Subjects -> CHEMISTRY (Total: 1001 journals)
    - ANALYTICAL CHEMISTRY (59 journals)
    - CHEMISTRY (726 journals)
    - CRYSTALLOGRAPHY (23 journals)
    - ELECTROCHEMISTRY (28 journals)
    - INORGANIC CHEMISTRY (45 journals)
    - ORGANIC CHEMISTRY (49 journals)
    - PHYSICAL CHEMISTRY (71 journals)

CHEMISTRY (726 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
Accounts of Materials Research     Hybrid Journal  
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 36)
ACS Applied Polymer Materials     Hybrid Journal   (Followers: 15)
ACS Catalysis     Hybrid Journal   (Followers: 78)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 25)
ACS Combinatorial Science     Hybrid Journal   (Followers: 25)
ACS Macro Letters     Hybrid Journal   (Followers: 34)
ACS Materials Letters     Open Access   (Followers: 4)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 49)
ACS Nano     Hybrid Journal   (Followers: 452)
ACS Photonics     Hybrid Journal   (Followers: 19)
ACS Symposium Series     Full-text available via subscription   (Followers: 3)
ACS Synthetic Biology     Hybrid Journal   (Followers: 40)
Acta Chemica Iasi     Open Access   (Followers: 8)
Acta Chemica Malaysia     Open Access  
Acta Chimica Slovaca     Open Access   (Followers: 4)
Acta Chimica Slovenica     Open Access   (Followers: 2)
Acta Chromatographica     Full-text available via subscription   (Followers: 9)
Acta Facultatis Medicae Naissensis     Open Access   (Followers: 1)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 10)
Acta Scientifica Naturalis     Open Access   (Followers: 3)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 9)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 10)
Adsorption Science & Technology     Open Access   (Followers: 9)
Advanced Electronic Materials     Hybrid Journal   (Followers: 7)
Advanced Functional Materials     Hybrid Journal   (Followers: 81)
Advanced Journal of Chemistry, Section A     Open Access   (Followers: 15)
Advanced Journal of Chemistry, Section B     Open Access   (Followers: 14)
Advanced Science Focus     Free   (Followers: 7)
Advanced Theory and Simulations     Hybrid Journal   (Followers: 5)
Advanced Therapeutics     Hybrid Journal   (Followers: 1)
Advances in Chemical Engineering and Science     Open Access   (Followers: 108)
Advances in Chemical Science     Open Access   (Followers: 50)
Advances in Chemistry     Open Access   (Followers: 39)
Advances in Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 21)
Advances in Drug Research     Full-text available via subscription   (Followers: 27)
Advances in Environmental Chemistry     Open Access   (Followers: 11)
Advances in Enzyme Research     Open Access   (Followers: 13)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 20)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 11)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 35)
Advances in Nanoparticles     Open Access   (Followers: 20)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 20)
Advances in Polymer Science     Hybrid Journal   (Followers: 54)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 19)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 22)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 7)
Advances in Science and Technology     Full-text available via subscription   (Followers: 17)
Aerosol Science and Engineering     Hybrid Journal  
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 6)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Aggregate     Open Access   (Followers: 3)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 3)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alchemy : Journal of Chemistry     Open Access   (Followers: 5)
Alchemy : Jurnal Penelitian Kimia     Open Access   (Followers: 2)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
Alotrop     Open Access  
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 71)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 24)
American Journal of Chemistry     Open Access   (Followers: 41)
American Journal of Plant Physiology     Open Access   (Followers: 13)
Analyst     Full-text available via subscription   (Followers: 40)
Analytical Science Advances     Open Access   (Followers: 2)
Angewandte Chemie     Hybrid Journal   (Followers: 234)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 352)
Annales Universitatis Mariae Curie-Sklodowska, sectio AA – Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 8)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 4)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 6)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 9)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 13)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 16)
Antiviral Chemistry and Chemotherapy     Open Access   (Followers: 2)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 12)
Applied Spectroscopy     Full-text available via subscription   (Followers: 27)
Applied Surface Science     Hybrid Journal   (Followers: 33)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Applied Chemistry Research     Open Access   (Followers: 2)
Asian Journal of Biochemistry     Open Access   (Followers: 3)
Asian Journal of Chemical Sciences     Open Access   (Followers: 1)
