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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: 28

Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0949-1775 - ISSN (Online) 1432-0517
Published by Springer-Verlag

[2352 journals]

Principles for the characterisation and the value assignment of the
candidate reference material in the new ISO Guide 35:2017
- Authors: Thomas P. J. Linsinger; Angelique Botha
  Abstract: The production of reference materials (RMs) is a key activity for the improvement and maintenance of a worldwide coherent measurement system. General requirements for the production of all types of RMs are set out in ISO 17034:2016. These general requirements include a characterisation strategy with a note that references the list of approaches that are discussed in more detail in the new ISO Guide 35:2017. This paper provides an overview of the characterisation approaches explained in technical detail in the new ISO Guide 35:2017, with particular attention being paid to changes from the 2006 edition. Important changes include a clear distinction between the use of a single method in a single-laboratory approach when the method can be validated with a certified reference material (CRM) of the same kind as the candidate reference material compared to when a similar CRM is not available. For the approach where more than one method is used in one or more laboratories, the concept of the importance of the number of independent data sets is explained in more detail. A lot more technical detail is also provided for the use of an interlaboratory comparison for the certification study.
  PubDate: 2019-01-02
  DOI: 10.1007/s00769-018-1364-2
The integration of quality management systems in testing laboratories: a
practitioner’s report
- Authors: Pieter Dehouck; Robert Koeber; Elena Scaravelli; Hendrik Emons
  Abstract: When routine laboratories merge or are taken over by larger entities, their quality management systems usually need to be integrated. In many laboratories, quality management systems according to ISO/IEC 17025 are in place. The integration of the quality management systems is often advantageous in terms of efficiency of operations, reduction in number of processes and consequently amount of quality documentation. However, a number of practical problems, some of them hard to overcome, may be encountered. Examples are: how to deal with multi-site activities showing technical and/or cultural differences, how to merge historically different ways of working and how to overcome psychological resistance to change from laboratory staff. This paper demonstrates a way of working used in our organisation to integrate successfully the quality management systems of several laboratories under one quality management system. The laboratories were located in two different countries (Belgium and Italy) and had activities under ISO/IEC 17025, ISO/IEC 17043 and ISO Guide 34 accreditation. Involvement of the laboratory staff was essential for obtaining a fast and efficient integration.
  PubDate: 2018-12-28
  DOI: 10.1007/s00769-018-1365-1
Proficiency testing for pH measurements: a 3-year evaluation
- Authors: Fransiska Sri Herwahyu Krismastuti; Nurhani Aryana; Ayu Hindayani; Nuryatini Hamim
  Abstract: Chemical Metrology Laboratory, LIPI, organizes an annual proficiency testing (PT) scheme with pH being one of the parameters investigated. This study presents and evaluates the performance of the laboratories that participated in the pH measurement during 3 consecutive years of the PT from 2014 to 2016. The PT test items were prepared by Chemical Metrology Laboratory, LIPI, from high-purity material. The homogeneity testing and stability testing of the PT test items were performed according to ISO 13528:2005. The measured reference value was directly traceable to the pH value of SRM® 185i and 187e produced by NIST, USA, and the expanded uncertainty was calculated according to ISO GUM:2008 with a coverage factor (k = 2), at a 95 % confidence level. Individual laboratory performance was reported in terms of z-scores. In the 2014 scheme, the reference buffer solution was not provided by provider, while in the 2015 and 2016 schemes, reference buffer solutions were distributed to participants alongside the PT test items. The best performance was achieved in 2015, where more than 90 % of the reported results were assessed as satisfactory. The laboratory performance in 2015 coincided with the distribution of two traceable pH standard solutions to participants which allowed them to satisfactorily calibrate their instrumentation. In conclusion, regular PT program is an effective way of demonstrating the effectiveness of quality assurance procedures applied in participating laboratories and provides opportunity for corrective action which will benefit measurements made in the future.
