Interlaboratory study on the quantification of calcium phosphate phases by Rietveld refinement

2015 ◽  
Vol 30 (3) ◽  
pp. 231-241 ◽  
Author(s):  
Nicola Döbelin
Keyword(s):  
Standard Deviation ◽  
Calcium Phosphate ◽  
Rietveld Refinement ◽  
Xrd Analysis ◽  
Interlaboratory Study ◽  
Accuracy And Precision ◽  
Crystallite Sizes ◽  
Phase Quantification ◽  
Repeatability Standard Deviation ◽  
Instrument Configuration

An interlaboratory study (ILS, round robin) was conducted to assess the accuracy and precision of the phase quantification of calcium phosphate (CaP) bioceramics by X-ray diffraction (XRD) and Rietveld refinement. For that purpose, a mixture of hydroxyapatite and β-tricalcium phosphate, two CaP phases commonly used in synthetic bone graft substitutes, was prepared and sent to 12 laboratories for XRD analysis. Results from 26 different instruments were received and evaluated statistically according to ASTM E691 – 13. The statistical analysis revealed that the reproducibility standard deviation of phase quantities was approximately two times greater than the repeatability standard deviation, which is obtained by repeating the analysis on a single instrument configuration multiple times. The 95% reproducibility limit for phase quantities was R = ±1.67 wt%. The study also demonstrated that several participants overinterpreted their data in an attempt to refine crystallite sizes of the minor phase.

Protein Nitrogen Unit Precipitation Procedure for Allergenic Extracts: Collaborative Study

1981 ◽  
Vol 64 (6) ◽  
pp. 1435-1438
Author(s):  
Joan C May ◽  
Jenny T C Sih ◽  
◽  
Allergy Laboratories ◽  
J Best ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Coefficient Of Variation ◽  
Collaborative Study ◽  
Precipitation Method ◽  
Protein Nitrogen ◽  
Accuracy And Precision ◽  
Precipitation Procedure ◽  
Allergenic Extracts ◽  
Kjeldahl Method ◽  
Repeatability Standard Deviation

Abstract Protein nitrogen unit (PNU) determination is one of the methods used to test and label the concentration of allergenic extracts. This recently standardized method is applicable to all allergenic extracts. One PNU/mL is equivalent to 1 × 10−5 mg nitrogen determined to be in the material precipitated from 1 m l allergenic extract by phosphotungstic acid (PTA), a protein precipitant. The nitrogen is quantitated by the Kjeldahl method or another analytical method of equivalent accuracy and precision. A collaborative study of the optimized PNU precipitation method in which 6 samples were analyzed in duplicate by 6 laboratories using the Kjeldahl method for the determination of nitrogen yielded a mean of 0.1358 mg N/ml, a repeatability standard deviation and coefficient of variation of 0.0071 mg N/mL and 5.23%, respectively, and a reproducibility standard deviation and coefficient of variation of 0.0188 mg N/mL and 13.84%, respectively. The method has been adopted official first action.

Rapid, accurate phase quantification of multiphase calcium phosphate materials using Rietveld refinement

2006 ◽  
Vol 39 (4) ◽  
pp. 536-543 ◽  
Author(s):  
Joel W. Reid ◽  
Jason A. Hendry
Keyword(s):  
Quality Control ◽  
Calcium Phosphate ◽  
Rietveld Refinement ◽  
Structural Models ◽  
Calcium Hydroxyapatite ◽  
Beta Tricalcium Phosphate ◽  
Scale Factors ◽  
Multiphase Systems ◽  
Phase Quantification ◽  
Zero Offset

Rietveld refinement has been employed to estimate the crystalline phase compositions of multiphase calcium phosphate mixtures containing calcium hydroxyapatite [Ca5(PO4)3OH], and alpha and beta tricalcium phosphate [Ca3(PO4)2]. Two methods were employed using fixed structural models for all three phases and refining the zero offset, scale factors, lattice parameters and one peak breadth parameter using either a constant background (method A) or a background with two refined parameters (method B). Analysis of a matrix of quantitative standards across a broad spectrum of phase compositions indicates that method A results in small systematic deviations of the Rietveld phase compositions (< 1 wt%) from the nominal values, but the systematic deviations are eliminated by refining the background (method B). The methods require approximately 10 min to complete, and are suitable for quality control of calcium phosphate production (and potentially other multiphase systems) when accuracy, precision and time are all significant considerations.