Asian Journal of Chemistry and Pharmaceutical Sciences     Open Access   (Followers: 2)
Asian Journal of Physical and Chemical Sciences     Open Access   (Followers: 3)
Atomization and Sprays     Full-text available via subscription   (Followers: 8)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 7)
Avances en Quimica     Open Access  
Biochemical Pharmacology     Hybrid Journal   (Followers: 11)
Biochemistry     Hybrid Journal   (Followers: 483)
Biochemistry Insights     Open Access   (Followers: 7)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 11)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 3)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 4)
Biomacromolecules     Hybrid Journal   (Followers: 27)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 11)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 4)
BioNanoScience     Partially Free   (Followers: 6)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 214)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 88)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 18)
Biosensors     Open Access   (Followers: 4)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of Institute of Chemistry and Chemical Technology, Mongolian Academy of Sciences     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 1)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 26)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 5)
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 13)
Canadian Mineralogist     Full-text available via subscription   (Followers: 7)
Carbohydrate Polymer Technologies and Applications     Open Access   (Followers: 3)
Carbohydrate Polymers     Hybrid Journal   (Followers: 13)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 76)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 9)
Catalysis Science and Technology     Hybrid Journal   (Followers: 13)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysts     Open Access   (Followers: 14)
Cell Reports Physical Science     Open Access  
Cellulose     Hybrid Journal   (Followers: 17)
Cereal Chemistry     Full-text available via subscription   (Followers: 6)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 3)
ChemCatChem     Hybrid Journal   (Followers: 11)
Chemical and Engineering News     Free   (Followers: 24)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 88)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 28)
Chemical Physics Letters : X     Open Access   (Followers: 4)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 4)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 25)
Chemical Reviews     Hybrid Journal   (Followers: 266)
Chemical Science     Open Access   (Followers: 44)
Chemical Science International Journal     Open Access   (Followers: 1)
Chemical Technology     Open Access   (Followers: 71)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 56)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 23)
ChemInform     Hybrid Journal   (Followers: 9)
Chemistry     Open Access  
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 31)
Chemistry & Industry     Full-text available via subscription   (Followers: 8)
Chemistry - A European Journal     Hybrid Journal   (Followers: 223)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 20)
Chemistry Africa : A Journal of the Tunisian Chemical Society     Hybrid Journal  
Chemistry and Materials Research     Open Access   (Followers: 24)
Chemistry Central Journal     Open Access   (Followers: 5)
Chemistry Education Research and Practice     Free   (Followers: 8)
Chemistry Education Review     Open Access   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry Letters     Full-text available via subscription   (Followers: 49)
Chemistry of Heterocyclic Compounds     Hybrid Journal   (Followers: 4)
Chemistry of Materials     Hybrid Journal   (Followers: 337)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 10)
Chemistry World     Full-text available via subscription   (Followers: 20)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 1)
ChemistrySelect     Hybrid Journal  
Chemistry–Methods     Open Access   (Followers: 2)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
ChemNanoMat     Hybrid Journal   (Followers: 1)
Chemoecology     Hybrid Journal   (Followers: 3)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 14)
Chemosensors     Open Access   (Followers: 1)
ChemPhotoChem     Hybrid Journal  
ChemPhysChem     Hybrid Journal   (Followers: 14)
ChemPlusChem     Hybrid Journal   (Followers: 2)
Chempublish Journal     Open Access   (Followers: 1)
ChemSystemsChem     Hybrid Journal   (Followers: 2)
ChemTexts     Hybrid Journal   (Followers: 1)
CHIMIA International Journal for Chemistry     Open Access   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 13)
Chromatographia     Hybrid Journal   (Followers: 22)
Chromatography     Open Access   (Followers: 3)
Chromatography Research International     Open Access   (Followers: 5)
Ciencia     Open Access   (Followers: 1)
Clay Minerals     Hybrid Journal   (Followers: 9)
Cogent Chemistry     Open Access   (Followers: 3)
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 12)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 8)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 24)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)

