1 / 41

Scott R. Oulton, SWGDRUG Secretariat

Scientific Working Group for the Analysis of Seized Drugs Update. by. Scott R. Oulton, SWGDRUG Secretariat. OVERVIEW. In January 2010, the core committee approved two documents: 1) Supplemental Document SD-3 For Part IVC – Examples of Measurement Uncertainty for Weight Determinations

nysa
Download Presentation

Scott R. Oulton, SWGDRUG Secretariat

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Scientific Working Group for the Analysis of Seized Drugs Update by Scott R. Oulton, SWGDRUG Secretariat

  2. OVERVIEW • In January 2010, the core committee approved two documents: 1) Supplemental Document SD-3 For Part IVC – Examplesof Measurement Uncertainty for Weight Determinations 2) SWGDRUG Recommendations 5th Edition (revised/edited current recommendations) • Current work projects and future topics • Four active subcommittees (uncertainty, editorial, education and training and CLIC collaboration) • Proposed change to reporting requirements • New initiatives

  3. Supplemental Document SD-3 for Part IVC “Examples of Measurement Uncertainty for Weight Determinations”

  4. SUPPLEMENTAL DOCUMENTS • Supplemental Documents • Intended to be a resource for those implementing recommendations • Not all inclusive, many ways to implement recommendations • Purpose is to provide examples to be used in conjunction with SWGDRUG Recommendations

  5. UNCERTAINTY SUBCOMMITTEE The draft supplemental document was posted for public comment in July 2009 Many comments were received The document was vetted through professional metrologists and statisticians Supplemental Document SD-3 was adopted January and posted in July 2010

  6. SUPPLEMENTAL DOCUMENT SD-3 • Type A – statistically determined from repetitive measurements (e.g., control chart) • Type B – everything else (e.g., calibration report) • Three examples were developed • Example 1: 1 bag of powder (type B uncertainties) • Example 2: 1 bag of powder (type A -B uncertainties) • Example 3: 15 bags of powder (type A -B uncertainties) • In Example 1, five significant uncertainty sources were considered. For example 2 & 3, data from a well-established control chart captures three of these factors

  7. SUPPLEMENTAL DOCUMENT SD-3 • Multiple approaches exist for estimating uncertainties • Elements used contain correlated and uncorrelated sources • The illustrated methods in these examples represent a conservative approach in which the uncertainty is likely to be overestimated • This is done to conservatively account for all correlations even those that for all practical purposes cannot be determined

  8. FACTORS CONSIDERED Readability Repeatability Linearity Buoyancy (insignificant) Sensitivity (insignificant) Uncertainty from balance calibration Number of weighing events Sample loss in transfer: for practical purposes, this is considered indeterminate and irrelevant

  9. EXAMPLE SCENARIO • Determine net weight of a white powder received in a plastic bag using a top loading balance. The following conditions apply: • The operator is competent on the use of the balance • The balance is: • calibrated and certified • being used above the established minimum balance load • performing within manufacturer specifications • located in a temperature-controlled environment (±5 °C)

  10. EXAMPLE SCENARIO • A weigh vessel is: • loaded and tared • removed and filled with powder • reweighed containing powder • Net weight = 30.03 grams • Static weighing – obtaining net weight via two weighing operations • Two weighing events • Dynamic weighing – adding powder directly to tared vessel on balance • One weighing event

  11. CALCULATION Expanded Uncertainty U = k * uc Using Coverage Factor (k) = 2 (approx. 95%) U = 2 * 0.0176 g = 0.0352 g Final Ufinal = U * # weighing events Ufinal= 0.0352 g * 2 = 0.0704 g

  12. RESULTS • Results • NetWeight: 30.03 g ± 0.07 g (k=2) • NetWeight: 30.03 g ± 0.11 g (k=3)

  13. WHAT NEXT? • Uncertainty estimates associated with quantitative measurements • e.g., 82.4% ± 3.2% • Extrapolations of weights • Weight determined by statistically measuring a set amount of sub items • e.g., 10 out of 500 bricks of cocaine weighed and extrapolated to calculate total weight of 500 kg. The uncertainty is estimated based on statistical analysis of 10 weighed units

  14. SWGDRUG Recommendations 5th Edition

  15. EDITORIAL COMMITTEE • Goal – Revision of existing SWGDRUG Recommendations to: • Harmonize terminology • Correct grammar • Add references • Link sections • Correct sections in conflict • Clarify recommendations as appropriate • Update glossary

  16. SIGNIFICANT CHANGES § 2 Education and experience for analysts • Before: • a bachelor’s degree (or equivalent, generally a three to four year post-secondary or tertiary degree) in a natural science or in other sciences relevant to the analysis of seized drugs… OR • by January 1, 2005, a minimum of five (5) years practical experience in the area of seized drug analysis…

  17. SIGNIFICANT CHANGES § 2 Education and experience for analysts • After: • All new analysts shall have at least a bachelor’s degree (or equivalent, generally a three to four year post-secondary degree) in a natural/physical science.

  18. SIGNIFICANT CHANGES § 3 Continuing professional development • Before: • Contact is defined as face-to-face interaction with an instructor or trainer in a classroom or laboratory setting. It does not include self-paced learning or distance education where the instructor has no active interaction with the student. • After: • 3.4 Training can be either face-to-face interaction with an instructor, distance learning, self-directed or computer based. • Added: current literature review

  19. SIGNIFICANT CHANGES § 11 Analytical method validation and verification • Before: • 11.1 Method validation is required to demonstrate that methods are suitable for their intended purpose. • 11.1.1 For qualitative analysis, the parameters that need to be checked are selectivity, limit of detection and reproducibility. • 11.1.2 Minimum acceptability criteria should be described along with means for demonstrating compliance. • 11.1.3 Validation documentation is required. • 11.2 Laboratories adopting methods validated elsewhere should verify these methods and establish their own limits of detection and reproducibility. • After: • Method validation is required to demonstrate that methods are suitable for their intended purpose (see PART IV B – Validation).

