A New Robust Top-Down Method for Measurement Uncertainty Estimation of the ED(P)- XRFS Outcomes Carried on a Fluorescence Glass

The rare earths doped glasses have been considered as the best solution to fulfil the increasing demand for cheaper fluorescent taggants. The ensuring a high quality of a spectral taggant batch imposes, among others, an exact chemical composition measurement. The most convenient method for elemental analysis of powdered specimens is Energy Dispersive (Polarised)- X-ray Fluorescence Spectroscopy (ED(P)-XRFS) because it has many advantages: non-destructive, large analytical range, robustness, easy sample preparation, cheaper consumables, less time consuming etc. ED(P)-XRFS has some inherent analytical drawbacks such as: interelements interferences, matrix dependence etc. The only way to overcome the drawbacks is a proper method for the measurement uncertainty (MU) estimation of the outcomes. Consequently, the paper argues that the bottom-up method for MU estimation is feeble as long as the sensitivity coefficients of the factors of uncertainty budget are not well known and documented, which is the habitual case of the ED and WD XRFS bottom-up published methods. The paper substantiates a new robust top-down method for MU estimation of the ED(P)-XRFS outcomes carried on a fluorescence glass. Also, the paper presents a representative case study of appliance of the developed top-down method. The other novelties addressed in the paper are: i. Introducing the robust statistics as further checks for the accuracy of mean and of standard deviation, according to ISO 13583:2015; ii. A new criterion for testing the normal distribution of the mean of a set of fewer outcomes based on Central Limit Theorem and on the central momentum of third orde; iii. The method was implemented for multiple simultaneous outcomes. The top-down method, given in the paper, can be applied to ED- and WD-XRFS routine measurements in industrial laboratories or in material science ones, but it can be adapted, without much effort, to other types of tests e.g. hardness, XRD etc.

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Comparison between bottom-up and top-down approaches in the estimation of measurement uncertainty

Clinical Chemistry and Laboratory Medicine (CCLM) ◽

10.1515/cclm-2014-0801 ◽

2015 ◽

Vol 53 (7) ◽

Cited By ~ 12

Author(s):

Jun Hyung Lee ◽

Jee-Hye Choi ◽

Jae Saeng Youn ◽

Young Joo Cha ◽

Woonheung Song ◽

...

Keyword(s):

Measurement Uncertainty ◽

Uncertainty Budget ◽

Internal Quality ◽

Systematic Bias ◽

Top Down ◽

Bottom Up ◽

Sources Of Uncertainty ◽

Clinical Laboratories ◽

Measurement Results ◽

Low Glucose

AbstractMeasurement uncertainty is a metrological concept to quantify the variability of measurement results. There are two approaches to estimate measurement uncertainty. In this study, we sought to provide practical and detailed examples of the two approaches and compare the bottom-up and top-down approaches to estimating measurement uncertainty.We estimated measurement uncertainty of the concentration of glucose according to CLSI EP29-A guideline. Two different approaches were used. First, we performed a bottom-up approach. We identified the sources of uncertainty and made an uncertainty budget and assessed the measurement functions. We determined the uncertainties of each element and combined them. Second, we performed a top-down approach using internal quality control (IQC) data for 6 months. Then, we estimated and corrected systematic bias using certified reference material of glucose (NIST SRM 965b).The expanded uncertainties at the low glucose concentration (5.57 mmol/L) by the bottom-up approach and top-down approaches were ±0.18 mmol/L and ±0.17 mmol/L, respectively (allWe presented practical and detailed examples for estimating measurement uncertainty by the two approaches. The uncertainties by the bottom-up approach were quite similar to those by the top-down approach. Thus, we demonstrated that the two approaches were approximately equivalent and interchangeable and concluded that clinical laboratories could determine measurement uncertainty by the simpler top-down approach.

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REASSESSMENT OF UNCERTAINTY EXPANSION BY LINEAR ADDITION OF LONG-TERM COMPONENTS FROM TOP-DOWN INFORMATION

Radiocarbon ◽

10.1017/rdc.2021.96 ◽

2021 ◽

pp. 1-15

Author(s):

G Salazar ◽

S Szidat

Keyword(s):

Mass Spectrometry ◽

Measurement Uncertainty ◽

High Precision ◽

Accelerator Mass Spectrometry ◽

Expanded Uncertainty ◽

Top Down ◽

Bottom Up ◽

Linear Addition

ABSTRACT Since radiocarbon accelerator mass spectrometry (14C AMS) is considered a high-precision technique, reassessment of the measurement uncertainty has been a topic of interest. Scientists from analytical and metrological fields have developed the top-down and bottom-up measurement of uncertainty approaches. The 14C quoted error should approximate the uncertainty of long-term repetitions of the top-down approach in order to be realistic. The novelty of this paper is that the uncertainty of both approaches were approximated to each other. Furthermore, we apportioned the graphitization, instrumentation, and bias components in order to additively expand the quoted error. Our results are comparable to error multipliers and to long-term repeatability studies reported by other laboratories. Our laboratory was established in late 2012 with N2 as stripper gas and 7 years later, we changed to helium stripper. Thus, we were able to compare both gases, and demonstrate that helium is a better stripper gas. In absolute F14C units, the ranges of graphitization+bias combined uncertainties were (0.7 to 4.1) × 10–3 for N2 and (0.7–3.0) × 10–3 for He depending on the standard 14C content. The error multiplier for He defined as the expanded uncertainty over quoted error, in average, was 1.7; while without the bias, the multiplier was 1.3.

