Multicenter evaluation of the commutability of a potential reference material for harmonization of enzyme activities

2004 ◽  
Vol 42 (12) ◽  
Author(s):  
Volkher Scharnhorst ◽  
Joke Apperloo ◽  
Henk Baadenhuijsen ◽  
Huib L. Vader
Keyword(s):  
Reference Material ◽  
Reference Materials ◽  
Enzyme Activities ◽  
Regression Line ◽  
Reference Intervals ◽  
Correction Factors ◽  
Serum Samples ◽  
Field Methods ◽  
Common Reference ◽  
Fold Reduction

AbstractStandardization of laboratory results allows for the use of common reference intervals and can be achieved via calibration of field methods with secondary reference materials. These harmonization materials should be commutable, i.e., they produce identical numerical results independent of assay principle or platform. This study assessed the commutability of a cryolyoprotectant-containing harmonization material, obtained from the Dutch Foundation for Quality Assessment in Clinical Laboratories, that is intended to harmonize measurements of enzyme activities within the Dutch project “Calibration 2000”. The catalytic concentrations of alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, γ-glutamyltransferase and creatine kinase were analyzed in pooled patient sera and in the reference material in 14 laboratories. On liquid chemistry analyzers the harmonization material behaves like patient material. The enzyme activities measured in it fall on the regression lines calculated from activities measured in serum samples. For dry chemistry analyzers the activities of all enzymes measured in the harmonizator differ from the serum-based regression line. We show that this is due to the sucrose-containing cryolyoprotectant in the harmonization material. For each enzyme, correction factors were calculated that compensated for the bias and proved to be constant between reagent lots. Depending on the enzyme activity measured, application of these factors leads to 2- to 10-fold reduction of between-laboratory percentage coefficient of variation. Thus, additives to (potential) reference materials may alter their matrix in a way that interferes with analysis on certain test systems. The bias caused may be quantifiable and correctable. Establishment of correction factors leads to analytical uncertainties and costs. Therefore, matrix-based materials without additives should be selected as reference materials.

Effects of lyophilization of serum on the measurement of apolipoproteins A-I and B

1990 ◽  
Vol 36 (2) ◽  
pp. 366-369 ◽  
Author(s):  
S M Marcovina ◽  
J L Adolphson ◽  
M Parlavecchia ◽  
J J Albers
Keyword(s):  
Reference Materials ◽  
Apolipoprotein B ◽  
Matrix Effects ◽  
Reference Intervals ◽  
Assay Method ◽  
Common Reference ◽  
Apolipoprotein A ◽  
Quality Control Materials ◽  
Standardization Process ◽  
The Difference

Abstract A common accuracy-based standardization program is indispensable for establishing reference intervals for the clinical use of apolipoproteins. The development and distribution of reference materials and quality-control materials that do not exhibit matrix effects between methods is essential to the standardization process. We examined the suitability of lyophilized material as a common reference material for the measurement of apolipoproteins A-I and B. We determined values for apolipoproteins A-I and B in frozen and lyophilized serum pools, using different immunochemical approaches. We found little or no differences in apolipoprotein A-I values between frozen and lyophilized pools as determined by the different methods. In contrast, values for apolipoprotein B in lyophilized samples were consistently lower than those obtained for frozen samples. After adjusting for the effect of dilution due to reconstitution, the difference in the apolipoprotein B values for lyophilized as compared with frozen samples ranged from -26% to 4%, depending upon the assay method. Evidently, serum pools in lyophilized from are not a suitable matrix for reference materials for apolipoprotein B measurements but can be used for apolipoprotein A-I measurements.

scholarly journals Commutability Assessment of Potential Reference Materials Using a Multicenter Split-Patient-Sample Between-Field-Methods (Twin-Study) Design: Study within the Framework of the Dutch Project “Calibration 2000”

2002 ◽  
Vol 48 (9) ◽  
pp. 1520-1525 ◽  
Author(s):  
Henk Baadenhuijsen ◽  
Herman Steigstra ◽  
Christa Cobbaert ◽  
Aldy Kuypers ◽  
Cas Weykamp ◽  
...  
Keyword(s):  
Study Design ◽  
Reference Materials ◽  
Twin Study ◽  
State Of The Art ◽  
Regression Line ◽  
Hdl Cholesterol ◽  
Field Methods ◽  
Patient Sample ◽  
Serum Pool ◽  
Alternative Approach