Bioactivity, Wear and Corrosion Resistant Properties of Rare Earth/Calcium Phosphate Composite Coatings

2008 ◽  
Vol 368-372 ◽  
pp. 1194-1197 ◽  
Author(s):  
Chen Ma ◽  
Ying Hui Wang ◽  
Mu Qin Li ◽  
Li Jie Qu
Keyword(s):  
Rare Earth ◽  
Calcium Phosphate ◽  
Composite Coatings ◽  
Xrd Analysis ◽  
Wear Properties ◽  
Corrosion Resistant ◽  
Phosphate Coatings ◽  
Wear And Corrosion ◽  
Micro Arc Oxidation ◽  
Calcium Phosphate Coatings

Rare earth/calcium phosphate composite coatings were fabricated on the surface of Ti-6Al-4V by micro-arc oxidation (MAO) technique. The wear properties and corrosion resistant of rare earth/ calcium phosphate composite coatings in the simulated body fluid (SBF) have been investigated and the bioactivity of the composite coatings were evaluated. The results show that the friction coefficient of the composite coatings in the SBF is only 0.15~0.18 and the anode polarization potential of the coating has been obviously enhanced about 0.18V compared with that of coatings of calcium phosphate coatings. So the composite coatings have excellent wear and corrosion resistant properties. XRD analysis indicates that the composite coatings can induce hydroxyapatite to form on its surface after soaked in SBF for 9d, which shows that the composite coatings own good bioactivity.

scholarly journals Subsolidus solution and ionic conductivity of rock-salt structured Li3+5xTa1−xO4 electroceramics

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
S. Shari ◽  
K.B. Tan ◽  
C.C. Khaw ◽  
Z. Zainal ◽  
O.J. Lee ◽  
...  
Keyword(s):  
Rock Salt ◽  
Xrd Analysis ◽  
Secondary Phases ◽  
Ionic Conductors ◽  
Rock Salt Structure ◽  
Conventional Solid State Reaction ◽  
Salt Structure ◽  
Crystallite Sizes ◽  
Symmetry Space ◽  
Symmetry Space Group

AbstractLithium tantalate solid solution, Li3+5xTa1−xO4 was prepared by conventional solid-state reaction at 925 °C for 48 h. The XRD analysis confirmed that these materials crystallized in a monoclinic symmetry, space group C2/C and Z = 8, which was similar to the reported International Crystal Database (ICDD), No. 98-006-7675. The host structure, β-Li3TaO4 had a rock-salt structure with a cationic order of Li+:Ta5+ = 3:1 over the octahedral sites. A rather narrow subsolidus solution range, i.e. Li3+5xTa1−xO4 (0 ⩽ x ⩽ 0.059) was determined and the formation mechanism was proposed as a replacement of Ta5+ by excessive Li+, i.e. Ta5+ ↔ 5Li+. Both Scherrer and Williamson-Hall (W-H) methods indicated the average crystallite sizes in the range of 31 nm to 51 nm. Two secondary phases, Li4TaO4:5 and LiTaO3 were observed at x = 0.070 and x = −0:013, respectively. These materials were moderate lithium ionic conductors with the highest conductivity of ~2.5 × 10−3 Ω 1 ˙cm−1 at x = 0, at 0 °C and 850 °C; the activation energies were found in the range of 0.63 eV to 0.68 eV.

scholarly journals Sample Sizes Needed for Specified Margins of Relative Error in the Estimates of the Repeatability and Reproducibility Standard Deviations

2005 ◽  
Vol 88 (5) ◽  
pp. 1503-1510 ◽  
Author(s):  
Foster D McClure ◽  
Jung K Lee
Keyword(s):  
Standard Deviation ◽  
Sample Size ◽  
Relative Error ◽  
Analytical Method ◽  
Actual Error ◽  
Repeatability Standard Deviation ◽  
Repeatability And Reproducibility ◽  
Standard Deviations ◽  
True Values ◽  
Addition Formulas

Abstract Sample size formulas are developed to estimate the repeatability and reproducibility standard deviations (sr and sR) such that the actual error in (sr and sR) relative to their respective true values, σr and σR, are at predefined levels. The statistical consequences associated with AOAC INTERNATIONAL required sample size to validate an analytical method are discussed. In addition, formulas to estimate the uncertainties of (sr and sR) were derived and are provided as supporting documentation.Formula for the Number of Replicates Required for a Specified Margin of Relative Error in the Estimate of the Repeatability Standard Deviation

scholarly journals Liquid Chromatographic Determination of Deoxynivalenol in Baby Food and Animal Feed: Interlaboratory Study

