Method Selection - Selection of a prospective method for day to day laboratory use
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The document outlines the essential steps for method selection in analytical biochemistry, focusing on the evaluation of performance characteristics such as precision, accuracy, analytical range, detection limit, and specificity. It emphasizes the importance of method verification, validation, and quality control practices in laboratory settings, along with the necessity of establishing a startup phase for troubleshooting and training. Additionally, it discusses the analytical procedures for determining the accuracy and precision of methods through comparative analyses and statistical measures.
Method Selection - Selection of a prospective method for day to day laboratory use
- 1. Karthik G Kamath K Associate Professor Department of Biochemistry
- 2. Optimal method selection involves consideration of medical need, analytical performance, and practical criteria
- 3. In evaluation of the performance characteristics of a candidate method (1) precision, (2) accuracy (trueness), (3) analytical range, (4) detection limit, and (5) analytical specificity are of prime importance.
- 4. Establish need Definition of quality goal Method selection/development Method verification/ validation Implementation Routine analysis Quality control practices Result report
- 5. water quality, calibration of analytical balances, calibration of volumetric glassware and pipettes etc should be monitored on a laboratory-wide basis because they will affect many of the methods used in the laboratory
- 6. initial evaluation of a method often takes place in a setting somewhat more idealized than the production setting
- 7. it is desirable to have a startup laboratory before test results are to be reported. This period allows time to (1) discover any additional problems, (2) develop maintenance programs that alleviate those problems, and (3) train a sufficient number of analysts to support the routine service operation.
- 8. Measure of degree to which a curve approximates a straight line Refers to overall system response An attribute that is distinct for accuracy and precision Measured by testing levels of an analyte that are known relative to each other When results are plotted against these values the degree of curve’s comformance to straight line
- 9. Using samples containing analyte at 5 diff concentration levels in 3x A plot of signals is created, usually by means of regression line Correlation coefficient, y-intercept, slope, and residual sum of squares must be calculated.
- 10. Several methods are available application of an analytical procedure to an analyte of known purity (e.g. reference material) comparison of the results of the proposed analytical procedure with those of a second well-characterised procedure, the accuracy of which is stated and/or defined 2 results must be compared accuracy may be inferred once precision, linearity and specificity have been established.
- 11. Repeatability – A min. 9 determinations covering specified range of procedure (3 concentrations / 3 replicates) A min. 6 determinations at 100% of the test concentration (the theoretical concentration of a testing substance when you prepare a test solution)
- 12. Reproducibility – By inter-laboratory trials (testing same sample by many laboratories) Standardization of an analytical procedure
- 13. Tietz textbook of Clinical chemistry and molecular diagnostics Wikipedia.org Slideshare.net Other internet resources