Abstract Background: The Dutch project “Calibration 2000” aims at harmonization of laboratory results via calibration by development of commutable, matrix-based, secondary reference materials. An alternative approach to the NCCLS EP14 protocol for studying commutability of reference materials is presented, the “twin-study design”, which in essence is a multicenter, split-patient-sample, between-field-methods protocol. Methods: The study consisted of the simultaneous analysis of fresh patient sera and potential reference materials (PRMs) for HDL-cholesterol (HDL-C) by 86 laboratories forming 43 laboratory couples. Six subgroups of method combinations were formed. The patient sera were selected and interchanged by each laboratory couple. The PRMs consisted of three types: C37, prepared according to the NCCLS C37 protocol; Fro, frozen selectively pooled human serum; and Lyo, which was the same serum pool as Fro but lyophilized in the presence of sucrose. All PRMs were provided in three HDL-C concentrations. The regression line residuals for the PRMs were normalized by expressing them as multiples of the state-of-the-art within laboratory SD (SDSA). In addition, the extra contribution of each PRM to the total measurement uncertainty, CVNetto, was calculated. Results: Averaged over the three PRM concentrations, 1.6% of the C37 residuals were outside the 3 SDSA limit. For the Fro and Lyo PRMs, these values were 2.4% and 11.1%. CVNetto values for C37, Fro, and Lyo were 2.9%, 4.3%, and 5.3%, respectively. Conclusions: The present twin-study design, as a practical alternative to the NCCLS EP14 protocol, is a viable way of studying commutability characteristics of PRMs. The study suggests that the C37 PRMs are the best candidates for a future reference material.

scholarly journals Global certified-reference-material- or reference-material-scaled nutrient gridded dataset GND13

2020 ◽  
Vol 12 (1) ◽  
pp. 487-499 ◽  
Author(s):  
Michio Aoyama
Keyword(s):  
Reference Material ◽  
Reference Materials ◽  
Certified Reference Materials ◽  
Global Ocean ◽  
Nutrient Concentrations ◽  
Correction Factors ◽  
Data Product ◽  
Gridded Dataset ◽  
Nutrient Analyses ◽  
Better Than

Abstract. A global nutrient gridded dataset that might be the basis for studies of more accurate spatial distributions of nutrients in the global ocean was created and named GND13. During 30 cruises, reference materials of nutrients in seawater or their equivalents were used at all stations, and high-precision measurements were made. The precision of the nutrient analyses was better than 0.2 %. Data were collected from the hydrographic cruises in the JASMTEC R/V Mirai cruises, JMA cruise, CARINA, PACIFICA, and WGHC datasets from which nutrient data were available. Analyses were conducted at 243 crossover stations. Cruises that used certified reference materials or reference materials (CRMs/RMs) for seawater nutrient concentration measurements were used as a reference of an unbroken chain of comparison to determine correction factors which made nutrient concentrations obtained by other cruises SI traceable. Dissolved oxygen was secondarily quality-controlled using the same methodology as was used to create the nutrient gridded data product, but, lacking a traceable standard, the resulting oxygen data product is not SI traceable. Finally, a dataset of nitrate, phosphate, and silicate concentrations was created at latitude and longitude intervals of 0.5∘ and on 136 isobaric surfaces to depths of 6500 m as an SI-traceable dataset. This dataset has already been published at: https://doi.org/10.17596/0000001 (Aoyama, 2017).

International Federation of Clinical Chemistry Standardization Project for Measurements of Apolipoproteins A-I and B. II. Evaluation and Selection of Candidate Reference Materials

1992 ◽  
Vol 38 (5) ◽  
pp. 658-662 ◽  
Author(s):  
J J Albers ◽  
S M Marcovina ◽  
H Kennedy
Keyword(s):  
Reference Materials ◽  
Clinical Chemistry ◽  
Collaborative Study ◽  
Second Phase ◽  
Serum Samples ◽  
Apo B ◽  
Common Reference ◽  
Test Systems ◽  
Serum Pool ◽  
Fresh Frozen

Abstract The first phase of an international collaborative study for standardization of test systems for measuring apolipoprotein (apo) A-I and apo B demonstrated that uniformity of apo A-I and apo B measurements can be achieved if suitable common reference materials are used to calibrate the different systems. The objective of the second phase was to evaluate the linearity and parallelism or proportionality of the candidate reference materials selected in phase one and to determine whether any of them could be proposed as international reference materials. We evaluated the proposed reference materials with 37 test systems for apo A-I and 38 for apo B, involving 23 manufacturers and five research laboratories. Two lyophilized preparations were proposed for apo A-I, SP1 from Behringwerke AG and SP2 from Daiichi Pure Chemicals Co., and two liquid preparations were proposed for apo B, SP3 from Behringwerke AG and SP4 from Reagents Applications. The linearity of the candidate reference materials was compared with the linearity of a frozen serum pool or interim serum reference material distributed to all the participants and with that of a fresh serum pool prepared by each participant. SP1 and SP3 exhibited linearity and parallelism similar to that of the fresh frozen serum pool and had among-laboratory CVs less than or similar to those obtained on normolipidemic serum samples (approximately 6% for apo A-I and approximately 7% for apo B).