        1 2 3 4 | Last

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Journal Cover
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement
Journal Prestige (SJR): 0.316
Citation Impact (citeScore): 1
Number of Followers: 36  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0949-1775 - ISSN (Online) 1432-0517
Published by Springer-Verlag Homepage  [2658 journals]
  • Estimation of the error due to radial displacements in a conductivity cell
           (jones type)

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      Abstract: The paper presents the results of a study of errors arising in the presence of radial displacements in a conductometric differential cell with a removable central part, in the process of measuring the electrolytic conductivity of solutions. The analysis of the component of the measurement error of the cell resistance, caused by the presence of displacement at the cell joint, as a systematic error is carried out. This error is caused by the appearance of additional resistance of the solution column in the cell due to a decrease in the cross-sectional area at the joint with a radial displacement and a corresponding change in the path of electric current flow in the cell. This additional resistance is estimated using computer cell modeling and finite element method. To describe the joint of the displaced cell parts, the parameter KJ is used, which depends on the diameter of the tubes and the magnitude of the displacement. Expressions for the errors and dependences for KJ are obtained, with the help of which it is possible to estimate the component of the error in measuring the resistance for real cells due to radial displacements. The results of the work can be used to estimate the component of the measurement error of electrolytic conductivity due to the presence of radial displacements of a known value for real cells. This will make it possible to ascertain whether or not this source of error should be taken into account when estimation the measurement uncertainty of electrolytic conductivity with the known characteristics of the cell fixing devices.
      PubDate: 2021-10-05
       
  • Challenges for the estimation of uncertainty of measurements made in situ

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      Abstract: In situ measurements are made without the removal of a physical sample and have many advantages over traditional ex situ measurements, made on a removed sample usually in a remote laboratory. The quality of ex situ measurements is usually expressed primarily in terms of their measurement uncertainty, including that arising during the sampling process. However, estimates of uncertainty for in situ measurement values have not usually included this uncertainty from sampling (UfS). It is argued that the making of an in situ measurement inevitably includes the taking of an ‘undisturbed sample’ that generates UfS, which should be included in the estimate of measurement uncertainty. Because undisturbed samples are not prepared or mixed, as is usual for removed samples, the heterogeneity of the analyte concentration in the sampling target is the primary source of UfS. Existing methods for estimating UfS for ex situ measurements can broadly be applied to in situ measurements. However, four extra challenges that limit the design and uptake of uncertainty estimation for in situ methods are identified, and possible solutions and actions required are discussed. Examples of in situ measurements considered include Pb in top soil by hand-held PXRF, 137Cs at a nuclear site by portable gamma-ray spectrometry, and bilirubin in new-born infants by hand-held reflectance photometry.
      PubDate: 2021-10-01
       
  • Proficiency testing to evaluate the effectiveness of laboratories
           analyzing active ingredient in formulation samples

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      Abstract: This paper describes the organization and evaluation of the proficiency tests (PTs) organized by the Italian National Institute of Health (ISS) during 2018 and 2019. The aim of the PTs was to determine the quantity of active ingredient in various formulations of plant protection products (PPPs). In 2018, the Italian National Institute of Health (ISS) had organized PTs for the determination of Cymoxanyl, Oxamyl, and Methomyl in three different plant protection product (PPP) formulations. This is the first PT in Italy that uses a commercially available plant protection product in a different formulation, such as a wettable powder (WP), granule (GR), and soluble liquid (SL). In 2019, the ISS organized proficiency testing for the determination of Amisulbron, Dimethomorph, Pirimiphos-methyl, and Propiconazole in four different formulations of PPPs. For this proficiency testing, the commercial PPPs was obtained from the market in the formulation, as wettable dispersible granules (WDG), wettable powder (WP), liquid (L), or emulsifiable concentrate (EC). In 2018, all laboratories obtained data with acceptable values of z-score within limits, except for three of them that returned z-score values higher than 3.5 for the active substances Cymoxanil and Methomyl. In 2019, all laboratories obtained data with acceptable values of z-score within limits, except for three laboratories that returned z-score values higher than 3.5 for the active substances. The performance of the laboratories expressed in terms of modified z-score was satisfactory by almost all participants for all substances.
      PubDate: 2021-09-28
       
  • Impurity analyses for a certified reference material of high-purity sulfur
           dioxide gas (NMIJ CRM 3402)

