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Gamma Spectrometry
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
The sum of the considered uncertainties in the right-hand side of Eq. 8.12 is then u2(Ax,corr) = 6.67·10-5 + 0.000234 + 0 + 0.01532(=0.000234) + 0 + 0.0172(=0.000289) = 0.000758. The relative standard deviation s(Ax,corr) is thus the square root of this number, that is, 0.028. This means that the total relative uncertainty, expressed in one standard deviation, is 2.8 per cent. Expressed with on 99 per cent confidence level, the relative uncertain becomes 1.96·0.028=5.4 per cent. To communicate this result, the activity concentration value should thus be reported as being Ax,corr(±1.96·σ)=4799.6±259 Bq kg-1.
Infrared Spectroscopy
Published in Adorjan Aszalos, Modern Analysis of Antibiotics, 2020
Zollner [55] reports the determination of penicillin and phenoxymethyl-penicillin in tablets by measuring the β-lactam-associated absorbances at 1776 and 1788 cm-1. Measurements were made on a chloroform solution of the materials. A relative standard deviation of 2% is reported.
Principles and Problems of Cadmium Analysis
Published in Lars Friberg, Tord Kjellström, Carl-Gustaf Elinder, Gunnar F. Nordberg, Cadmium and Health: A Toxicological and Epidemiological Appraisal, 2019
Carl-Gustaf Elinder, Birger Lind
Precision denotes the random error of the method. If replicate analysis provides data which are closely clustered, the method is said to have a high precision. A high precision makes it possible to measure small changes in concentrations with confidence but does not imply per se that the results are accurate. If the variation in individual measurements can be assumed to follow a Gaussian distribution, the best description of precision is the standard deviation (Sx) from the mean () of a number of analyses of the same sample. Often precision is given as relative standard deviation, or coefficient of variation = Sx/55.
Nitrous anhydrase activity of carbonic anhydrase II: cysteine is required for nitric oxide (NO) dependent phosphorylation of VASP in human platelets
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2021
Dimitrios Tsikas, Stepan Gambaryan
The previously reported GC-MS method for nitrite and nitrate had been originally validated for 100-µL sample aliquots15,16. This method was adapted to 10-µL aliquots and validated for the CA microassay which involves the use of H218O needed to prepare the aqueous buffer3. For highest derivatization yield of nitrite, the incubation time was 5 min. Under these conditions, nitrate cannot be quantified accurately15. We compared in parallel the methods using 100-µL (in quadruplicate) and 10-µL aliquots (in duplicate) of nitrite solutions in 100 mM Tris-HCl buffer, pH 7.4, in H216O at added nitrite concentrations of 0, 2.5, and 5.0 µM. These concentrations were chosen because they were expected to be formed in experiments in H218O-Tris buffer. The relative standard deviation values were 2.9% and 2.4%, 0.5% and 1.0%, and 3.1% and 4.3%, respectively. The regression equations obtained from linear regression analyses of measured nitrite (y) versus added nitrite (x) were y = 0.752 + 0.645x, r2=0.9945 for the 100-µL samples and y = 0.800 + 0.668x, r2=0.9998 for the 10-µL. The y-axis intercepts reveal nitrite concentrations in the Tris-HCl buffer of 0.75 µM and 0.80 µM, respectively. The slope values of the regression equations of 0.645 and 0.668 are very close indicating almost complete agreement (96.5%) between the procedures in the investigated concentration range.
A scanning and image processing system with integrated design for automated micronucleus scoring
Published in International Journal of Radiation Biology, 2020
Tímea Hülber, Zsuzsa S. Kocsis, Enikő Kis, Géza Sáfrány, Csilla Pesznyák
The MN yield corresponding to 2 Gy dose is in the range of 300 MN per 1000 BN cells. The theoretical relative standard deviation of this value is 7%. The range of the uncertainty examined in the context of other contributors should be compared to this 7% since this is the theoretical minimum of the error of dose estimation. All the other contributors can be reduced with the finetuning of the sample preparation and scoring process, except the individual variability (see the last column of Table 6). The four contributors were analyzed in regard to the three scoring types (manual, semi-automatic and full-automatic). Some of the error factors affect all the three scoring methods in the same way, but for example, the difference between the results of involving multiple human scorers is only an issue in manual and semi-automatic cases. It is a fair assumption that the factors are independent from each other, so their combined variance can be calculated as the sum of the variances of the individual factors. When all of the errors are summed up for the different scoring methods, the final values do not significantly differ. The exact values of the discussed uncertainties can differ for doses higher or lower than the examined 2 Gy, but their range relative to each other remains the same.
In vitro toxicity assessment of rivaroxaban degradation products and kinetic evaluation to decay process
Published in Drug and Chemical Toxicology, 2019
Nathalie R. Wingert, Marcelo D. Arbo, Gabriela Göethel, Bárbara da Costa, Louise F. Altknecht, Solange C. Garcia, Martin Steppe
DPs were detected when RIV solution was diluted with acid and alkali media, and exposed to UVC radiation. RIV initial concentration was not changed and no degradant was detected when the sample was exposed to high temperature only, according to the experimental conditions. Method specificity was evaluated by software peak purity tool. Results showed peak purity index higher than 0.999 for all conditions tested, demonstrating the absence of co-eluting substances along with RIV peak. No interferences were also detected when the analysis of placebo mixture was preceded. Method linearity was assessed in six levels (1.0; 5.0; 10; 20; 40; and 60.0 µg/mL). ANOVA demonstrated that obtained values correspond to a linear regression (Fcalc 2470787 > Ftab 2.61, α = 0.05) with no deviation from linearity (Fcalc 2.41 < Fcritical 2.84, α = 0.05). Relative standard deviation (RSD) and relative error were significantly small, as expected for a reliable analytical method. All results related to HPLC method validation (Table 2) were within the acceptable conditions and values.