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2007/2008 SWGDRUG ACCOMPLISHMENTS PowerPoint Presentation
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  1. 2007/2008 SWGDRUG ACCOMPLISHMENTS sponsored by the Drug Enforcement Administration Office of Forensic Sciences and the National Institute of Standards and Technology

  2. SWGDRUG Scientific Working Group for the Analysis of Seized Drugs

  3. WHY UNCERTAINTY NEXT? • Forensic community asking for guidance • Accrediting bodies establishing measures of assessing conformity with ISO • Customer requirements • Jurisdictional requirements • Transparency (nothing to hide) • Potential Exculpatory Information

  4. Uncertainty Document • The core committee voted in January 2008 to release the draft uncertainty document for public comment • Posted on the website since February 2008 • The SWGDRUG meeting was held July 21-23, 2008 in New Orleans, LA • Comments were addressed and the core committee voted to adopt the document on July 22, 2008 • The document should be posted on the website by the end of August 2008

  5. SWGDRUG APPROACH TO UNCERTAINTY • There is a wealth of information that already exists on Uncertainty • No intentions of repeating existing information • Goal is to tailor the recommendations to drug analysis and answer specific uncertainty questions • Answer specific drug analysis uncertainty questions, before others do • Offer guidance and direction to laboratories and accrediting bodies

  6. WHY? • Provide Purpose/Guidance • Uncertainty is associated with both qualitative and quantitative procedures • Raise Awareness • Uncertainty is not doubt, it provides assurance that results and conclusions are fit for purpose • Laboratory Responsibility • Consider customer requirements and address uncertainty through training, procedures and documentation • Benefits • Enhanced confidence through increased understanding of results • Provides Mechanism to express reliability of results

  7. HOW? • Two Primary Sections • Qualitative • Quantitative • Purity • Weights

  8. QUALITATIVE • Individual methods have limitations and, consequently, uncertainty • Understanding limitations allows analysts to build an appropriate analytical scheme to correctly ID drugs or chemicals • It is expected that an appropriate analytical scheme will result in, effectively, no uncertainty in reported identifications • Relevant limitations of an analytical scheme should be documented and may need to be in report

  9. QUALITATIVE EXAMPLES • Use Part III B Methods of Analysis/Drug Identification • IR and microcrystalline test positive for cocaine – effectively NO uncertainty • Limitations • Marquis test positive for methamphetamine – could be methamphetamine or other amphetamines • GC/MS test positive for ephedrine – could be ephedrine or pseudoephedrine

  10. QUANTITATIVE • Uncertainty is defined as an estimate attached to a test result which characterizes the range of values within which the true value is asserted to lie • Precise calculations of measurement uncertainty is not always required

  11. QUANTITATIVE CONT. • Primary numerical values reported in the analysis of seized drugs are • Weight and Purity • Where a value is critical, an appropriate measurement uncertainty determination shall be applied • Weight close to a statutory threshold • Purity of drug affects sentencing

  12. WEIGHT • Uncertainty of a reported value is dependant on the weighing process. Factors include: • Single item versus multiple items (# of weighing operations) • Tare function as separate weighing operation • Extrapolation of population weight from limited sampling of multiple items • Aggregate weighings • Incomplete recovery of material from packaging • Balance selection (e.g., readability, capacity) • Balance operation (e.g., sample placement, environmental conditions)

  13. PURITY • Sources of uncertainty for purity determination • Sampling plan (e.g., handling of multiple exhibits) • Sample homogeneity • Analytical method • Sample preparation (e.g., size, matrix effects, solubility) • Analytical technique • Reference material (e.g., purity of standard) • Equipment and instrumentation performance (e.g., glassware, pipetters, balances, chromatographs) • Concentration of analyte • Environmental conditions

  14. PURITY APPROACHES • Analytical Error • Address both systematic and random error through method validation and quality assurance • Sampling Error • The sample and sampling procedure are often the greatest contributors to measurement uncertainty • Where appropriate, confidence levels (e.g., 95%) shall be selected based on considerations relevant to the analytical context • Record uncertainty information in validation documents and/or case records