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      Abstract: A certified reference material (CRM) of sulfur dioxide (SO2) gas, with a certified value of purity, was developed for the preparation of primary reference gas mixtures of SO2 in nitrogen (N2) gas. Impurity analyses by “subtraction method” were performed using a gas chromatograph (GC) with a thermal conductivity detector (TCD), a GC with a flame ionization detector (FID), and a Fourier transform infrared spectrometer (FT-IR), all calibrated with gas mixtures traceable to the Internal System of Units (SI). First, qualitative analysis using the FT-IR was performed on two samples of liquefied SO2 of different quality grades, contained in gas cylinders. Using the FT-IR and the GC-TCD, carbon dioxide (CO2) was detected in the lower- and higher-grade cylinders at approximately 0.5 cmol/mol and 5 µmol/mol, respectively. The FT-IR did not detect any sulfur compound peaks, other than SO2, in the higher-grade sample. Other atmospheric constituents such as N2, oxygen (O2), water (H2O), argon (Ar), and methane (CH4) were also tested for in this sample. The detection limit of H2O in the FT-IR was 49 µmol/mol, while those of N2, O2, Ar, by the GC-TCD were a few µmol/mol, and CH4, using the GC-FID, were better than 1 µmol/mol. The high detection limit of H2O was due to large baseline fluctuations when measuring the FT-IR spectrum of the SO2 gas. Responses corresponding to these analytes were not detected or were detected below the detection limits. For an estimation of purity by the subtraction method, each reported mol fraction was regarded as half the value of each detection limit, except for the CO2. The purity and its expanded uncertainty [k = 2] of the high-purity SO2 gas by the subtraction method were 99.9964% and 0.0028%, respectively.
      PubDate: 2021-09-28
       
  • Human health risk assessment of pesticide residues in pointed gourd
           collected from retail markets of Dhaka City, Bangladesh

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      Abstract: The increased level of pesticide residues in vegetables is a potential threat to human health, especially in children. In this study, human health risk assessment associated with the presence of pesticide residues in fresh pointed gourd (Trichosanthes dioica Roxb.) samples purchased from different markets of Dhaka City, Bangladesh, was done. Six selected organophosphorus pesticide residues (dimethoate, fenitrothion, chlorpyrifos, quinalphos, diazinon and malathion) in the samples were determined using modified QuEChERS extraction and gas chromatography coupled with flame thermionic detector. The method was validated by assessing the accuracy, precision, linearity, limit of detection (LOD) and limit of quantification (LOQ). The average recoveries of the selected pesticides ranged from 85 to 106% with precision in case of repeatability  ≤ 10% and combined uncertainty < 7 % in five fortification levels of 0.01 mg kg−1, 0.05 mg kg−1, 0.1 mg kg−1, 0.2 mg kg−1 and 0.3 mg kg−1. The linearity of the calibration curve was very good and the relative residuals were <  20 %. The LOD ranged from 0.002 mg kg−1 to 0.003 mg kg−1 and the LOQ was determined at 0.01 mg kg−1 for all the selected analytes. This method was applied successfully for the residue analysis of fresh pointed gourd samples. Among the analyzed samples, 8 (11.43 %) had pesticide residues, of which none had multiple pesticide residues. All of the contaminated samples contained residue above European Union-Maximum Residue Levels. Out of the eight contaminated samples, health risk was exceeded the acceptable value (< 1) in five for adults and seven for children associated with the residues of chlorpyrifos, quinalphos, diazinon and dimethoate. This finding reveals the public health concern due to potential of pesticide toxicity in vegetables for the consumers. Therefore, continuous monitoring on the use of pesticides in vegetables should be strengthened.
      PubDate: 2021-09-12
      DOI: 10.1007/s00769-021-01475-7
       
  • Boxplot fences in proficiency testing

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      Abstract: The box and whiskers plot (boxplot) has shown to be an effective data visualization tool in proficiency testing. The boxplot provides a quick visual summary of the considered data set . All the descriptive aspects of data reported in a round of a proficiency test can be studied with this plot. Location (through median and quartiles), spread (by means of the interquartile range), shape (position of the median in the box), and possible outliers (values beyond of the fences) are simultaneously observed with the boxplot. In this paper, we propose a modification of the inner fences of the boxplot, in such a way that they are in accordance with the approach based on the z score (standard ISO 13528) and therefore useful to recognize graphically questionable and unacceptable values in proficiency testing.
      PubDate: 2021-08-24
      DOI: 10.1007/s00769-021-01474-8
       