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Top-down and bottom-up approaches for the estimation of measurement uncertainty in coagulation assays

Clinical Chemistry and Laboratory Medicine (CCLM) ◽

10.1515/cclm-2020-0038 ◽

2020 ◽

Vol 58 (9) ◽

pp. 1525-1533 ◽

Cited By ~ 1

Author(s):

Yong Kwan Lim ◽

Oh Joo Kweon ◽

Mi-Kyung Lee ◽

Bohyun Kim ◽

Hye Ryoun Kim

Keyword(s):

Measurement Uncertainty ◽

International Normalized Ratio ◽

International Standards ◽

Factor V ◽

Top Down ◽

Bottom Up ◽

International Guidelines ◽

Coagulation Assays ◽

Clinical Laboratories ◽

Comparison Results

AbstractBackgroundThe assessment of measurement uncertainty (MU) in clinical laboratories is essential to the reliable interpretation of results in clinical laboratories. However, despite the introduction of various methods for the expression of uncertainty in measurement, the MUs of coagulation tests have not been extensively studied. The aim of this study was to quantify the MU of various coagulation assays according to international guidelines and to report an expected confidence in the quality of coagulation assays.MethodsWe selected activated partial thromboplastin time, international normalized ratio (INR), protein C/S, antithrombin, fibrinogen, and Factor V/VIII/X to quantify the MUs of two coagulation testing systems: ACL TOP 750 CTS (Instrumentation Laboratory, Bedford, MA, USA) and STA Compact (Diagnostica Stago, Asnières-sur-Seine, France). We used international standards and interlaboratory comparison results in accordance with international guidelines in a top-down approach to the assessment of MU. For INR, MU was estimated in a bottom-up approach using reference thromboplastin and certified plasmas.ResultsTop-down approaches resulted in MUs between 3.3% and 21.3% for each measurand. In the bottom-up approach, MUs of INR values ranged from 10.9% to 26.4% and showed an upward trend as INR increased.ConclusionsIn this study, we were successful in quantifying MU of coagulation assays using practical methods. Our results demonstrated that top-down and bottom-up approaches were adequate for coagulation assays. However, some assays showed significant biases against international standards; therefore, standardization would be necessary to ensure more reliable patient results.

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Measurement uncertainty and metrological traceability of whole blood cyclosporin A mass concentration results obtained by UHPLC-MS/MS

Clinical Chemistry and Laboratory Medicine (CCLM) ◽

10.1515/cclm-2018-0120 ◽

2018 ◽

Vol 56 (9) ◽

pp. 1458-1468 ◽

Cited By ~ 1

Author(s):

Raül Rigo-Bonnin ◽

Pedro Alía ◽

Francesca Canalias

Keyword(s):

Measurement Uncertainty ◽

Whole Blood ◽

Mass Concentration ◽

High Performance ◽

Metrological Traceability ◽

Top Down ◽

Bottom Up ◽

Clinical Laboratories ◽

Liquid Chromatography Tandem Mass ◽

Mass Concentrations

Abstract Background: Traceable and accurate results of cyclosporine A (CsA) mass concentrations in whole blood are required to ensure the monitoring of immunosuppressive therapy in transplant recipients. Metrological traceability and measurement uncertainty can allow ensuring reliability and comparability of these results over time and space. In this study, we provide a practical and detailed example of how the traceability and uncertainty of mass concentration of CsA results, obtained using an ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) procedure, can be described and estimated. Methods: Traceability was described mainly according to ISO 17511 and information obtained from certificates facilitated with the manufacturer’s calibrators. Uncertainty estimation was performed using the bottom-up and top-down approaches. For the bottom-up approach, the most relevant sources of uncertainty were identified and later used to estimate the standard, combined and expanded uncertainties. For the top-down approach, expanded uncertainty was estimated directly using intralab quality control data mainly. Results: Mass concentration of CsA results was traceable to the manufacturer’s product calibrators used to calibrate the UHPLC-MS/MS procedure. The expanded uncertainties estimated by the bottom-up and top-down approaches were 7.4% and 7.2%, respectively. Conclusions: After performing the bottom-up and top-down approaches, we observed that their results were quite similar. This fact would confirm that the top-down approach could be sufficient for estimating uncertainty of CsA mass concentrations in whole blood results in clinical laboratories. Finally, we hope that this study can help and motivate clinical laboratories to describe metrological traceability and to perform measurement uncertainty studies based on the simpler top-down approach.

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