AOAC ERP Gluten Assays - Dec 2018
15. Check the shape of the standard curve (not the precise OD‐values) if it is similar to the Quality Assurance Certificate enclosed in the test kit. 16. Repeat the procedure (from 1 to 15) using the remaining 21 diluted sample extracts (numbered 22 to 42) 17. Identify sample extracts (before dilution with test buffer) out of both runs which showed higher OD than OD value of standard 6 18. Repeat diluting these extracts 1:25 as described in 10. Sample extraction procedure subitem k) in this document; immediately further dilute these dilutions 1:5 using the cocktail/ethanol containing buffer described in 9. Prepare cocktail/ethanol containing dilution buffer in this document; immediately re‐test these further diluted samples as described in this chapter; document the position of each further diluted extract using the data return sheet Run 3. 19. Please document all results in the data return sheet. Document any changes to this protocol in the data return sheet as well and send the data return sheet to the Study Director (k.scherf.leibniz‐lsb@tum.de) Outliers 1. If analytical results appear unreasonable (CVs > 15% for the same extract in the two wells for samples with ODs higher than standard 2, for example) investigate possible cause immediately, first by checking for transcription and pipetting errors. Call the Study Director to discuss suspicious values. If the Study Director indicates the value may be an outlier, re‐ analyze the suspected sample. In case of retesting, dilute the sample extract again 1:25 in buffer (see 10 k. in this document) 2. Since collaborators have no basis for judging whether a value is an outlier, all OD values should be communicated to the Study Director as soon as possible, and before time and equipment are re‐assigned, so that repeat assays maybe performed if necessary. 3. Results can be communicated to the Study Director preferably by e‐mail (preferred). 4. Correctable Outliers – The most frequent causes of correctable outliers are: a. Pipetting errors b. Errors in reporting, such as transposition errors, misplacement of decimal point, or use of the wrong units. c. Contamination of reagents, equipment, or test materials Data Review and Reporting Upon receipt of data from all the collaborators, the Study Director will compile data, calculate all concentrations, conduct preliminary statistical analysis, and write the collaborative study report. The report is submitted to the Committee Statistician for review, and is then forwarded to the Expert Review Panel (ERP) for gluten. The ERP reviews the study report and then submits the study to the Official Methods Board, who can then adopt the method as an Official Method of Analysis First Action. If so adopted the collaborative study is published in the Journal of AOAC INTERNATIONAL, in which you will receive credit as a collaborator. The AOAC Official Method is published in the “Official Methods of Analysis”. Regardless of the outcome of the study, a compilation of the study will be forwarded to you, with your results highlighted.
Thank you very much in advance for your participation in this study. We highly appreciate your contribution.
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