  • A review of proficiency exercises offered by the Veterinary Laboratory
           Investigation and Response Network (Vet-LIRN) and Moffett Proficiency
           Testing Laboratory from 2012 to 2018

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      Abstract: The Food and Drug Administration’s Veterinary Laboratory Investigation and Response Network is comprised of more than 40 animal diagnostic laboratories within North America and offers voluntary Proficiency Exercises to these participating laboratories. The joint Proficiency Exercise Program is run in collaboration with the Center for Food safety and Nutrition and Institute for Food safety and Health, located at the Moffett Proficiency Testing Laboratory. From 2012 to 2018, the Proficiency Exercise Program offered 20 proficiency tests or interlaboratory comparison exercises focused on veterinary analytes of interest. The program evaluated performance of laboratories, individual analysts, and the methods used. Over the six-year period, the program improved exercise schemes, as well as offered network laboratories exercises with analytes not routinely seen such as animal tissue with naturally occurring residues. Animal diagnostic laboratories can use performance results to assist with accreditation, demonstrate proficiency, and improve diagnostic capabilities.
      PubDate: 2021-06-15
      DOI: 10.1007/s00769-021-01471-x
       
  • Improved performance of neutron activation analysis laboratories by
           feedback workshops following interlaboratory comparison rounds

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      Abstract: The International Atomic Energy Agency (IAEA) implemented an innovative project for assisting neutron activation analysis laboratories in improving the validity of their results by feedback workshops for discussion of results from participation in interlaboratory comparisons rounds in 2010. The participants learned during these meetings to identify the most probable sources of errors in their analytical procedures and how to implement corrective actions to prevent reoccurrence. The outcome of successive rounds between 2010 and 2018 is discussed and experiences during the feedback workshops are given. The quantitative evaluation of the results shows an overall improvement in satisfactory performance. Moreover, there is a clear indication that improvements are consolidated in most laboratories but also stimulate laboratories to develop to a higher level of excellence. Regional differences in performance are also analysed.
      PubDate: 2021-06-14
      DOI: 10.1007/s00769-021-01473-9
       
  • Reference measurement procedure for the determination of mass fraction of
           fat content in food

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      Abstract: This article develops the reference measurement procedure (RMP), including acid hydrolysis, Randall extraction, evaporation of solvent, and weighing of dry residue in the determination of mass fraction of fat content. This paper’s RMP applies to dairy, meat, and egg products, and to baby food. In order to develop this RMP, selection and optimization of hydrolysis and extraction parameters were carried out. The paper takes into consideration the components of measurement uncertainty arising from the contributions of equipment and reagents. It also evaluates measurement equations and methodological factors. This article also presents the results of an inter-laboratory comparison of the determination of mass fraction of fat in Russian enterprises’ dairy products. These results demonstrate that the RMP developed by this research had the highest level of accuracy and the absence of bias in the measurement results as compared to other routine methods. Experiments carried out during the participation of UNIIM in an inter-laboratory comparison organized by MUVA Kempten GmbH (Germany) confirmed the equivalence of the RMP developed by this research with similar foreign measurement methods. The results of the work will ensure coherence of the results of determining the fat content in food products and food raw materials in the Russian Federation, and their conformity with the results obtained in other countries.
      PubDate: 2021-06-14
      DOI: 10.1007/s00769-021-01472-w
       
  • Getting started with uncertainty evaluation using the Monte Carlo method
           in R

