scholarly journals Determination of a Two-Tailed 100(1-α)% Upper Limit on the Relative Error in the Laboratory-to-Laboratory Standard Deviation Obtained from an Interlaboratory Study

2009 ◽  
Vol 92 (5) ◽  
pp. 1593-1601 ◽  
Author(s):  
Foster D McClure ◽  
Jung K Lee
Keyword(s):  
Monte Carlo ◽  
Standard Deviation ◽  
Relative Error ◽  
Analytical Method ◽  
Interlaboratory Study ◽  
Chi Square ◽  
True Value ◽  
Upper Limit ◽  
Interlaboratory Studies

Abstract For some classes of analytical methods, it is assumed that the error in the laboratory-to-laboratory standard deviation (sL) is appreciable. To demonstrate the magnitude of this error in sL for such methods, formulas were derived to obtain a two-tailed 100(1-α)% upper limit on the relative error in sL obtained from an interlaboratory study, assuming that the laboratory-to-laboratory variance (sL2) obtained in the validation of an analytical method is approximately normal and/or Chi-square distributed. This 100(1-α)% upper limit is referred to as a margin of relative error in sL (MRE(sL)). Monte Carlo simulations were performed, and the results compared satisfactorily with the formula calculations. To aid in designing future interlaboratory studies in which concern is focused on the magnitude of the uncertainty in sL, expressed as a proportion of the true value (σL), a formula was derived to determine the number of laboratories needed to attain a given MRE in sL for a stated number of replicates per laboratory.

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 (<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.

Experimental Designs for Interlaboratory Precision Experiments: Comparison of ISO 5725 with Draft NEN 6303

1989 ◽  
Vol 72 (1) ◽  
pp. 34-37 ◽  
Author(s):  
J Zaalberg
Keyword(s):  
Standard Deviation ◽  
Edible Oils ◽  
Collaborative Study ◽  
Experimental Designs ◽  
Interlaboratory Experiments ◽  
Interlaboratory Studies ◽  
Repeatability Standard Deviation ◽  
Level Design ◽  
Iso 5725

Abstract To determine the precision of standardized analytical methods, interlaboratory experiments are carried out in which several laboratories analyze identical samples from well homogenized batches of material. From the test results, estimates of the standard deviations under repeatability as well as under reproducibility conditions are calculated. In the present work, the experimental designs recommended in the International Standard ISO 5725 have been compared with a design proposed in the draft Netherlands Standard NEN 6303. This has been done by comparing their mathematical models as well as by applying them to the results of a recent collaborative study on the determination of heavy metals in edible oils and fats. The reproducibility standard deviation is estimated equally well with both Standards, but it appeared that the designs given in ISO 5725 can lead to serious underestimation (uniform-level design) or overestimation (split-level design) of the repeatability standard deviation. By using the design proposed in NEN 6303, these biases can be avoided. Hence, it is recommended that interlaboratory studies be organized according to the design of NEN 6303.

scholarly journals A PRIVATE MODEL OF INDEX IS A HINDRANCE OF STABILITY OF THE STATION OF ACCOMPANIMENT OF AIM OF ZENITHAL ROCKET COMPLEX OF SHORTER-RANGE

2020 ◽  
pp. 56-66
Author(s):  
V. Kudryashov ◽  
A. Artemenko ◽  
O. Kolomiitsev ◽  
R. Oliynik ◽  
Y. Zhivetc ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Analytical Method ◽  
High Efficiency ◽  
Modern Approach ◽  
Partial Model ◽  
Informative Parameters ◽  
Location Channel ◽  
Radio Location ◽  
Mathematical Design

Protecting from the action of radio of hindrances on the elements of zenithal rocket complex of shorter-range is one of important problems, that requires modern approach for her decision. Presently, influence of active hindrances is certain yet not enough on possibilities of armament on the defeat of air aims. In the article the analysis of influence of hindrances of different closeness is conducted on the station of accompaniment of aims of fighting machine of zenithal rocket complex shorter-range. The partial model of determination of index is offered hindrance of stability of the station of accompaniment of aim of zenithal rocket complex of shorter-range. The brought partial model over allows an analytical method to conduct the evaluation of values of conditional hit of model aim probabilities under various conditions. Mathematical calculations are conducted for: amplification of aerial of accompaniment of aim of fighting machine and aerials factors hindrance of producer; powers of hindrances on the entrance of accompaniment of aim of fighting machine; to the maximum sensitiveness of accompaniment of aim of fighting machine and relations hindrance/noise in the radio-location channel of accompaniment of aim; standard deviation of error of aiming of rocket depending on distance to the point of meeting of rocket with an aim in the zone of defeat taking into account influence of hindrances on the radio-location channel of accompaniment of aim of fighting machine; probabilities of passing of rocket in the «tube» of the set radius and conditional hit of aim probability at firing by one rocket; coefficient of зпомеха stability of accompaniment of aim of fighting machine; to conditional hit of aim probability hindrance of producer at firing by two rockets. On the accepted entry informative parameters and technical descriptions of accompaniment of aim of fighting machine certainly her maximum sensitiveness and relation hindrance/noise in this radio-location channel. On results mathematical calculations (mathematical design) corresponding charts that over is brought are got. From charts it is possible to define high efficiency of firing rockets on a model (air) aim.