  15. UNCERTAINTY BUDGET • All sources of error are separately identified and tabulated • Assign values to each error source using • Empirical data • Validation process, Historical performance data, Control chart data, proficiency tests • Published data • Combination of empirical and published data • Can exclude insignificant sources • Calculate combined and expanded uncertainty using significant values for procedure

  16. NON-BUDGET APPROACH • Example 1: Use of data from replicate analyses from a validated method with an appropriate sampling plan • Sources of uncertainty that are separately assessed in the budget method are collectively assessed by experimental measurements • Example 2: Use of two standard deviations (2σ) of the test method results from reproducibility data from the validation studies. • Provides an approximation of the measurement uncertainty for non-critical values

  17. WHEN? • Reporting of measurement uncertainty • Uncertainty shall be documented but may not need to be reported • Should be reported when result impacts customer • If not reported, analysts shall be cognizant of the uncertainty associated with their results

  18. REPORTING • Factors to consider when reporting: • Jurisdictional • Prevailing statutory requirement • Relevant governing body (agency) requirements • Customer requests • Potential exculpatory value • Analytical • Qualitative results where limitations are known (e.g., inability to differentiate isomers) • Quantitative measurements where a value is critical (e.g., weight or purity level close to statutory threshold) • Laboratory accreditation requirements

  19. REPORTING EXAMPLES • Qualitative: • Contains Ephedrine or Pseudoephedrine. Item tested: 5.2 grams net • Visual examination determined that the physical characteristics are consistent with a Schedule IV pharmaceutical preparation containing Diazepam. There was no apparent tampering of the dosage unit and no further tests are being conducted. • Contains cocaine (salt form not determined)

  20. REPORTING EXAMPLES • Quantitative: • Positive for cocaine in the sample tested Net weight of total sample: 5.23 grams ± 0.03 grams Quantitation: 54.7% ± 2.8% • Sample tested positive for cocaine Net weight: 5.23 grams Purity: 54.7% Confidence Range: ± 2.8%* Calculated net weight of drug: 2.8 grams of cocaine *Confidence range refers to a 95% confidence level

  21. TRAINING • Individuals responsible for determining, evaluating and documenting uncertainty shall be capable of demonstrating familiarity with foundational concepts and principles of estimating uncertainty • General metrology (terminology, symbols, etc.) • Concepts of random and systematic error, accuracy, precision, propagation of error, etc. • Reporting conventions (sig. figs, truncating, rounding) • Basis statistics (i.e., confidence interval, probability, etc) • Analysts shall be capable of explaining their labs procedures for evaluating uncertainty of qualitative and quantitative analyses

  22. SUPPLEMENTAL DOCUMENTS TO FOLLOW • Control chart data method • Demonstration of balance control using standard weight sets • Summing weights from individual exhibits • Expression of sampling uncertainty based on confidence interval using multiple samplings • Uncertainty budget

  23. CORE COMMITTEE • DEA – Nelson Santos (Chair) • Secretariat – Scott Oulton (non-voting) • FBI - Eileen Waninger • ASCLD – Garth Glassburg • NIST - Susan Ballou • ASTM and NEAFS- Jack Mario • Educator – Dr. Chris Tindall • Educator – Dr. Suzanne Bell

  24. CORE COMMITTEE • CAC & NWAFS - Jerry Massetti • MAFS - Richard Paulas • MAAFS - Linda Jackson • SAFS – Christian Matchett • Toxicology – Dr. Robert Powers

  25. CORE COMMITTEE • Canada - Richard Laing • Japan – Mr. Osamu Ohtsuru • United Kingdom - Dr. Sylvia Burns • Australia - Catherine Quinn • Germany - Dr. Udo Zerell • ENFSI - Dr. Michael Bovens • UNODC - Dr. Iphigenia Naidis

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