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      Abstract: The evaluation of measurement uncertainty is often perceived by laboratory staff as complex and quite distant from daily practice. Nevertheless, standards such as ISO/IEC 17025, ISO 15189 and ISO 17034 that specify requirements for laboratories to enable them to demonstrate they operate competently, and are able to generate valid results, require that measurement uncertainty is evaluated and reported. In response to this need, a European project entitled “Advancing measurement uncertainty—comprehensive examples for key international standards” started in July 2018 that aims at developing examples that contribute to a better understanding of what is required and aid in implementing such evaluations in calibration, testing and research. The principle applied in the project is “learning by example”. Past experience with guidance documents such as EA 4/02 and the Eurachem/CITAC guide on measurement uncertainty has shown that for practitioners it is often easier to rework and adapt an existing example than to try to develop something from scratch. This introductory paper describes how the Monte Carlo method of GUM (Guide to the expression of Uncertainty in Measurement) Supplement 1 can be implemented in R, an environment for mathematical and statistical computing. An implementation of the law of propagation of uncertainty is also presented in the same environment, taking advantage of the possibility of evaluating the partial derivatives numerically, so that these do not need to be derived by analytic differentiation. The implementations are shown for the computation of the molar mass of phenol from standard atomic masses and the well-known mass calibration example from EA 4/02.
      PubDate: 2021-06-06
      DOI: 10.1007/s00769-021-01469-5
       
  • Total cow’s milk protein in cookies: the first interlaboratory
           comparison with a well-defined measurand fit for food allergen risk
           assessment

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      Abstract: A feasibility interlaboratory comparison (ILC) was organised by the European Commission’s (EC) Joint Research Centre (JRC) on the determination of the mass fraction of total cow’s milk protein in baked cookies. The ILC was organised to support Commission Regulation (EU) 1169/2011 on the provision of food information to consumers, including the mandatory allergen food labelling and the harmonisation of measurement procedures used for food allergen analysis. An incurred baked cookie was prepared at the JRC and samples were sent to participants for analysis. The laboratories were asked to report their results as “mass fraction of total cow’s milk protein in baked cookies”. This common well-defined measurand was used for the first time in such an ILC to assess the equivalence of measurement results. Homogeneity and stability of the test material were demonstrated to be adequate. An indicative assigned value was established using the JRC single-laboratory validated method based on liquid chromatography coupled to mass spectrometry (LC–MS), independently from the results reported by the participants. Twenty-three laboratories from the European Network of Food Allergen Detection Laboratories (ENFADL), representing 20 European Union (EU) Member States, reported results. Their laboratory performance was assessed using the percent difference Di score. The participating laboratories applied either enzyme-linked immunosorbent assays (ELISA) or LC–MS. Even though the majority of the laboratories used commercially available ELISA test kits, a significant scatter of all the reported results was observed. This indicates that further harmonisation is required for measurement procedures aiming to determine potentially allergenic constituents in food.
      PubDate: 2021-05-25
      DOI: 10.1007/s00769-021-01470-y
       
  • Proficiency tests: a tool for improvement and testing analytical
           performance at Gamma-Ray Spectroscopy Laboratory

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      Abstract: Participation in proficiency tests is an essential requirement of ISO/IEC 17025 for testing and calibration laboratories. These tests aim to evaluate performance of laboratories for specific analytical methods, identify problems and assist in initiating corrective actions for improvement, find source of error in measurement result and validate uncertainty. The accredited Gamma-Ray Spectroscopy Laboratory at the Lebanese Atomic Energy Commission, participates yearly in proficiency test organized by the International Atomic Energy Agency (IAEA)-ALMERA Network-Analytical Laboratories for the Measurements of Environmental Radioactivity and the Department of Energy-USA, Mixed Analyte Performance Evaluation Program (MAPEP-DOE-USA). This paper showed how proficiency tests had helped the laboratory to improve adopted analytical protocol through the corrective actions implemented for unacceptable results, and to provide advanced experience to the laboratory staff through the lessons learned. The Results were evaluated based on accuracy and precision criteria. The relative bias, Z-score and precision score values since 2005 are presented and discussed. The laboratory showed high performance over years with acceptable values for different radionuclides in various matrices.
      PubDate: 2021-05-22
      DOI: 10.1007/s00769-021-01468-6
       
  • Statistical internal quality control (SIQC) in chemical measurement—do
           we really understand it'

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      Abstract: Internal quality control (IQC) of routine analysis can be applied in two different ways, statistical IQC and target value IQC. The correct interpretations of the respective control charts differ and are easily confused. This note examines statistical IQC in detail. It shows that its legitimate function is to ensure that variation in the run-to-run performance of the analytical procedure is inconsequential. Statistical IQC per se can say nothing about the uncertainty that can be attributed to the analytical results produced for the test samples. However, given an ‘in-control’ run, analysts can deduce that the uncertainty has not changed since the procedure was validated.
      PubDate: 2021-04-01
      DOI: 10.1007/s00769-021-01467-7
       
