Static TOF-SIMS — a VAMAS interlaboratory study. Part I. Repeatability and reproducibility of spectra

2005 ◽  
Vol 37 (8) ◽  
pp. 651-672 ◽  
Author(s):  
I. S. Gilmore ◽  
M. P. Seah ◽  
F. M. Green
Keyword(s):  
Interlaboratory Study ◽  
Tof Sims ◽  
Repeatability And Reproducibility

scholarly journals Youden Analysis of Karl Fischer Titration Data from an Interlaboratory Study Determining Water in Animal Feed, Grain, and Forage

2005 ◽  
Vol 88 (6) ◽  
pp. 1840-1841 ◽  
Author(s):  
Frank E Jones
Keyword(s):  
Animal Feed ◽  
Systematic Errors ◽  
Interlaboratory Study ◽  
Matched Pairs ◽  
Karl Fischer Titration ◽  
Karl Fischer ◽  
Collaborative Studies ◽  
Titration Data ◽  
Repeatability And Reproducibility

Abstract Data from a recent interlaboratory study of the determination of water (moisture) in animal feed, grain, and forage (plant tissue) by Karl Fischer titration were re-analyzed using Youden plots. The purpose was to show the unique ability these plots possess of separating random and systematic errors visually while providing numerical estimates of the precision and the systematic error of the method. Furthermore, the usefulness of the technique is underscored because AOAC INTERNATIONAL allows the use of matched pairs in collaborative studies to obtain estimates of repeatability and reproducibility.

Gas-Liquid Chromatographic Determination of Mirex and Photomirex in the Presence of Poly chlorinated Biphenyls: Interlaboratory Study

1980 ◽  
Vol 63 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Ross J Norstrom ◽  
Henry T Won ◽  
Micheline Van Hove Holdrinet ◽  
Patrick G Calway ◽  
Caroline D Naftel
Keyword(s):  
Chromatographic Determination ◽  
Interlaboratory Study ◽  
Gas Liquid Chromatography ◽  
Coefficients Of Variation ◽  
Fuming Nitric Acid ◽  
Liquid Chromatographic Determination ◽  
Repeatability And Reproducibility ◽  
Concentrated Sulfuric Acid ◽  
Liquid Chromatographic

Abstract Mirex and photomirex (8-monohydromirex) were separated from polychlorinated biphenyls (PCBs) and other aromatic compounds by nitration with fuming nitric acid-concentrated sulfuric acid and removal of nitro-PCBs on an alumina microcolumn; the compounds were then determined by gas-liquid chromatography. Recoveries of Mirex and photomirex were 102±8 and 104±5%, respectively, from standard solutions which had a PCB-to-Mirex and photomirex ratio of 1000. Recoveries from fortified, uncontaminated samples of sediment, fish, and eggs averaged 93±7 and 92±3% for Mirex and photomirex, respectively. The coefficients of variation for repeatability and reproducibility averaged 8 and 15%, respectively, in an interlaboratory study conducted by 4 laboratories using extracts of naturally contaminated substrates (sediment, carp, eel, and gull egg). Levels of Mirex in the samples ranged from 0.1 to 8 mg/kg, and levels of PCB ranged from 0.5 to 166 mg/kg.

scholarly journals Evaluation of Modified PCR Quantitation of Genetically Modified Maize and Soybean Using Reference Molecules: Interlaboratory Study

2009 ◽  
Vol 92 (1) ◽  
pp. 223-233 ◽  
Author(s):  
Takashi Kodama ◽  
Hideo Kuribara ◽  
Yasutaka Minegishi ◽  
Satoshi Futo ◽  
Masatoshi Watai ◽  
...  
Keyword(s):  
Quantitative Methods ◽  
Conversion Factor ◽  
Recombinant Dna ◽  
Genetically Modified ◽  
Interlaboratory Study ◽  
Chain Reaction ◽  
Specific Sequence ◽  
Reference Plasmid ◽  
Repeatability And Reproducibility ◽  
Polymerase Chain

Abstract Real-time polymerase chain reaction (PCR)-based quantitative methods were previously developed and validated for genetically modified (GM) maize or soy. In this study, the quantification step of the validated methods was modified, and an interlaboratory study was conducted. The modification included the introduction of the PCR system SSIIb 3 instead of SSIIb 1 for the detection of the taxon-specific sequence of maize, as well as the adoption of colE1 as a carrier included in a reference plasmid solution as a replacement for salmon testis. The interlaboratory study was conducted with the ABI PRISM<sup/> 7700 and consisted of 2 separate stages: (1) the measurement of conversion factor (Cf) value, which is the ratio of recombinant DNA (r-DNA) sequence to taxon-specific sequence in each genuine GM seed, and (2) the quantification of blind samples. Additionally, Cf values of other instruments, such as the ABI PRISM 7900 and the ABI PRISM 7000, were measured in a multilaboratory trial. After outlier laboratories were eliminated, the repeatability and reproducibility for 5.0 samples were <15.8 and 20.6, respectively. The quantitation limits of these methods were 0.5 for Bt11, T25, and MON810, and 0.1 for GA21, Event176, and RR soy. The quantitation limits, trueness, and precision of the current modified methods were equivalent to those of the previous methods. Therefore, it was concluded that the modified methods would be a suitable replacement for the validated methods.