  20. SIGNIFICANT CHANGES • Added hyperlinks to Uncertainty section throughout document • Added hyperlinks to Validation section throughout document • Added “Shall” in place of “Should” in several locations (conduct, ethics, education, etc.)

  21. SIGNIFICANT CHANGES • Revisions to Glossary: • Added definition for “false negative” • Updated several definitions as a result of some ISO terms amended within the last few years • e.g., ISO 3534-2:2006, VIM 2008 • Category A now includes: X-Ray Diffractometry

  22. SIGNIFICANT CHANGES • Before § 3.1 … Use second technique … § 3.1.2 When sample size allows, the second technique should be applied on a separate sampling for quality assurance reasons. When sample size is limited, additional measures should be taken to assure that the results correspond to the correct sample. § 3.4 In cases where hyphenated techniques are used (e.g. gas chromatography-mass spectrometry, liquid chromatography-diode array ultraviolet spectroscopy), they will be considered as separate techniques provided that the results from each are used.

  23. SIGNIFICANT CHANGES • Problem • If two samplings important, why have different procedure for trace samples? • Misinterpretation of 3.4, hyphenated techniques do not offer second sampling • Solution • Revise section to emphasize quality assurance step • Second sampling • Procedural blank • Witnessing

  24. SIGNIFICANT CHANGES • After • The laboratory shall employ quality assurance measures to ensure the results correspond to the exhibit. Example measures are: • the use oftwo separate samplings • sample identification procedures such as bar-coding and witness checks • good laboratory practices (e.g., positive and negative controls, one sample opened at a time, procedural blanks)

  25. SIGNIFICANT CHANGES • Problem • e.g., Is DART a Category A or B? • Solution • Techniques for the analysis of drug samples are classified into three categories based on their maximum potential discriminating power. However, the classification of a technique may be lower, if the sample, analyte or mode of operation diminishes its discriminating power.

  26. SIGNIFICANT CHANGES • Solution • Examples of diminished discriminating power may include: • an infrared spectroscopy technique applied to a mixture which produces a combined spectrum • a mass spectrometry technique which only produces molecular weight information

  27. Education and Training Subcommittee

  28. EDUCATION AND TRAINING SUBCOMMITTEE • Phase 1 • Develop core competencies (outline form) • Coordinate efforts with ENFSI Drugs Working Group • Phase 2 • Identify existing resources (open source, for purchase, etc.) • Phase 3 • Post example training programs on-line

  29. Proposed Revision to Reporting Requirements

  30. Why Change Reporting? • Mirror ISO/IEC-17025 Language • NAS • Transparency

  31. Report Writing 9.2 Report writing Reports issued by laboratories shall be accurate, clear, objective, and meet the requirements of the jurisdictions served. Unless the laboratory has reasons for not doing so, these reports shall include the following information: • title of report • identity and location of the testing laboratory • unique case identifier (on each page) • clear identification of the end of the report • submitting agency • date of receipt • date of report • descriptive list of submitted evidence • identity and signature (or electronic equivalent) of analyst • results / conclusions • analytical techniques employed • sampling • uncertainty.

  32. Survey Results • 116 Responses • For – 38% • Against – 62% • Most commons reasons against proposal • Analytical Techniques • Sampling • Uncertainty • Cited reasons • Courts would not understand • Defense attorneys would have a field day • Would have to testify more

  33. Survey Results • Analytical Techniques • Presumptive test only, qualitative determination • Sampling • Tested 1 unit, report all containing • Uncertainty • Enhances confidence through increased understanding of results • e.g., Gas pump accuracy for 10 gallons • Gas Station 1: 10 ± 0.03 gal • Gas Station 2: 10 ± 1.35 gal • Near statutory threshold • Blood alcohol 0.08

  34. Survey Results SWGDRUG 9.2 Report writing Reports issued by laboratories shall be accurate, clear, objective, and meet the requirements of the jurisdictions served. Unless the laboratory has reasons for not doing so, these reports shall include the following information: ISO 17025 5.10.2 Each test report or calibration certificate shall include at least the following information, unless the laboratory has valid reasons for not doing so:

  35. New Initiatives

  36. New Initiatives • Formal Survey • Assess implementation of recommendations in the forensic science community • Using www.surveymonkey.com • MS Database • Contains over 1200 compounds • Inviting community to participate • Cooperation with CLIC • Developing recommendations for analysis of clandestine laboratory samples • Development of uncertainty spreadsheet

  37. SWGDRUG Core Committee

  38. CORE COMMITTEE • DEA – Scott Oulton (Chair) • Secretariat – Sandra Rodriguez-Cruz • FBI - Eileen Waninger • ASCLD – Garth Glassburg • NIST – Susan Ballou • ASTM and NEAFS – Jack Mario • Educator – Vacant (Eric Person) • Educator – Dr. Suzanne Bell

  39. CORE COMMITTEE • CAC & NWAFS – Jerry Massetti • MAFS – Richard Paulas • MAAFS – Linda Jackson • SAFS – Christian Matchett • SWAFS – Scott Vajdos • Toxicology – Dr. Robert Powers

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

  41. Visit us at: www.swgdrug.org

More Related