  • Progress with the work program of ISO/REMCO during 2020

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      Abstract: The 43rd meeting of the Reference Material Committee of ISO, ISO/REMCO, that was scheduled to take place in Milan, Italy, from 30 June to 3 July 2020 with Accredia, the Italian accreditation body and INRIM, the Italian Metrology Institute as the hosts, was cancelled due to the COVID-19 pandemic. This report shares the details of the important decision that was taken by the ISO Technical Management Board (TMB) in December 2020 to transform ISO/REMCO into an ISO technical committee, ISO/TC 334, Reference materials. The background that led to the decision is provided as well as the implications of the decision for the future of the development of guidance for the production and use of reference materials. The report also gives an update on the progress with the work program of the committee during the past year and the strategy for the future work of the committee.
      PubDate: 2021-04-01
      DOI: 10.1007/s00769-021-01465-9
       
  • Quantitation of hydrogen sulfide reference gas mixtures to provide
           traceability for indoor air quality monitoring

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      Abstract: Accurate measurements for the determination of hydrogen sulfide (H2S) are critical for the compliance with legislation in various industries, including natural gas and environmental sectors such as air pollution monitoring. H2S measurements at ambient level are challenging because H2S tends to adsorb on the internal surfaces of the sample collection devices such as gas cylinders and transfer lines. Prolonged exposure to H2S has known health implications to humans, such as irritation to the nose, throat and airways that results in coughing or inflammation, wheezing and shortness of breath around the chest. H2S is mainly monitored for occupational health and safety and indoor air quality monitoring. It is a highly reactive gas that can easily react with oxygen to form sulfur dioxide (SO2) and with water to form sulfuric acid (H2SO4). The traceability of H2S measurements is achieved through the preparation of reference gas mixtures. These gas mixtures are gravimetrically prepared in accordance with International Organization for Standardization (ISO 6142–1:2015). The H2S reference gas mixtures were produced with the highest metrological capability; thus, the molar mass, purity assessment, and the weighing gave an overall gravimetric relative uncertainty which is less than 0.10% (k = 1). One of the biggest challenges in producing a H2S reference gas mixture is the handling of a gas cylinder from the gravimetric preparation process until the verification stage. This work will detail the improved techniques and measurements used to produce the H2S reference gas mixtures. The internal consistency between the mixtures was verified using a non-dispersive ultraviolet (NDUV) spectroscopy analyzer, an ultraviolet fluorescence spectroscopy (UVFS) analyzer and gas chromatography coupled with a pulsed discharged helium ionization detector (GC-PDHID). Our measurement uncertainty results show that the gravimetric value, internal consistency, adsorption, homogeneity, and stability were within a relative uncertainty of 1.2% as compared to our previous uncertainty of 4.4%. This is a significant improvement for the measurements of H2S reference gas mixtures.
      PubDate: 2021-04-01
      DOI: 10.1007/s00769-021-01461-z
       
  • An empirical study: The multidimensionality of the quality management in
           determining university research laboratories performance

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      Abstract: The empirical study carried out was based on a questionnaire administered to the research laboratories managers of the sciences and techniques faculties across Morocco. This questionnaire is a tool for measuring the level of implementation of good quality management practices in research. It was developed on the basis of standards linked directly or indirectly to quality management in research. Further to the results of this study, an explanatory model was established, based on a multiple linear regression, to identify the existence of an influence of good practices of quality management in research on the performance of Moroccan research laboratories. This model demonstrated that this performance is determined by 4 variables which are: “laboratory management”, “material resources”, good practices linked to “carrying out scientific research activities” and to the “validation and evaluation of the research results”. The major element of influence is undoubtedly the first two variables. This involves that the variation in the overall “laboratory performance” is very sensitive compared to any variation in these two variables. That said, to improve the “laboratory performance”, staff is required to invest in setting up good-quality management practices which are linked to these two variables.
      PubDate: 2021-04-01
      DOI: 10.1007/s00769-021-01466-8
       