Do we measure bilirubin correctly anno 2005?

2005 ◽  
Vol 43 (5) ◽  
Author(s):  
Joke J. Apperloo ◽  
Fedde van der Graaf ◽  
Volkher Scharnhorst ◽  
Huib L. Vader
Keyword(s):  
Reference Material ◽  
Human Serum ◽  
Reference Materials ◽  
Standard Reference Material ◽  
Total Bilirubin ◽  
Reference Method ◽  
Serum Samples ◽  
Suitable Material ◽  
Good Agreement

AbstractWe observed 30% discrepancy between liquid chemistry and dry chemistry analysers for the determination of total bilirubin in human adult serum samples, which were consistent with a 20% overestimation and 10% underestimation relative to a Jendrassik-Grof reference method, respectively. In contrast, standard reference material SRM916, which was recently recommended as being the most suitable material for attaining interlaboratory agreement, shows very good agreement on both types of analysers, as well as close to 100% recovery with respect to the reference method. We show that the liquid vs. dry bilirubin discrepancies seem to originate in the presence of either conjugated or δ-bilirubin. Our observations make it clear that good interlaboratory (or inter-analyser) agreement between bilirubin reference materials does not guarantee the same for bilirubin concentrations in human serum samples.

Proposal for guidelines to establish common biological reference intervals in large geographical areas for biochemical quantities measured frequently in serum and plasma

2004 ◽  
Vol 42 (7) ◽  
Author(s):  
Pål Rustad ◽  
Peter Felding ◽  
Ari Lahti
Keyword(s):  
Reference Materials ◽  
Standard Procedure ◽  
Reference Interval ◽  
Reference Intervals ◽  
Routine Method ◽  
Common Reference ◽  
Reference Samples ◽  
Project 2000

AbstractA suggestion for a standard procedure to establish biological reference intervals for biochemical quantities by a multicenter approach is presented. This procedure was developed for and used in the Nordic Reference Interval Project 2000 (NORIP). This project established biological reference intervals for 25 frequently requested biochemical quantities through cooperation of 102 Nordic laboratories. Each laboratory performed collection of reference samples and measurement using their routine methods. The bias of each routine method was eliminated by use of common reference materials measured in each of the participating laboratories.

scholarly journals The Importance of Commutability of Reference Materials Used as Calibrators: The Example of Ceruloplasmin

2013 ◽  
Vol 59 (9) ◽  
pp. 1322-1329 ◽  
Author(s):  
Ingrid Zegers ◽  
Robert Beetham ◽  
Thomas Keller ◽  
Joanna Sheldon ◽  
David Bullock ◽  
...  
Keyword(s):  
Reference Material ◽  
Quality Assessment ◽  
Reference Materials ◽  
External Quality Assessment ◽  
Serum Samples ◽  
External Quality ◽  
Measurement Results ◽  
Materials Used ◽  
The Uk ◽  
Good Linear Correlation

BACKGROUND Different methods for ceruloplasmin tend to give different results in external quality assessment schemes. During the production of the certified reference material ERM-DA470k/IFCC discrepant measurement results were also found for ceruloplasmin measured with different methods, and consequently the protein could not be certified in the material. METHODS We performed a commutability study with 30 serum samples and the reference materials ERM-DA470, ERM-DA470k/IFCC, and ERM-DA472/IFCC, using 6 different methods. Data were analyzed according to the CLSI Guideline C53-A to assess whether the reference materials had the same behavior as the serum samples with respect to measurement results obtained with combinations of the methods used. RESULTS Measurement results from different methods showed a good linear correlation for the serum samples. ERM-DA470 showed marked noncommutability for certain combinations of methods. ERM-DA470k/IFCC and ERM-DA472/IFCC were commutable for more combinations of methods. The lack of commutability of ERM-DA470 for certain combinations of methods correlates with results from the UK National External Quality Assessment Service showing discrepancies between results from these methods. For serum stored in the presence of sodium azide the results from different methods are essentially equivalent. CONCLUSIONS Ceruloplasmin in ERM-DA470 is a fully documented example of a situation in which, due to lack of commutability, the use of a common material for calibration did not lead to harmonization .