  PubDate: 2018-11-30
  DOI: 10.1007/s00769-018-1362-4
Establishment of proficiency testing programs in the Philippines
- Authors: Leah C. Dajay; Teresita R. Portugal; Jolly C. Climaco; Ma. Rachel V. Parcon; Mildred A. Udarbe; Rose Elaine E. Placio; Prudencio E. Adona
  Abstract: In order to improve the competitiveness of Philippine food products in the global market, the Department of Science and Technology—Food and Nutrition Research Institute initiated proficiency testing (PT) programs on some nutrition labeling components using food matrices commonly exported by the country. The institute realized the need to organize affordable, accessible and reliable PTs designed to address the needs of the local testing laboratories. FNRI organized several PT rounds on different food matrices for the analyses of proximates, minerals, total dietary fiber, saturated fatty acids, cholesterol and vitamin C. More than 20 laboratories (government and private) participated in these PT programs, which helped them obtain/sustain their accreditation to ISO/IEC 17025:2005. In February 2013, the Proficiency Testing Laboratory (PTL) was accredited to ISO/IEC 17043:2010 by the Thailand Bureau of Laboratory Accreditation. This strengthened its credibility by being recognized as the first accredited PT provider in the Philippines. Initially, the scope of the accredited PTs included the analysis of proximates and minerals in infant formula. It was extended to include five different food matrices (infant formula, milk powder, wheat flour, corn-based snack food and powdered concentrate-water-based flavored drinks) for nutrition labeling parameters. The PTL continuously organizes new PT rounds to expand its scope of accreditation.
  PubDate: 2018-11-27
  DOI: 10.1007/s00769-018-1363-3
A comparative investigation of pressure distortion coefficient of a
pneumatic piston gauge and its associated uncertainty using varied
approaches
- Authors: Jasveer Singh; L. A. Kumaraswamidhas; Nita Dilawar Sharma
  Abstract: This paper reports the evaluation of the measurement uncertainty of the pressure distortion coefficient (λ) of a piston gauge using the Monte Carlo method (MCM) and its comparison with results obtained from the GUM (Guide to the expression of Uncertainty in Measurement) approach using the law of propagation of uncertainty. A reference pressure standard NPLI-4 was cross-floated against our pneumatic primary pressure standard NPLI-10, which is a large diameter piston gauge. The MCM was used for the simulated estimation. A good agreement is observed between the two methodologies, and the results are discussed in detail.
  PubDate: 2018-11-26
  DOI: 10.1007/s00769-018-1355-3
Congresses, conferences, workshops and courses
- PubDate: 2018-11-17
  DOI: 10.1007/s00769-018-1361-5
Effect of irradiation for sterilization on beverage reference materials
for the analysis of food additives
- Authors: Seonghee Ahn; Byungjoo Kim
  Abstract: Reference materials for proficiency testing (PT) were prepared for 6 years. The target analytes were food additives, sorbic acid, benzoic acid, and propyl p-hydroxybenzoate, in two kinds of commercial beverages. To enhance the stability of PT reference materials, a sterilization step was employed in the procedure of preparation. However, when beverage reference materials were irradiated with gamma rays (γ-rays), the irradiation affected sorbic acid and benzoic acid, and the mass fractions of the analytes changed. In addition, the target analytes in a beverage containing many ingredients were less affected by irradiation than those in a beverage containing simple ingredients. To avoid the changes and the variation of the mass fraction of target analytes, propionic acid was used as an antibacterial agent instead of irradiation. The result was that the reference materials remained stable. The propionic acid preserved the matrices of the beverage reference materials and did not affect the mass fraction of the target analytes by the end of the PT program.
  PubDate: 2018-11-17
  DOI: 10.1007/s00769-018-1359-z
Competency evaluation on electrolytic conductivity measurement in
Indonesia by an unofficial bilateral comparison between RCChem-LIPI and
NIMT
- Authors: Fransiska Sri Herwahyu Krismastuti; Sujarwo Sujarwo; Ayu Hindayani; Nuryatini Hamim; Nongluck Tangpaisarnkul; Wiphada Hongthani
  Abstract: The Research Centre for Chemistry—Indonesian Institute of Sciences (RCChem-LIPI) organized an unofficial bilateral comparison on electrolytic conductivity with the Electrochemistry Laboratory—National Institute of Metrology Thailand (NIMT). The electrochemical laboratory RCChem-LIPI, as a Designated Institute for Chemical Metrology in Indonesia, started to develop the secondary method on electrolytic conductivity measurement in 2016. Therefore, the purpose of this unofficial bilateral comparison was to test the ability of RCChem-LIPI laboratory and see the capacity building progress in doing the conductivity measurement. There were two samples containing potassium chloride prepared by RCChem-LIPI, and both samples had the electrolytic conductivity value in the range of 1000 µS cm−1 to 20000 µS cm−1. The samples were sent to NIMT and then measured at the same time duration. The results were compared, analyzed and evaluated based on their assigned values. The assigned values were 15309 µS cm−1 and 6650 µS cm−1 for samples A and B, respectively. The deviation for each measurement result was determined, and the uncertainties were also calculated from the data reported by both laboratories. The data evaluation and analysis confirm that the measurement results for both participant laboratories were in agreement with the assigned value of this unofficial bilateral comparison.