  • Application of secondary pH measurement method for homogeneity and
           stability assessment of reference materials

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      Abstract: In this work, the development and optimization of a secondary method for pH measurement using a differential potentiometric cell are described. The method was optimized and validated by measurement of three certified primary buffer solutions (CRMs) with nominal pH values of 4.005, 6.865 and 9.180 at 25 °C. The method was applied to assess homogeneity and stability of phosphate buffer solution with nominal pH of 7.000 at 25 °C which will be used as test item in proficiency testing schemes for pH measurement of testing laboratories. The experiments carried out and described in this article proved that this particular design of secondary differential potentiometric cell requires small volume of solutions, is fast, accurate and precise and is suitable for the characterization of secondary buffer solutions and assessment of homogeneity and stability of buffer solutions.
      PubDate: 2021-04-01
      DOI: 10.1007/s00769-021-01464-w
       
  • Identification key for selection of the matrix type to which a sample
           belongs within the context of GMO analysis

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      Abstract: Analysis of food or feed samples by DNA-based methods first needs a sample preparation before DNA extraction. Due to the large variety of types of food and feed samples, methods must be adapted to the matrices encountered. Within an accreditation scheme, auditors frequently require a clear decision system enabling the technical staff to determine which method has to be used to perform the sample preparation and the DNA extraction. In this paper, we present an identification key that easily determines the type of matrix and the subsequent operations. The method presented is used in the framework of GMO analysis but could be extended to a wide variety of other DNA-based methods applied to food and feed products.
      PubDate: 2021-04-01
      DOI: 10.1007/s00769-021-01462-y
       
  • Preparation of matrix reference material of aflatoxin M 1 in milk powder

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      Abstract: The preparation and characterization of a matrix reference material for aflatoxin M1 in milk powder is described. Milk powder samples containing aflatoxin M1 were found in the screened natural milk samples. The preparation of matrix milk powder samples was developed through steps by vacuum concentration, spray-drying, cooling, mixing, weighing and packaging, and irradiation. This paper has developed a method for the determination of aflatoxin M1 in milk powder by isotope dilution liquid chromatography–tandem mass spectrometry (ID-LC-MS/MS) with immunoaffinity extraction as the pretreatment method, which was validated and determined the content of aflatoxin M1 in milk powder accurately. The homogeneity was studied by analyzing in triplicate for their aflatoxin M1 contents by ID-LC-MS/MS using random sampling schemes. The short-term stability was evaluated at three different storage temperatures (4, 25 and 50 °C) for 0, 3, 5, 7, 14 days, the long-term stability study comprised of measurement after 0, 1, 3, 6, 9, 12 months after storage at 4 °C, and then, analyses were investigated by ID-LC-MS/MS. After the combination determination of 8 laboratories, the final quantity value and expanded uncertainty of matrix reference material of aflatoxin M1in milk powder were: 0.49 ± 0.11 μg/kg, k = 2, P = 0.95, and the matrix reference material is homogenous and stable at 4 °C for at least 12 months, which can provide quality assurance for the later detection accuracy.
      PubDate: 2021-04-01
      DOI: 10.1007/s00769-021-01460-0
       
  • The mycotoxin proficiency testing schemes organized by Turkish National
           Food Reference Laboratory between the years 2013 and 2020

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      Abstract: The Turkish National Food Reference Laboratory has been organizing mycotoxin proficiency tests since 2013. Matrices were mainly selected from the products that Turkey produces and exports most. Therefore, control of mycotoxin contamination in these products intended for domestic consumption and for export to the European Union (EU) and other countries have a special importance. Laboratory controls are one of the important steps in this control. As an external quality control tool, proficiency tests provide the quality assurance of the laboratory test results. For performance evaluation, standard deviation for proficiency assessment is used to calculate z-scores. According to ISO 13528:2015, the standard deviation for proficiency assessment can be determined by experience with previous rounds of proficiency test. As a result of this study, a fit-for-purpose relative standard deviation of 17 % obtained from reevaluation of the previous proficiency tests can be used to calculate standard deviation for proficiency assessment for performance evaluation.
      PubDate: 2021-04-01
      DOI: 10.1007/s00769-021-01463-x
       
 
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