ICP-MS AND ICP-AES ANALYSIS OF PLANT REFERENCE MATERIALS

2019 ◽  
Vol 85 (6) ◽  
pp. 11-24
Author(s):  
I. V. Nikolaeva ◽  
A. A. Kravchenko ◽  
S. V. Palessky ◽  
S. V. Nechepurenko ◽  
D. V. Semenova
Keyword(s):  
Reference Material ◽  
Mass Spectrometer ◽  
Reference Materials ◽  
Atomic Emission ◽  
Icp Ms ◽  
Lithium Metaborate ◽  
Relative Standard ◽  
Microwave System ◽  
Total Analysis ◽  
Siberian Pine

Two methods — ICP-MS and ICP-AES are used for certification of the new reference material — needles of Siberian pine (NSP-1). Techniques of the analysis include decomposition of plant samples in two different ways: acid digestion in a microwave system MARS-5 and lithium metaborate fusion followed by ICP-MS and ICP-AES analysis of the solutions. Simultaneous determinations of all the elements were carried out in low, medium and high resolution using SF-mass-spectrometer ELEMENT and atomic-emission spectrometer IRIS Advantage with external calibrations and internal standards (In — ICP-MS, Sc —ICP-AES). Middle and high resolutions of ICP mass spectrometer were used for interference corrections. Data obtained by ICP-MS and ICP-AES with different decomposition techniques are in good agreement. The ICP-MS and ICP-AES techniques have been validated by the analysis of three plant reference materials: LB-1 (leaf of a birch), Tr-1 (grass mixture) and EK-1 (Canadian pondweed). These techniques were used for the determination of 38 elements in the new reference material NSP-1. Relative standard deviations for most of the determined elements were below 10%. Combination of ICP-MS and ICP-AES techniques for certification of the new reference material makes it possible to expand the set of elements to be determined and to reduce the total analysis time.

scholarly journals Development and certification of a reference material for zearalenone in maize germ oil

2021 ◽  
Author(s):  
Juliane Riedel ◽  
Sebastian Recknagel ◽  
Diana Sassenroth ◽  
Tatjana Mauch ◽  
Sabine Buttler ◽  
...  
Keyword(s):  
Reference Material ◽  
Reference Materials ◽  
Mass Fraction ◽  
High Performance ◽  
Certified Reference Materials ◽  
Maximum Level ◽  
Whole Process ◽  
Commission Regulation ◽  
Maize Oil ◽  
Maize Germ

AbstractZearalenone (ZEN), an estrogenic mycotoxin produced by several species of Fusarium fungi, is a common contaminant of cereal-based food worldwide. Due to frequent occurrences associated with high levels of ZEN, maize oil is a particular source of exposure. Although a European maximum level for ZEN in maize oil exists according to Commission Regulation (EC) No. 1126/2007 along with a newly developed international standard method for analysis, certified reference materials (CRM) are still not available. To overcome this lack, the first CRM for the determination of ZEN in contaminated maize germ oil (ERM®-BC715) was developed in the frame of a European Reference Materials (ERM®) project according to the requirements of ISO Guide 35. The whole process of CRM development including preparation, homogeneity and stability studies, and value assignment is presented. The assignment of the certified mass fraction was based upon an in-house study using high-performance liquid chromatography isotope dilution tandem mass spectrometry. Simultaneously, to support the in-house certification study, an interlaboratory comparison study was conducted with 13 expert laboratories using different analytical methods. The certified mass fraction and expanded uncertainty (k = 2) of ERM®-BC715 (362 ± 22) μg kg−1 ZEN are traceable to the SI. This reference material is intended for analytical quality control and contributes to the improvement of consumer protection and food safety. Graphical abstract

scholarly journals Biological variation and reference change value data for serum copper, zinc and selenium in Turkish adult population

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ceylan Bal ◽  
Serpil Erdogan ◽  
Gamze Gök ◽  
Cemil Nural ◽  
Betül Özbek ◽  
...  
Keyword(s):  
Adult Population ◽  
Reference Intervals ◽  
Serum Copper ◽  
Biological Variation ◽  
Serum Samples ◽  
Reference Change Value ◽  
Index Of Individuality ◽  
Copper Zinc ◽  
Clinically Significant ◽  
Analytical Variation

Abstract Objectives Calculation of biological variation (BV) components is very important in evaluating whether a test result is clinically significant. The aim of this study is to analyze BV components for copper, zinc and selenium in a cohort of healthy Turkish participants. Methods A total of 10 serum samples were collected from each of the 15 healthy individuals (nine female, six male), once a week, during 10 weeks. Copper, zinc and selenium levels were analyzed by atomic absorption spectrometer. BV parameters were calculated with the approach suggested by Fraser. Results Analytical variation (CVA), within-subject BV (CVI), between-subject BV (CVG) values were 8.4, 7.1 and 4.3 for copper; 4.2, 9.1 and 13.7 for zinc; 7.6, 2.5 and 6.9 for selenium, respectively. Reference change values (RCV) were 30.46, 27.56 and 22.16% for copper, zinc and selenium, respectively. The index of individuality (II) values were 1.65, 0.66 and 0.36 for copper, zinc and selenium, respectively. Conclusions According to the results of this study, traditional reference intervals can be used for copper but we do not recommend using it for zinc and selenium. We think that it would be more accurate to use RCV value for zinc and selenium in terms of following significant changes in recurrent results of a patient.

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