  PubDate: 2018-11-16
  DOI: 10.1007/s00769-018-1360-6
A proficiency testing scheme to evaluate the effectiveness of laboratory
sample reduction of a soil sample
- Authors: Ken Middlebrook
  Abstract: Although proficiency testing (PT) schemes in analytical chemistry are intended to test the entire analytical process, the reality is that some aspects of the analytical process are often excluded from this evaluation. This paper will describe an approach to PT that is being employed by the Canadian Association for Laboratory Accreditation designed to test specific aspects of the analytical process that are not typically addressed. The example detailed describes a PT study that was designed to test the ability of participants to obtain a representative test sample from a laboratory sample that was intentionally prepared to have good between-sample homogeneity but poor within-sample homogeneity.
  PubDate: 2018-11-09
  DOI: 10.1007/s00769-018-1357-1
Proficiency testing as an instrument to assess the analytical performance
and the methods routinely implemented: the Italian experience for the
screening of antibiotic residues in milk in the official control
- Authors: Anna Maria Ferrini; Brunella Appicciafuoco; Maria Rosa Massaro; Fabio Galati; Marina Patriarca
  Abstract: The present work describes the outcome of the second proficiency test (PT) for the routine screening of antibiotic residues in milk, organized in 2016, for the Official Control Laboratories by the National Reference Laboratory (NRL) for veterinary antimicrobial residues in food of animal origin (ISS, Italy). Besides assessing the overall laboratories’ performance, this PT aimed to update the information concerning the screening methods used at the national level and focused, in particular, on the Official Control Laboratories performance for the detection of tetracyclines. This last feature intended to tackle the strong criticalities observed in the first PT, organized by the NRL in 2012, and to monitor the consequent implementation of relevant corrective actions. Thirty-one Official Control Laboratories joined the 2016 PT. They received five lyophilized milk samples, one negative and four positive for benzylpenicillin (PEN), sulphadiazine (SDZ) and oxytetracycline (OXY) to be reconstituted to the final concentrations of 1×MRL for PEN and SDZ and 2.5× and 4×MRL, respectively, for OXY. In addition, only for OXY, the protocol required the preparation by dilution of two additional samples at the final concentrations of 2× and 1×MRL. Overall the laboratories’ performance was satisfactory. However, for OXY, although a reduction in the percentage of false negative results was observed, as compared to the first PT, the majority of laboratories had not yet implemented complementary methods to respond to the criticality previously signalled. One more time the organization of a dedicated PT proved to be an effective means to provide objective indicators of the state of the art in a specific area of testing.
  PubDate: 2018-11-09
  DOI: 10.1007/s00769-018-1352-6
Understanding the problems in pharmaceutical procurement with special
reference to active pharmaceutical ingredients and excipients
- Authors: Zauwad Alam; Sukhbir Kaur; Pawan Kumar Porwal
  Abstract: Procurement of raw materials, key intermediates and excipients for the preparation of finished pharmaceutical preparation is considered to be complex process which involve multiple channels and require skilled personnel and proper validation. This review attempts, in relatively brief compass to provide an account of the problems that arise while procurement of active pharmaceutical ingredient (API) and excipients in pharmaceutical industry. This review has been structured with specified as well as generalized problems raised up during procurement of API and other material in pharmaceutical industry. Lack of proper regulatory requirements and unbiased market information with the absence of a comprehensive procurement policy is the major factor which creates complications while procurement. Besides these, lack of properly designed user requirement specifications (URS) which ultimately affect quality and delivery of quoted material. An 8-Question-based approach has been proposed to design URS, other approaches for material procurement and supplier qualification have been discussed, and a vendor certification procedure is presented.
