byby Scott R. Oulton, SWGDRUG Secretariat Scientific Working Group for the Analysis of Seized Drugs Update
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 2) SWGDRUG Recommendations 5 th Edition (revised/edited current recommendations) Current work projects and future topics Four active subcommittees (uncertainty, editorial, education and training and CLIC collaboration)
Supplemental Document SD-3 for Part IVC “Examples of Measurement Uncertainty for Weight Determinations” Supplemental Document SD-3 for Part IVC “Examples of Measurement Uncertainty for Weight Determinations”
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 2010 Currently, the document is being vetted through NIST for a final review prior to posting UNCERTAINTY SUBCOMMITTEE
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 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 SUPPLEMENTAL DOCUMENT SD-3
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 FACTORS CONSIDERED
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: o calibrated and certified o being used above the established minimum balance load o performing within manufacturer specifications o located in a temperature-controlled environment (±5 °C) EXAMPLE SCENARIO
A weigh vessel is: loaded and tared removed and filled with powder reweighed containing powder Net weight = 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 EXAMPLE SCENARIO
Expanded Uncertainty U = k * u c Using Coverage Factor (k) = 2 (approx. 95%) U = 2 * g = g Final U final = U * # weighing events U final = g * 2 = g CALCULATION
Results Net Weight: g ± 0.07 g (k=2) Net Weight: g ± 0.11 g (k=3) RESULTS
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
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 o 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 WHAT NEXT?
SWGDRUG Recommendations 5 th Edition SWGDRUG Recommendations 5 th Edition
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 EDITORIAL COMMITTEE
§ 2Education and experience for analysts Before: o 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 o by January 1, 2005, a minimum of five (5) years practical experience in the area of seized drug analysis… SIGNIFICANT CHANGES
§ 2Education and experience for analysts After: o 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. SIGNIFICANT CHANGES
§ 3 Continuing professional development Before: o 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: o 3.4 Training can be either face-to-face interaction with an instructor, distance learning, self-directed or computer based. Added: current literature review SIGNIFICANT CHANGES
§ 11 Analytical method validation and verification Before: o 11.1 Method validation is required to demonstrate that methods are suitable for their intended purpose. For qualitative analysis, the parameters that need to be checked are selectivity, limit of detection and reproducibility. Minimum acceptability criteria should be described along with means for demonstrating compliance. Validation documentation is required. o 11.2 Laboratories adopting methods validated elsewhere should verify these methods and establish their own limits of detection and reproducibility. After: o Method validation is required to demonstrate that methods are suitable for their intended purpose (see PART IV B – Validation). PART IV B – ValidationPART IV B – Validation 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.) 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 :2006, VIM 2008 Category A now includes: X-Ray Diffractometry SIGNIFICANT CHANGES
Before § 3.1… Use second technique … § 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. 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 o Second sampling o Procedural blank o Witnessing SIGNIFICANT CHANGES
After The laboratory shall employ quality assurance measures to ensure the results correspond to the exhibit. Example measures are: o the use of two separate samplings o sample identification procedures such as bar- coding and witness checks o good laboratory practices (e.g., positive and negative controls, one sample opened at a time, procedural blanks) 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. SIGNIFICANT CHANGES
Solution Examples of diminished discriminating power may include: o an infrared spectroscopy technique applied to a mixture which produces a combined spectrum o a mass spectrometry technique which only produces molecular weight information SIGNIFICANT CHANGES
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 Develop comprehensive training program o On-line program – web based o Hypertext linking o Downloadable o Use in conjunction with identified references EDUCATION AND TRAINING SUBCOMMITTEE
What’s Next for SWGDRUG?
WHAT’s NEXT for SWGDRUG? Four Active Subcommittees 1) Uncertainty Subcommittee* 2) Education and Training Subcommittee* 3) Reporting Subcommittee Revise/Edit/Develop Reporting Recommendations Consider 2009 NAS report and ISO ) Coordination with CLIC Developing standards for the analysis of clandestine drug laboratory samples
SWGDRUG Core Committee
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 – Vacant Educator – Dr. Suzanne Bell
CORE COMMITTEE CAC & NWAFS – Jerry Massetti MAFS – Richard Paulas MAAFS – Linda Jackson SAFS – Christian Matchett SWAFS – Scott Vajdos AAFS – Dr. Sandra Rodriguez-Cruz Toxicology – Dr. Robert Powers
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
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