Determination of Nitrogen Content in Milk by the Kjeldahl Method Using Copper Sulfate: Interlaboratory Study

1988 ◽  
Vol 71 (5) ◽  
pp. 893-898 ◽  
Author(s):  
R Grappin ◽  
William Horwitz
Keyword(s):  
Quality Control ◽  
Nitrogen Content ◽  
Copper Sulfate ◽  
Interlaboratory Study ◽  
Internal Quality ◽  
Relative Standard ◽  
Nitrogen Concentrations ◽  
Kjeldahl Method ◽  
Repeatability And Reproducibility

Abstract Copper sulfate was substituted for mercury as the catalyst in the International Dairy Federation (IDF) Standard 20A:1986 method for the determination of nitrogen content in milk. The substitution was supported by results obtained in an interlaboratory study by 24 laboratories in 12 countries. Each laboratory analyzed 12 test samples of milk as blind duplicates in a double split level design with high, medium, and low nitrogen concentrations. The method protocol requires the concurrent analyses of an ammonium salt solution and a tryptophan solution as internal quality control standards with a minimum nitrogen recovery between 99 and 100% for the former and at least 98% for the latter. The repeatability and reproducibility relative standard deviations are 0.5 and 1%, respectively, for the range 0.35-0.70 g N/100 g. The performance of the laboratories that did not meet the required quality control specifications was clearly poorer than that of those that did meet the specifications.

scholarly journals Analysis of DDT Residues in Soil by ELISA: An International Interlaboratory Study

2001 ◽  
Vol 84 (1) ◽  
pp. 134-142 ◽  
Author(s):  
Britt M Maestroni ◽  
John H Skerritt ◽  
Ian G Ferris ◽  
Arpad Ambrus ◽  
R Amin ◽  
...  
Keyword(s):  
Organic Matter Content ◽  
Developed Countries ◽  
Matter Content ◽  
Interlaboratory Study ◽  
Particle Size Distributions ◽  
Relative Standard ◽  
Repeatability And Reproducibility ◽  
Performance Statistics ◽  
Different Levels ◽  
Developing And Developed Countries

Abstract An international interlaboratory study was conducted to determine the performance of a group of laboratories from developing and developed countries. The study used a commercial microwell ELISA on unknown samples spiked with different levels of DDT. The study design was based on Youden pairs and balanced replicates. Two soils, differing in particle size distributions, organic matter content, and cation-exchange capacities and thought to be DDT-free, were spiked at 5 DDT levels between 0.025 and 2 mg/kg. Nineteen laboratories in 17 countries took part in the collaborative trial; of these, the majority were modestly equipped laboratories in developing countries. Samples were analyzed without filtration or cleanup and using standards of pure DDT in methanol. Data were analyzed for repeatability and reproducibility, and average recoveries at the spike levels were calculated. Mean real recoveries for both soils were similar (103% for soil A and 100% for soil B), with values between 0.1 and 2 mg/kg DDT. Precision estimates were best in the linear working range of the assay (0.1–0.5 mg/kg DDT), with reproducibility relative standard deviations (RSDR) typically averaging about 38 and 46% near the upper and lower detection limits, respectively. Corresponding repeatability relative standard deviation (RSDr) values were 20–36% and 36–57%. Thus, even though much of the trial was performed under developing country conditions, performance statistics were similar to other reported results obtained with ELISAs on small molecules of agricultural importance, such as mycotoxins and pesticide and antibiotic residues.

Applications of Time-OF-Flight Secondary Ion Mass Spectrometry (TOF-SIMS)

1990 ◽  
Vol 48 (2) ◽  
pp. 308-309
Author(s):  
Bruno Schueler ◽  
Robert W. Odom
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Structural Information ◽  
Time Of Flight ◽  
Biological Tissues ◽  
Polymer Surfaces ◽  
Tof Sims ◽  
Secondary Ions ◽  
Ion Mass Spectrometry ◽  
Secondary Ion

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) provides unique capabilities for elemental and molecular compositional analysis of a wide variety of surfaces. This relatively new technique is finding increasing applications in analyses concerned with determining the chemical composition of various polymer surfaces, identifying the composition of organic and inorganic residues on surfaces and the localization of molecular or structurally significant secondary ions signals from biological tissues. TOF-SIMS analyses are typically performed under low primary ion dose (static SIMS) conditions and hence the secondary ions formed often contain significant structural information.This paper will present an overview of current TOF-SIMS instrumentation with particular emphasis on the stigmatic imaging ion microscope developed in the authors’ laboratory. This discussion will be followed by a presentation of several useful applications of the technique for the characterization of polymer surfaces and biological tissues specimens. Particular attention in these applications will focus on how the analytical problem impacts the performance requirements of the mass spectrometer and vice-versa.

Analysis of factors affecting the repeatability and reproducibility of elastographic measurements of thyroid nodules

2014 ◽  
Author(s):  
Kamil Brzozowski ◽  
Martyna Wojtaszek-Nowicka ◽  
Joanna Lukowska ◽  
Mariusz Klencki ◽  
Dorota Slowinska-Klencka
Keyword(s):  
Thyroid Nodules ◽  
Factors Affecting ◽  
Repeatability And Reproducibility

Interlaboratory Study of Standard Methods for Testing Multiwire Steel Prestressing Strand

PCI Journal ◽  
2020 ◽  
Vol 65 (4) ◽  
Author(s):  
Rémy D. Lequesne ◽  
William N. Collins ◽  
Enrico Lucon ◽  
David Darwin ◽  
Ashwin Poudel
Keyword(s):  
Interlaboratory Study ◽  
Standard Methods ◽  
Prestressing Strand
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