2006 ◽  
Vol 89 (4) ◽  
pp. 1012-1020 ◽  
Author(s):  
Joerg Stroka ◽  
Michelle Derbyshire ◽  
Carsten Mischke ◽  
Massimo Ambrosio ◽  
Katy Kroeger ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
High Performance ◽  
Animal Feed ◽  
Chromatographic Determination ◽  
Baby Food ◽  
Interlaboratory Study ◽  
Relative Standard ◽  
Liquid Chromatographic

Abstract An interlaboratory study was conducted for the determination of deoxynivalenol in baby food and animal feed by high-performance liquid chromatography with UV detection. The study included 14 participants representing a cross section of industry, official food control, and research facilities. Mean recoveries reported ranged from 89% (at 120 g/kg) to 85% (at 240 g/kg) for baby food and from 100% (at 200 g/kg) to 93% (at 400 g/kg) for animal feed. On the basis of the results for spiked samples (blind duplicates at 2 levels), as well as those for naturally contaminated samples (blind duplicates at 3 levels), the relative standard deviation for repeatability (RSDr) in analyses of baby food ranged from 6.4 to 14.0% and in analyses of animal feed, from 6.1 to 16.5%. The relative standard deviation for reproducibility (RSDR) in analyses of baby food ranged from 9.4 to 19.5% and in analyses of animal feed, from 10.5 to 25.2%. The HorRat values ranged from 0.4 to 1.0 and from 0.7 to 1.3, for baby food and animal feed, respectively. The method showed acceptable performance for within-laboratory and between-laboratory precision for each matrix, as required by European legislation.

scholarly journals Immunoaffinity Column Cleanup with Liquid Chromatography Using Post-Column Bromination for Determination of Aflatoxins in Hazelnut Paste: Interlaboratory Study

2005 ◽  
Vol 88 (2) ◽  
pp. 526-535 ◽  
Author(s):  
Hamide Z Senyuva ◽  
John Gilbert
Keyword(s):  
Liquid Chromatography ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Aflatoxin B1 ◽  
The United States ◽  
Interlaboratory Study ◽  
Immunoaffinity Column ◽  
Test Portion ◽  
Relative Standard

Abstract An interlaboratory study was conducted to evaluate the effectiveness of an immunoaffinity column cleanup liquid chromatography (LC) method for determination of aflatoxin B1 and total aflatoxins in hazelnut paste at European regulatory limits. The test portion was extracted with methanol–water (6 + 4). The extract was filtered, diluted with phosphate-buffered saline (PBS) solution to a specified solvent concentration, and applied to an immunoaffinity column containing antibodies specific to aflatoxins. The aflatoxins were removed from the immunoaffinity column with methanol, and then quantified by reversed-phase LC with post-column derivatization (PCD) involving bromination. The PCD was achieved with electrochemically generated bromine (Kobra Cell®) followed by fluorescence detection (except for one participant who used pyridinum hydrobromide perbromide for bromination). Hazelnut paste, both naturally contaminated with aflatoxins and blank (&lt;0.1 ng/g) for spiking by participants with aflatoxins, was sent to 14 collaborators in Belgium, The Netherlands, Spain, Turkey, the United Kingdom, and the United States. Test portions were spiked at levels of 4.0 and 10.0 ng/g for total aflatoxins by participants using supplied total aflatoxins standards. Recoveries for total aflatoxins and aflatoxin B1 averaged from 86 to 89%. Based on results for naturally contaminated samples (blind duplicates at 3 levels ranging from 4.0 to 11.8 ng/g total aflatoxins), the relative standard deviation for repeatability (RSDr) ranged from 2.3 to 3.4% for total aflatoxins and from 2.2 to 3.2% for aflatoxin B1. The relative standard deviation for reproducibility (RSDR) ranged from 6.1 to 7.0% for total aflatoxins and from 7.3 to 7.8% for aflatoxin B1. The method showed exceptionally good within-laboratory and between-laboratory precision for hazelnut paste, as evidenced by HORRAT values, which in all cases were significantly below target levels, the low levels of determination for both aflatoxin B1 and total aflatoxins.

