Estimation of the standard uncertainty of a calibration curve: application to sulfur mass concentration determination in fuels

2011 ◽  
Vol 17 (3) ◽  
pp. 275-281 ◽  
Author(s):  
Dimitrios Theodorou ◽  
Ypatia Zannikou ◽  
Fanourios Zannikos
Keyword(s):  
Calibration Curve ◽  
Mass Concentration ◽  
Standard Uncertainty ◽  
Concentration Determination

scholarly journals Development of certified reference materials for physicochemical analysis. Certified reference solutions for the composition of aqueous aluminum, indium, magnesium, nickel and titanium

2019 ◽  
Vol 15 (3) ◽  
pp. 23-32
Author(s):  
I. I. Ermakova ◽  
A. V. Ivanov ◽  
I. N. Zyablikova ◽  
A. N. Shobina
Keyword(s):  
Reference Materials ◽  
Mass Concentration ◽  
Certified Reference Materials ◽  
Storage Conditions ◽  
Physicochemical Analysis ◽  
Standard Uncertainty ◽  
Expanded Uncertainty ◽  
State Register ◽  
Physical Measurements ◽  
Relative Standard

This paper presents information on the development and certification of reference materials (CRM) for the composition of aqueous aluminium, indium, magnesium, nickel, and titanium solutions.CRMs are represented by aqueous solutions containing aluminium, indium, magnesium, nickel, and titanium ions. CRMs have been packed into 5, 10 and 25 cm3 glass ampoules, as well as into 50 and 250 cm3 polypropylene vessels. The certified values of metal mass concentrations were established according to the preparation method.The certified value of the mass concentration of metal ions in the CRMs under study is found to vary within the range of 0.95–1.06 g/dm3. Both the relative expanded uncertainty (under k= 2) of the certified mass concentration and the relative standard uncertainty due to instability do not exceed the values of 0.8 % and 0.069 %, respectively. The developed CRMs are shown to have the shelf life of 3 years provided that standard storage conditions are ensured. The developed CRMs are included into the RF State Register of Certified Reference Materials under the following numbers: CRM 11122–2018, CRM 11123–2018, CRM 11124–2018, CRM 11125–2018, and CRM 11126–2018. The CRMs produced by the All-Russian Research Institute for Optical and Physical Measurements (VNIIOFI) are characterized by the values of expanded uncertainty comparable to those of world leaders in the production of similar materials.

New approaches to radiocarbon calibration arising from statistical developments in IntCal20

2020 ◽  
Author(s):  
Christopher Bronk Ramsey ◽  
Timothy Heaton ◽  
Maarten Blaauw ◽  
Paul Blackwell ◽  
Paula Reimer ◽  
...  
Keyword(s):  
Calibration Curve ◽  
Probability Distribution Function ◽  
Isotope Ratio ◽  
Radiocarbon Dating ◽  
Statistical Approach ◽  
Standard Uncertainty ◽  
Calibration Curves ◽  
Calibration Methods ◽  
Time Periods ◽  
Radiocarbon Calibration

<p>Calibration is a key element of the radiocarbon dating methodology and the underlying Bayesian statistical approach taken, and algorithms used, are well established and used in calibration software and associated analysis packages.  These calibration methods are based on a calibration curve which provides a mean estimate for the radiocarbon isotope ratio (fractionation corrected) expected in samples, and the associated standard uncertainty, both as a function of time (or calendar age).  The measured samples also have their radiocarbon isotope ratio reported in the same form and so the calibration process involves comparison of the sample radiocarbon measurements with the calibration curve at different points on the calendar age scale.  This then yields a probability distribution function, with associated highest probability density ranges, for the sample calendar age.  We discuss here how improvements in the construction of the IntCal20 curve offer new opportunities, enabling users to obtain more from the calibration curve than previously possible and address some of the limitations of previous calibration approaches.</p><p>Previous approaches to calibration assumed that the values of the calibration curves at any time were normally distributed around their estimated mean. However, there are time periods where the distribution of these curves are not well represented by such a normal distribution. This is potentially significant even for calibrations of single samples. The new IntCal20 curve generates multiple possible calibration curves, providing us with the opportunity to identify and adapt to such non-normality.  A second limitation of previous approaches to calibration arises when multiple determinations are used within a broader chronological model. In such cases the usual assumption is that the calibrated uncertainties are independent.  This is certainly not the case if all the samples are the same age (which is currently addressed by combination before calibration) but also is potentially wrong if the samples are close enough in age for there to be correlated uncertainty in the calibration curve.  Again, using the collection of possible curves provided in the construction of IntCal20, rather than just the summary curve, we look at possible solutions to this challenge.  The implications for high-precision chronologies are also discussed.</p>

Preparation and Adding Methods of Nessler's Reagent Having Effects on Determination of Water Quality Ammonia Nitrogen