scholarly journals Immunoaffinity Column Cleanup with Liquid Chromatography for Determination of Aflatoxin B1 in Corn Samples: Interlaboratory Study

2007 ◽  
Vol 90 (3) ◽  
pp. 765-772 ◽  
Author(s):  
Carlo Brera ◽  
Francesca Debegnach ◽  
Valentina Minardi ◽  
Elena Pannunzi ◽  
Barbara De Santis ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Aflatoxin B1 ◽  
Interlaboratory Study ◽  
Precolumn Derivatization ◽  
Immunoaffinity Column ◽  
Relative Standard ◽  
Postcolumn Derivatization

Abstract An interlaboratory study was conducted to evaluate the effectiveness of an immunoaffinity column cleanup liquid chromatography (LC) method for the determination of aflatoxin B1 levels in corn samples, enforced by European Union legislation. A test portion was extracted with methanolwater (80 + 20); the extract was filtered, diluted with phosphate-buffered saline solution, filtered on a microfiber glass filter, and applied to an immunoaffinity column. The column was washed with deionized water to remove interfering compounds, and the purified aflatoxin B1 was eluted with methanol. Aflatoxin B1 was separated and determined by reversed-phase LC with fluorescence detection after either pre- or postcolumn derivatization. Precolumn derivatization was achieved by generating the trifluoroacetic acid derivative, used by 8 laboratories. The postcolumn derivatization was achieved either with pyridinium hydrobromide perbromide, used by 16 laboratories, or with an electrochemical cell by the addition of bromide to the mobile phase, used by 5 laboratories. The derivatization techniques used were not significantly different when compared by the Student's t-test; the method was statistically evaluated for all the laboratories. Five corn sample materials, both spiked and naturally contaminated, were sent to 29 laboratories (22 Italian and 7 European). Test portions were spiked with aflatoxin B1 at levels of 2.00 and 5.00 ng/g. The mean values for recovery were 82% for the low level and 84% for the high contamination level. Based on results for spiked samples (blind pairs at 2 levels) as well as naturally contaminated samples (blind pairs at 3 levels), the values for relative standard deviation for repeatability (RSDr) ranged from 9.9 to 28.7%. The values for relative standard deviation for reproducibility (RSDR) ranged from 18.6 to 36.8%. The method demonstrated acceptable within- and between-laboratory precision for this matrix, as evidenced by the HorRat values.

Colorimetric Determination of Arprinocid in Feed

1978 ◽  
Vol 61 (5) ◽  
pp. 1078-1082
Author(s):  
David W Fink ◽  
Kobert P Martin ◽  
James V Pivnichny ◽  
Jung-Sook K Shim
Keyword(s):  
Standard Deviation ◽  
Reaction Time ◽  
Analytical Method ◽  
Acidic Solution ◽  
Feed Additives ◽  
Colorimetric Determination ◽  
Colorimetric Measurement ◽  
Relative Standard ◽  
Zinc Reduction

Abstract An analytical method has been developed for the determination of arprinocid (9-(2-chloro- fluorophenylmethyl) -9ff-purin-6-amine) in feed, based upon measurement of the absorbance of the diazo chromophore formed from product of zinc reduction of the drug in acidic solution. The analyte is extracted from the feed into chloroform in the presence of a pH 7 phosphate buffer and isolated by adsorption chromatography on alumina, followed by partitioning between hexane and 0.15M HC1. The reduction product in the aqueous phase is then treated for colorimetric measurement. This procedure has been applied to determining 0.0010-0.0080% arprinocid in feed with precision of <5% relative standard deviation near the middle of this concentration range. Of 32 feed additives examined, only zoalene and sulfamethazine were serious interferences. study and discussion of several factors, e.g., reaction time, pH, and amount of zinc metal, that affect the analytical reactions are also included.