  PubDate: 2018-11-09
  DOI: 10.1007/s00769-018-1344-6
LC–ELISA as a contribution to the assessment of matrix effects with
environmental water samples in an immunoassay for estrone (E1)
- Authors: Holger Hoffmann; Christian Knizia; Maren Kuhne; Ulrich Panne; Rudolf J. Schneider
  Abstract: Estrone (E1), a metabolite of the estrogenic hormones 17β-estradiol (β-E2) and 17α-estradiol (α-E2), is itself a potent estrogen which can have a significant impact on the hormonal balance. Due to its high potential for adverse effects on human health and aquatic life even at pg/L to ng/L levels, its appearance in water should be monitored. E1 has also been considered a marker substance for the presence of other estrogens. This study presents a newly developed direct competitive enzyme-linked immunosorbent assay (ELISA) for quantification of E1 in environmental water samples using new monoclonal antibodies. The quantification range of the ELISA is 0.15 µg/L to 8.7 µg/L E1, and the limit of detection is around 60 ng/L for not pre-concentrated water samples. A pre-concentration step after careful selection of suitable phases for SPE was developed, too. The influence of organic solvents and natural organic matter on the ELISA was assessed. The high selectivity of the monoclonal antibody was demonstrated by determining the cross-reactivity against 20 structurally related compounds. For the assessment of matrix effects, a concept (“LC–ELISA”) is thoroughly exploited, i.e., separating complex samples by HPLC into 0.3 min fractions and determination of the apparent E1 concentration. Furthermore, fractions with interferences for nontarget/suspected-target analysis can be assigned. A dilution approach was applied to distinguish between specific interferences (cross-reactants) and non-specific interferences (matrix effects). In the determination of 18 environmental samples, a good agreement of the E1 concentration in the respective fractions was obtained with mean recoveries of 103 % to 132 % comparing ELISA to LC–MS/MS. Graphical abstract
  PubDate: 2018-11-09
  DOI: 10.1007/s00769-018-1351-7
Combining UK and German emissions monitoring proficiency testing data
based on stack simulator facilities to determine whether increasingly
stringent EU emission limits are enforceable
- Authors: Marc D. Coleman; Thomas O. M. Smith; Rod A. Robinson; Benno Stoffels; Dominik Wildanger
  Abstract: We report an examination of the capability of the existing measurement infrastructure in the industrial emissions sector for successfully enforcing emission limits across three generations of legislation: the Waste Incineration Directive and Large Combustion Plant Directive (WID and LCPD); the Industrial Emissions Directive (IED) which superseded the aforementioned directives in 2013; the Waste Incineration and Large Combustion Plant Best Available Technique Reference documents (BREFs) where the former is currently at the draft stage (WI BREF and LCP BREF). The significant volume of proficiency testing data based on semi-tech stack simulator facilities operated by the National Physical Laboratory in the UK and the Hessian Agency for Nature Conservation, Environment and Geology in Germany were combined into a unique database. The emission species considered and their associated standard reference methods (SRMs) were: CO EN 15058; NOx (NO + NO2) EN 14792; total organic carbon EN 12619; total dust EN 13284-1. Collectively analysing participant distributions from 2002 to 2015, it was found that emission limits: under the WID and LCPD could be enforced (the directives for which the SRMs were originally designed); under the IED could in principle be enforced; under the WI BREF and LCP BREF would struggle to be enforced. This evidenced the need for improvements in the existing measurement infrastructure, without which test laboratories would struggle to provide the data quality needed by process plant operators for reporting into national emission inventories, and for national regulators who are legally responsible for enforcing emission limits aimed at improving European health and environmental impact.
  PubDate: 2018-11-09
  DOI: 10.1007/s00769-018-1354-4
External quality assessment of point-of-care CD4 testing in Thailand and
Southeast Asia
- Authors: Egarit Noulsri; Surada Lerdwana; Kovit Pattanapanyasat
  Abstract: In recent years, the use of point-of-care (POC) CD4 testing technologies has increased dramatically in Thailand and other Southeast Asian (SEA) countries. However, no data regarding external quality assessment of these POC CD4 testing technologies have been reported. The current study aimed to evaluate the performance of POC CD4 testing technologies, including BD FACSPresto, CyFlow, Guava, Muse, and PIMA, used in the participating laboratories in Thailand, Myanmar, Laos, Indonesia, and Nepal from 2014 to 2017. The results showed a trend toward an increasing number of participating laboratories using POC CD4 testing technologies between trial numbers 73 and 90. In the laboratories participating in the study, CyFlow technologies were the most used POC CD4 testing technologies. In addition, a trend of decreasing coefficients of variation (%CVs) was demonstrated across the trials, and the final trial showed an overall %CV of 14 %. In trial numbers 73 and 77, 57 % and 68 % of measurements showed standard deviation index (SDI) values ranging between − 1 and + 1. In trial numbers 80 and 90, the proportion of measurements with SDI values ranging between − 1 and + 1 had increased to 100 % and 72 %. These results suggest an improvement in POC CD4 testing in Thailand and other SEA countries.