2013 ◽  
Vol 726-731 ◽  
pp. 1362-1366 ◽  
Author(s):  
He Zhen Wu ◽  
Aie Cao
Keyword(s):  
Water Quality ◽  
Quality Control ◽  
Calibration Curve ◽  
Mass Concentration ◽  
Critical Factor ◽  
Ammonia Nitrogen ◽  
Control Effect ◽  
Recovery Test ◽  
Standard Solution

Nessler's reagent spectrophotometry method is used for determination of water quality ammonia nitrogen. The method is affected by many factors, of which Nessler's reagent is the most critical factor. Preparation and adding methods of Nessler's reagent influence the results of determination , which is based on the determination of absorbance and recovery test. Experimental results show that in the strict control of the speed and the amount of HgCl2 accession, we can get the best effect in the course of preparation of Nessler's reagent. Put a volume of standard solution into a 50mL colorimetric tube, add into Nessler's reagent when diluted with water to about 40mL and then add into water to the reticle (constant volume to 50mL). Determine the absorbance when colors are shown. Draw calibration curve with absorbance as ordinate and mass concentration of ammonia nitrogen as abscissa. The quality control effect of the determination of ammonia nitrogen can be improved by reducing uncertainties.

A Study on Mass Concentration Determination and Property Variations of Produced Polyacrylamide in Polymer Flooding

2011 ◽  
Vol 29 (3) ◽  
pp. 227-235 ◽  
Author(s):  
Y. Qing ◽  
D. Caili ◽  
W. Yefei ◽  
T. Engao ◽  
Y. Guang ◽  
...  
Keyword(s):  
Mass Concentration ◽  
Polymer Flooding ◽  
Concentration Determination

Concentration determination of chromatin in unstained resin-embedded sections by means of Z-contrast in STEM

1990 ◽  
Vol 48 (2) ◽  
pp. 186-187
Author(s):  
M. Haider ◽  
B. Bohrmann
Keyword(s):  
Energy Loss ◽  
Freeze Substitution ◽  
Biological Macromolecules ◽  
Local Concentration ◽  
E Coli ◽  
Concentration Determination ◽  
Phosphorous Content ◽  
Z Contrast ◽  
Electron Energy Loss

The technique of Z-contrast in STEM offers the possibility to determine the local concentration of macromolecules like lipids, proteins or DNA. Contrast formation depends on the atomic composition of the particular structure. In the case of DNA, its phosphorous content discriminates it from other biological macromolecules. In our studies, sections of E. coli, the dinoflagellate Amphidinium carterae and Euglena spec. cells were used which were obtained by cryofixation followed by freeze-substitution into acetone with 3% glutaraldehyde. The samples were then embedded either in Lowicryl HM20 at low temperature or in Epon at high temperature. Sections were coated on both sides with 30Å carbon.The DF- and the inelastic image have been recorded simultaneously with a Cryo-STEM. This Cryo-STEM is equipped with a highly dispersive Electron Energy Loss Spectrometer. With this instrument pure Z-contrast can be achieved either with a Filtered DF-image divided by the inelastic image or, as is used in this paper, by dividing the conventional DF-image by an inelastic image which has been recorded with an inelastic detector whose response is dependent on the total energy loss of the inelastically scattered electrons.

COMPARISON OF VARIOUS METHODS FOR THE CHEMICAL ASSAY OF CORTICOIDS IN URINE

1955 ◽  
Vol 18 (4) ◽  
pp. 374-378
Author(s):  
Mogens Sprechler
Keyword(s):  
Calibration Curve ◽  
Periodic Acid ◽  
Reducing Power ◽  
Standard Technique ◽  
Phosphomolybdic Acid ◽  
Florisil Column ◽  
Chemical Assay ◽  
Chromatographic Procedure ◽  
Acid Reagent

SUMMARY Since 1949 about 10,000 urinary corticoid analyses have been performed routinely in our laboratory. The method used for this purpose was described in 1950 (Sprechler). We determine the corticoids which can be extracted from the urine with chloroform immediately after acidification to pH 1. The extract is washed with sodium hydroxide and water, a Girard separation is performed, and finally the reducing power of the ketonic fraction is measured by means of the phosphomolybdic acid reagent reaction. During the last few years two other chemical reactions have been used for comparison: The formaldehyde and the Porter-Silber method. After a thorough examination of the above methods a standard technique was followed. In the formaldehyde method a microdiffusion in a Conway unit was used instead of distillation of the formaldehyde following the oxidation with periodic acid. The calibration curve was corrected for loss of material by taking the standard doses of DOC through all the procedures of the method. A micromodification of the Porter-Silber method was chosen. Furthermore attempts were made to determine how specific the chromatographic procedure is in the determination of steroids in urinary extracts. For this purpose the Florisil column was used, and the technique described by Nelson & Samuels was followed. Finally we have investigated the glucuronide-bound corticoids in urine in a smaller series of objects.

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