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Qaqc Course Total


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Qaqc Course Total

  1. 1. Quality is a Lousy Idea- If it’s Only an Idea
  2. 2. Quality Assurance vs. Quality Control Quality Assurance An overall management plan to guarantee the integrity of data (The “system”) Quality Control A series of analytical measurements used to assess the quality of the analytical data (The “tools”)
  3. 3. True Value vs. Measured Value <ul><li>True Value </li></ul><ul><li>The known, accepted value of a quantifiable property </li></ul><ul><li>Measured Value </li></ul><ul><li>The result of an individual’s measurement of a quantifiable property </li></ul>
  4. 4. Accuracy vs. Precision <ul><li>Accuracy </li></ul><ul><li>How well a measurement agrees with an accepted value </li></ul><ul><li>Precision </li></ul><ul><li>How well a series of measurements agree with each other </li></ul>
  5. 5. Accuracy vs. Precision
  6. 6. Systematic vs. Random Errors <ul><li>Systematic Error </li></ul><ul><li>Avoidable error due to controllable variables in a measurement. </li></ul><ul><li>Random Errors </li></ul><ul><li>Unavoidable errors that are always present in any measurement. Impossible to eliminate </li></ul>
  7. 7. Quality Control Measures <ul><li>Standards and Calibration </li></ul><ul><li>Blanks </li></ul><ul><li>Recovery Studies </li></ul><ul><li>Precision and Accuracy Studies </li></ul><ul><li>Method Detection Limits </li></ul><ul><li>NJQLs </li></ul>
  8. 8. Standards and Calibration <ul><li>Prepared vs. Purchased Standard </li></ul><ul><li>Signals: Peak Area, Beer’s Law </li></ul><ul><li>Calibration Curves </li></ul><ul><li>Continuing Calibration Checks </li></ul><ul><li>Internal Standards </li></ul><ul><li>Performance Testing . </li></ul>
  9. 9. Calibration Curves <ul><li>Graphical representation of the relationship between: </li></ul><ul><ul><li>The analytical signal </li></ul></ul><ul><li>The concentration of the analyte </li></ul>and
  10. 11. Continuing Calibration Verification <ul><li>Many methods don’t require that daily calibration curves are prepared </li></ul><ul><li>A “calibration verification” is </li></ul><ul><li>analyzed with each batch of samples </li></ul>
  11. 12. Sample Batch <ul><li>10 - 20 samples (method defined) or less </li></ul><ul><li>Same matrix </li></ul><ul><li>Same sample prep and analysis </li></ul><ul><li>Contains a full set of </li></ul><ul><li>QC samples </li></ul>
  12. 13. Internal Standards <ul><li>A compound chemically similar to the analyte </li></ul><ul><li>Not expected to be present in the sample </li></ul><ul><li>Cannot interfere in the analysis </li></ul><ul><li>Added to the calibration standards and to the samples in identical amounts . </li></ul>
  13. 14. Internal Standards <ul><li>Refines the calibration process </li></ul><ul><li>Analytical signals for calibration standards are compared to those for internal standards </li></ul><ul><li>Eliminates differences in random and systematic errors between samples and standards </li></ul>
  14. 15. Performance Testing <ul><li>Blind samples submitted to laboratories </li></ul>? ? ? Labs must periodically analyze with acceptable results in order to maintain accreditation
  15. 16. Blanks, Blanks, Blanks <ul><li>Laboratory Reagent Blanks </li></ul><ul><li>Instrument Blanks </li></ul><ul><li>Field Reagent Blanks </li></ul><ul><li>Trip Blanks </li></ul>
  16. 17. Laboratory Reagent Blanks <ul><li>Contains every reagent used in the analysis </li></ul><ul><li>Is subjected to all analytical procedures </li></ul><ul><li>Must give signal below detection limit </li></ul><ul><li>Most methods require one with every batch </li></ul>
  17. 18. Instrument Blank <ul><li>A clean sample (e.g., distilled water) processed through the instrumental steps of the measurement process; used to determine instrument contamination. </li></ul>
  18. 19. Field Reagent Blanks <ul><li>Prepared in the lab, taken to the field </li></ul><ul><li>Opened at the sampling site, exposed to sampling equipment, returned to the lab. </li></ul>
  19. 20. Trip Blanks <ul><li>Prepared in the lab, taken to the field </li></ul><ul><li>Not opened </li></ul><ul><li>Returned to the lab </li></ul><ul><li>Not always required in EPA methods </li></ul>
  20. 21. Recovery Studies <ul><li>Matrix Spikes </li></ul><ul><li>Laboratory Control Samples </li></ul><ul><li>Surrogates . </li></ul>
  21. 22. Matrix Spikes <ul><li>Sample spiked with a known amount of analyte </li></ul><ul><li>Subjected to all sample prep and analytical procedures </li></ul><ul><li>Determines the effect of the matrix on analyte recovery </li></ul><ul><li>Normally one per batch </li></ul>
  22. 23. Laboratory Control Sample <ul><li>Subjected to all sample prep and </li></ul><ul><li>analytical procedures </li></ul><ul><li>Analyte spiked into reagent water </li></ul>
  23. 24. Laboratory Control Sample <ul><li>Also known as: </li></ul><ul><li>Laboratory Fortified Blank (LFB) </li></ul><ul><li>Quality Control Sample (QCS) </li></ul>
  24. 25. Surrogates <ul><li>Similar to an internal standard </li></ul><ul><li>Added to all analytical samples, and to all QC samples to monitor method performance, usually during sample prep </li></ul><ul><li>Methods often have specific surrogate recovery criteria </li></ul><ul><li>Most common in Organic methods </li></ul>
  25. 26. Quality Control Measures <ul><li>Standards and Calibration </li></ul><ul><li>Blanks </li></ul><ul><li>Recovery Studies </li></ul><ul><li>Precision and Accuracy Studies </li></ul><ul><li>Method Detection Limits </li></ul><ul><li>NJQLs </li></ul>
  26. 27. Precision and Accuracy <ul><li>Required for initial certification and annually thereafter </li></ul><ul><li>A series of four laboratory control samples </li></ul><ul><li>Must meet accuracy (recovery) and precision (standard deviation) requirements, often in method </li></ul>
  27. 28. Precision and Accuracy <ul><li>Required with a change in instrumentation or personnel </li></ul><ul><li>Specific to the analyst </li></ul><ul><li>Other names include: </li></ul><ul><li> P&A, DOC, IDOC </li></ul>
  28. 29. Method Detection Lim it <ul><li>“ The minimum concentration of a substance that can be measured and reported with 99% confidence that the analyte concentration is greater than zero” </li></ul><ul><li> N.J.A.C 7:18 - 1.7 </li></ul>
  29. 30. Method Detection Limit <ul><li>MDLs are determined according to 40 CFR, part 136, Appendix B </li></ul><ul><li>Seven replicate laboratory control samples, analyzed for precision </li></ul><ul><li>Multiply standard deviation by 3.14 (Student’s t- value) </li></ul>
  30. 31. Method Detection Limit <ul><li>Must be performed initially for certification </li></ul><ul><li>Must meet criteria specified in method </li></ul><ul><li>Must be performed with change in instrumentation or test method </li></ul><ul><li>Annually with ELCP </li></ul>
  31. 32. New Jersey Quantitation Limits (NJQLs) <ul><li>The minimum concentration of an analyte that can be quantified with statistical confidence </li></ul><ul><li>5 x MDL, for the NJ Lab Certification Program </li></ul>