Colorimetric Method for Carbadox in Feeds: Collaborative Study

1977 ◽  
Vol 60 (5) ◽  
pp. 1059-1063
Author(s):  
John T Goras
Keyword(s):  
Standard Deviation ◽  
Stannous Chloride ◽  
Collaborative Study ◽  
Colorimetric Method ◽  
Feed Supplement ◽  
Colored Complex ◽  
Feed Supplements ◽  
Repeatability Standard Deviation ◽  
Standard Additions ◽  
The Mean

Abstract A colorimetric method for determining carbadox in complete swine feeds and feed supplements was collaboratively studied. Carbadox is separated from feed with CHCl3-methanol (3+1) and then separated from interfering materials by a series of solvent-solvent extractions. The drug is isolated as a dry residue, reconstituted, and reacted with stannous chloride to form a colored complex that is measured at 520 nm. The method of standard additions is used to compensate for a feed or feed supplement matrix effect. Twenty-seven laboratories assayed feeds containing 0.0013, 0.0053, and 0.0242% carbadox. The repeatability standard deviation (σ0) and reproducibility standard deviation (σx) were σ0 = 0.00014%, σx = 0.00035% (29% of grand mean) for 0.0013% carbadox in feed; σ0 = 0.00025%, σx = 0.00037% (6.7% of grand mean) for 0.0053% carbadox in feed; and σ0 = 0.0019%, σx = 0.0024% (9.6% of grand mean) for 0.0242% carbadox in feed. The between-laboratory variance ratio was not significant for feeds containing 0.0013 and 0.0053% carbadox, but was significant for feeds containing 0.0242% carbadox. The mean recovery values for feeds containing 0.0013, 0.0053, and 0.0242% carbadox were 92, 104, and 103%, respectively. The method was adopted as official first action for feeds having a guaranteed potency of 0.0055% carbadox or higher.

scholarly journals Application of parametric speakers to radio acoustic sounding system

2019 ◽  
Vol 12 (10) ◽  
pp. 5699-5715 ◽  
Author(s):  
Ahoro Adachi ◽  
Hiroyuki Hashiguchi
Keyword(s):  
Standard Deviation ◽  
Temperature Difference ◽  
Acoustic Waves ◽  
Urban Areas ◽  
Vertical Profile ◽  
Wind Profiler ◽  
Acoustic Beam ◽  
Acoustic Sounding ◽  
Accuracy And Precision ◽  
Virtual Temperature

Abstract. In this study, a wind profiler with a radio acoustic sounding system (RASS) and operational radiosonde measurements were used to investigate the technical practicability and reliability of using parametric speakers to measure the vertical profile of virtual temperature. Characteristics of parametric speakers include high directivity and very low side lobes, which are preferable for RASS, especially those operating in urban areas. The experiments were conducted on fine days with light winds to mitigate the effects of the horizontal and vertical components of wind on acoustic waves used for RASS. The results of this study indicated that, although parametric speaker RASS is susceptible to horizontal winds due to the narrower acoustic beam, bias and standard deviation of parametric speaker RASS versus radiosonde virtual temperature difference (0.1 ∘C, 0.4 ∘C) were close to those from acoustic speakers (0.0 ∘C, 0.4 ∘C). In addition, when compared with acoustic speaker RASS, the values for the parametric speaker RASS were even smaller (0.1 ∘C, 0.2 ∘C). Based on these results, it is concluded that the parametric speaker RASS has accuracy and precision comparable with acoustic speaker RASS despite its high directivity of sound.

An Adaptive Statistically Based Controller for Through-Feed Centerless Grinding

2000 ◽  
Vol 123 (3) ◽  
pp. 380-386 ◽  
Author(s):  
Richard W. Cowan ◽  
Daniel J. Schertz ◽  
Thomas R. Kurfess
Keyword(s):  
Standard Deviation ◽  
Statistical Approach ◽  
High Volume ◽  
Manufacturing Processes ◽  
Control Methods ◽  
Statistical Control ◽  
Accuracy And Precision ◽  
Self Tuning ◽  
Centerless Grinding ◽  
The Mean

The purpose of this research is to develop a statistically based controller that is “self-tuning.” High volume manufacturing processes such as through-feed centerless grinding are best controlled with a statistical approach, but traditional methods of statistical control generally rely on fixed parameters that must be determined. These values must be precisely known and the true physical characteristics they model must remain constant throughout grinding, or traditional statistical control methods may break down. The mean and standard deviation of a process are measures of its accuracy and precision. The scheme developed here makes control decisions based on the real-time values of these quantities. This self-adjusting ability can compensate for changes in machine parameters as they occur.

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