical laboratories, including the importance of participation in PT schemes, as well as the importance of encouraging the providers already structured to broaden their scope in this area.
PubDate: 2017-02-16
DOI: 10.1007/s00769-017-1251-2

• Congress, conferences, workshops and courses
• PubDate: 2017-02-04
DOI: 10.1007/s00769-017-1250-3

• Discussion on classification and performance evaluation of diversified
testing procedures
• Authors: Lu Xiaohua; Li Hongmei
Abstract: Abstract More and more testing procedures with different principles are being developed covering both quantitative and qualitative analyses. To ensure the reliability of them and relevant testing results, performance evaluation and method validation are necessary. Following the investigation into a variety of testing procedures, this paper is intended to discuss the rational classification of them according to the nature and purpose of testing. Five kinds of testing procedures are summarized according to different combination of input and output properties of the testing model, which are properties on nominal, ordinal, interval and ratio scales. On this basis, the method validation and performance evaluation parameters, statistical approaches and tools available for each group of testing procedures are discussed. The classification of testing procedures seems helpful for inter-comparison of testing procedures with different purposes and application fields, and the development of some general rules for the performance evaluation and validation of them.
PubDate: 2017-02-04
DOI: 10.1007/s00769-017-1249-9

• Current American landscape in laboratory accreditation according to
ISO/IEC 17025
• Authors: Inês Hexsel Grochau; Carla Schwengber ten Caten; Maria Madalena de Camargo Forte
Abstract: Abstract The number of laboratories worldwide seeking accreditation has increased considerably in the last years. These laboratories are from different institutions, some of them higher education institutions (HEIs) and research institutes. The aim of this work is to present the current landscape of accreditation of testing and calibration laboratories, according to ISO/IEC 17025 standard, in the American Continent (North, Central and South America). Data on accredited laboratories were taken from the Web sites of accreditation bodies signatories to the International Laboratory Accreditation Cooperation Mutual Recognition Arrangement. The accredited laboratories were classified by institution type. Countries with a high number of accredited HEI laboratories were identified, as well as a correlation between gross domestic product and total number of accredited laboratories. North American countries have the highest total numbers of accredited laboratories, except for Brazil in South America. This survey highlights strategies and activities adopted in some countries that resulted in high number of accredited HEI laboratories.
PubDate: 2017-01-24
DOI: 10.1007/s00769-017-1248-x

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