  PubDate: 2018-11-02
  DOI: 10.1007/s00769-018-1358-0
Identification of prion protein genotype in sheep: 11 years of
proficiency tests in Italy
- Authors: Barbara Chiappini; Gaia Scavia; Michela Conte; Luisella Morelli; Maria Gabriella Perrotta; Umberto Agrimi; Gabriele Vaccari
  Abstract: Scrapie of sheep belongs to a group of fatal neurodegenerative diseases known as prion diseases. Scrapie is a naturally transmissible disease and sheep susceptibility is highly dependent on the host prion protein (PrP) genotype. On this basis, the European Union has established management strategies of scrapie in sheep population, to be achieved by an ad hoc breeding programme to increase the genetic resistance of the ovine population and by selective culling, both based upon the PrP genotyping. The Istituto Superiore di Sanità, appointed by the Italian Ministry of Health as the Reference Laboratory for PrP genotyping, has since 2005 organised proficiency tests (PTs) for sheep PrP genotype identification. The PT aims at assessing the accuracy of the genetic analysis performed by the laboratories involved in official control at national level. From 2005 to 2016, 12 laboratories on average participated to nine PT rounds. The overall analytical performance was satisfactory with few laboratories reporting errors in PrP genotype identification. A total of 22 errors including sixteen analytical and six formal errors were identified out of 2650 results reported (0.8 %). The number of laboratories reporting 100 % correct results increased over the years although no statistical trend could be observed. The low number of laboratories failing the PT revealed an overall good technical capability and skills of laboratories and technicians in performing the genetic analysis. This is highly important since the availability of an efficient laboratory network is crucial for the implementation and management of scrapie control plan at national level.
  PubDate: 2018-10-27
  DOI: 10.1007/s00769-018-1356-2
Standard addition method with cumulative spikes: uric acid determination
in human serum by voltammetry with optimized uncertainty
- Authors: Tony R. L. Dadamos; Airton J. Damaceno; Fernando L. Fertonani; Ricardo J. N. B. Silva
  Abstract: This work presents a low-cost, simple and adequately reliable voltammetric alternative to the determination of uric acid (UA) in human serum by the enzymatic colorimetric standard method. UA is an organic molecule of great biomedical interest since its level is used in the diagnosis of several diseases. The quality of the electrochemical measurements was evaluated by comparing their expanded uncertainty with a target (i.e. maximum admissible) value of 0.56 mg dL−1 (one eighth of UA ranges of healthy individuals) and by analysing spiked serum and human serum samples measured by the standard method. The modified working electrode has 25 % lignin, 60 % nanocarbon, 15 % mineral oil and a copper electrodeposit. Due to the vulnerability of voltammetric techniques to matrix effects and to the small amount of serum samples, it is used the standard addition method with cumulative analyte additions for electrode calibration. The measurement uncertainty was estimated by the “bottom-up” approach where uncertainty components were combined using either the uncertainty propagation law or the numerical Kragten method. The analytical procedure was successfully applied to the analysis of physiological serums spiked at 1.0 mg dL−1, 3.0 mg dL−1, 5.0 mg dL−1, 7.0 mg dL−1 or 9.0 mg dL−1 of UA and two human serum samples. The results of analysed serums estimated by the voltammetric procedure have adequately low uncertainty and are metrologically equivalent (i.e. compatible) to the reference values estimated by the spiking process or by the standard method. Therefore, the developed voltammetric measurement procedure is a promising alternative to the standard procedure.