Collaborative Study of the Determination of Ethoxyquin in Feeds

1963 ◽  
Vol 46 (2) ◽  
pp. 306-309
Author(s):  
Richard S Gordon
Keyword(s):  
Standard Deviation ◽  
Entire Range ◽  
Task Force ◽  
Collaborative Study ◽  
Mixed Feed ◽  
Absolute Value ◽  
Background Values ◽  
True Value ◽  
The Mean

Abstract The previously reported method for the determination of Santoquin (ethoxyquin) in feeds yielded highly reproducible results; duplicate determinations varied ± 2.6% from the mean. The use of different fluorometers gave a greater range of background values than previously. However, the average values obtained from all laboratories using the method was 99.9% of the true value over the entire range of Santoquin concentrations (0—200 ppm) studied, and 97.2% of the absolute value in the range of Santoquin concentration (100—150 ppm) ordinarily encountered in mixed feed. The standard deviation from all laboratories in the 100—150 ppm range is about 7.4% of the value observed. It is recommended that the method as previously reported be adopted as official, first action and the task force expanded to include more laboratories with a still greater variety of fluorometers before recommending that the method be adopted as official, final action.

scholarly journals SIMULTANEOUS DETERMINATION OF PARACETAMOL AND IBUPROFENE MIXTURES BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

2010 ◽  
Vol 3 (1) ◽  
pp. 9-13 ◽  
Author(s):  
Sophi Damayanti ◽  
Slamet Ibrahim ◽  
Kurnia Firman ◽  
Daryono H Tjahjono
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Standard Deviation ◽  
Retention Time ◽  
Analytical Method ◽  
Phosphate Buffer ◽  
Mobile Phase ◽  
High Performance ◽  
Relative Standard

Analytical method for the determination of paracetamol and ibuprofene mixtures has been developed by High Performance Liquid Chromatography using C-18 column and acetinitrile - phosphate buffer pH = 4.5 (75:25) containing 0.075% sodium hexanesulfunate as a mobile phase. The detector was set at 215 nm. Using such conditions, retention time for paracetamol and ibuprofen was 4.89 and 7.11 min, respectively. The recovery for paracetamol and ibuprofen was found to be 101.07± 0.73% and 102.02 ± 1.58%, respectively. The detector limits of the method was 1.30 and 1.60 μg/mL with the relative standard deviation (RSD) 0.74 and 1.52% for paracetamol and ibuprofen, respectively.   Keywords: paracetamol, ibuprofen, multi-component, validation, HPLC.

scholarly journals Voltammetric sensor based on the copper (II) amino acid complex for the determination of tryptophan enantiomers

2021 ◽  
Vol 25 (3) ◽  
pp. 193-204
Author(s):  
R. A. Zilberg ◽  
◽  
Yu. B. Teres ◽  
L. R. Zagitova ◽  
Yu. A. Yarkaeva ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Relative Error ◽  
Biological Fluids ◽  
Biologically Active ◽  
Voltammetric Sensor ◽  
Potential Sweep ◽  
Tryptophan Enantiomers ◽  
Relative Standard

A voltammetric sensor based on a composite of polyarylene phthalide and graphitized carbon black Carboblack C modified with chelate complexes of L-argenato-L-alaninate of copper (II) has been developed for the recognition and selective determination of tryptophan enantiomers. The conditions for modifying the sensor are optimized, the effective surface area (A = 4.38 ± 0.06 mm2) and the effective resistance (Ret = 1.29 ± 0.08 kΩ) are calculated. The optimal conditions for recording voltammograms of tryptophan enantiomers are selected: the range of operating potentials is 0.5-1.2 V, the potential sweep rate is 20 mV/s, the holding time of the electrode in the test solution is 5 s. The electrochemical and analytical characteristics of the sensor were studied when registering differential pulse voltammograms of tryptophan enantiomers. It is shown that the dependence of the analytical signal on the concentration is linear in the range from 1.25·10-6 to 1·10-3 M with detection limits of 0.90·10-6 M for L-Trp and 0.66·10-6 M for D-Trp. The developed sensor shows the greatest sensitivity to D-Trp. The sensor has been successfully tested to determine the content of L- and D-Trp in enantiomer solutions in the presence of excipients that are part of medicines and biologically active additives. The proposed sensor allows the determination of tryptophan enantiomers in human urine and blood plasma. To evaluate the analytical capabilities of the sensor, the "entered-found" method was used. When determining tryptophan enantiomers in model solutions, the relative standard deviation does not exceed 2.3 %, and the relative error is 1.7 %. When determining D- and L-Trp in biological fluids, the relative standard deviation ranges from 0.3-1.7 %, and the relative error ranges from 0.3-5.6 %. The research results show that there is no significant systematic error.

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