  PubDate: 2018-10-27
  DOI: 10.1007/s00769-018-1350-8
Validation of new methodology for the definition of tolerance limits of
critical properties in fuels handled in terminals and
pipelines—giveaway: compliance with the specification
- Authors: Elcio Cruz de Oliveira; Lúcio Abdala de Santana Maia; Lívio Garcia da Costa; Túlio Campos Lourenço
  Abstract: In any commercial transaction, the presence of tolerances from specification limits is essential to ensure that the true value of the property of interest is sufficiently close to the specification value with a mutually agreed probability, so that there is no litigation between the parties. In order to meet this requirement, this tolerance is treated elegantly as a “toast” or more technically as a superior quality that the customer receives—giveaway. This work presents a new methodology for determining the tolerance limits of critical properties in some fuels, based on the reproducibility, on the difference between the averages of all acceptable results of each laboratory and on the specifications derived from the Brazilian National Agency for Oil, Natural Gas and Biofuels. Applying this approach to flash point by tag closed, final boiling point, volatility (95 % evaporated temperature), electrical conductivity and total sulfur content of some fuels and by means of a hypothesis test, the results show that this methodology was validated for most of the proposed new limits.
  PubDate: 2018-10-23
  DOI: 10.1007/s00769-018-1353-5
Cooperation in publicly funded reference material production
- Authors: Håkan Emteborg; Doris Florian; Steven Choquette; Stephen L. R. Ellison; Maria Fernandes-Whaley; Lindsey Mackay; Pearse McCarron; Ulrich Panne; Sylvia G. Sander; Sook-Kyung Kim; Andrea Held; Thomas Linsinger; Stefanie Trapmann
  PubDate: 2018-10-12
  DOI: 10.1007/s00769-018-1349-1
Provision of proficiency testing for histamine mass fraction in canned
tuna to improve the capability of chemical laboratories in the Philippines
- Authors: Benilda S. Ebarvia; Aaron Dacuya; Sharlene R. Cabanilla; Natividad R. Mamplata
  Abstract: In this work, two reference materials (RMs) for mass fraction of histamine in canned tuna were developed to address the need of local testing laboratories for matrix RMs and a PT scheme for histamine. A validated method using HPLC with fluorescence detector (340 nm for excitation and 445 nm for emission) was applied with post-column derivatization for the RM’s homogeneity and stability studies. Acceptable results were obtained after statistical evaluation of homogeneity and stability according to IUPAC Harmonized Protocol and ISO Guide 35, respectively. Two PT exercises for histamine determination based on ISO/IEC 17043 were organized in 2014 and 2015 with the assigned values of 148 and 65 mg/kg, respectively. These reference values were obtained using exact matching liquid chromatography–isotope dilution mass spectrometry (LC–IDMS) with gravimetric sample preparation. The corresponding uncertainty of the reference value was obtained by ISO GUM approach where the characterization of the sample gave the highest contribution (41 %). The satisfactory z-score performance evaluated from the 12 laboratories was 50 % and 58.3 % in the first and second PT round, respectively. Most of the laboratories used AOAC Official Method 977.13 but not all conducted method validation. The 50 % decrease in unsatisfactory results in the second PT round is a significant improvement in the local laboratory performance for histamine analysis. However, the provision of more PT schemes and the increased use of CRMs in the future are still needed by these laboratories for external quality assurance and method validation to enhance the present capability.
  PubDate: 2018-10-09
  DOI: 10.1007/s00769-018-1347-3
Innovative reference material for improving the quality control in the
sucroenergetic sector
- Authors: Maria I. V. Martínez; Rolf Zeisler; Elisabete A. De Nadai Fernandes; Márcio A. Bacchi
  Abstract: Analytical techniques in the sucroenergetic sector can now for the first time be supported by an innovative matrix-matching reference material produced from sugarcane leaves. This will further enhance the validity of the measurement results and contribute significantly to the quality assurance of plant nutrition analysis. The candidate reference material obtained had a low residual moisture and appropriate particle size. Neutron activation analysis was used to determine the mass fraction of Al, Br, Ca, Cl, Ce, Co, Cs, Cu, Fe, Hf, K, La, Mg, Mn, Mo, Na, P, Rb, Sb, Sc, Sm, Sr, Th, V and Zn, and the Kjeldahl method for N. Statistical techniques were applied to evaluate minimum sample mass and within-bottle homogeneity (ANOVA, Tukey test and PCA) and between-bottles homogeneity (ANOVA). It is demonstrated in this paper that the material is homogeneous using 50 mg mass sample for most chemical elements. However, sample masses of 200 mg or greater are required for Co, Na, Sb and V.
  PubDate: 2018-10-03
  DOI: 10.1007/s00769-018-1348-2