1.1 Introduction:

The purpose of this document is to recommend minimum standards for the forensic identification of seized drugs. It is recognized that the correct identification of a drug or chemical depends on the use of an analytical scheme based on validated methods and the competence of the analyst. This document requires the use of multiple uncorrelated techniques. It does not discourage the use of any particular method within an analytical scheme. Unique requirements in different jurisdictions may dictate practices followed by a particular laboratory.

1.2 Categorizing Analytical Techniques:

For the purposes of this document, techniques for the analysis of drug samples may be broken down into three categories based on their discriminating power. Table 1 lists examples of such techniques, listed in order of decreasing discriminating power from A to C:

1.3 Recommended Practices:

SWGDRUG recommends that laboratories adhere to the following minimum standards:

1.3.1 When a Category A technique is incorporated into an analytical scheme, then at least one other technique (from either Category A, B or C) must be used. This combination must identify the specific drug present and must preclude a false positive identification. 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. All Category A techniques must have data that are reviewable.

1.3.2 When a Category A technique is not used, then at least three different validated methods must be employed. These in combination must demonstrate the identity of the specific drug present and must preclude a false positive identification. Two of the three methods must be based on uncorrelated  techniques from Category B. All Category B techniques must have reviewable data.  A minimum of two separate samplings should be used in these three tests.

1.3.3. For the use of any method to be considered of value, the test must be considered “positive.”  While “negative” tests provide useful information for ruling out the presence of a particular drug or drug class, these results have no value toward establishing the forensic identification of a drug.

1.3.4. In cases where hyphenated techniques are used (e.g. gas chromatography-mass spectrometry, liquid chromatography- ultraviolet spectrophotometry), they will be considered as separate techniques provided that the results from each are used.

1.3.5. Cannabis exhibits tend to have characteristics that are visually recognizable. Thus,  macroscopic and microscopic examinations of cannabis will each be considered as Category B techniques  when observations include documented details of botanical features. Additional testing must follow the scheme outlined in sections 1.3.1 or 1.3.2.

1.3.5.1.For exhibits of cannabis  that lack sufficient observable macroscopic and microscopic botanical detail (e.g. extracts or residues), delta-9-tetrahydrocannabinol (THC) must be identified utilizing the principles set forth in sections 1.3.1 and 1.3.2.

1.3.6. Some examples of reviewable data include printed spectra, chromatograms, and  photographs or photocopies of TLC plates. With regard to microcrystalline tests, contemporaneous documented peer review of the tests will suffice. Recording of detailed descriptions of morphological characteristics will be allowed for cannabis only.  Pharmaceutical identifiers need only be referenced to published data.

1.4 Final Comment:

It should be recognized that these are recommendations for minimum standards for identification of drugs. These recommendations may not be sufficient for identification of all drugs in all circumstances. Within these recommendations, it is up to the individual laboratory’s management to determine which combination of analytical techniques best satisfies the requirements of its jurisdiction.

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APPENDIX A

The following are examples of how a laboratory may choose to perform forensic drug identifications. These examples are not to imply that these are the “best” combinations to identify the listed drug. Instead, they demonstrate how different analytical combinations result in identification as recognized by SWGDRUG.

Example #1:

An unknown powder gives positive results for cocaine using the following methods:

Option #1
Cobalt Thiocyanate Spot Test:     (Category C)
FTIR Analysis:                                   (Category A)
Result                                       Cocaine Identified

Option #2
Cobalt Thiocyanate Spot Test:     (Category C)
Microcrystalline Test:                      (Category B)
TLC Analysis :                                   (Category B)
Result                                       Cocaine Identified
 
 

Example #2:

An unknown powder tests positive for heroin by the following methods:

Option #1
Marquis Spot Test:                       (Category C)
GC-MS Analysis:                           (Categories B + A)
Result                                    Heroin Identified

Option #2
TLC Analysis with UV visualization:                 (Category B)
Marquis Reagent detection on above plate:   (Category C)
GC Analysis:                                                            (Category B)
Result                                                         Heroin Identified
 
 

Example #3:

An exhibit (suspected to be cannabis) tests positive for cannabis by the following techniques:

Option #1 – Observable botanical features
Macroscopic Examination:                     (Category B)
Microscopic Analysis:                              (Category B)
Duquenois-Levine Analysis:                  (Category C)
Result                                              Cannabis Identified

Option #2 - No sufficient observable botanical features
Duquenois-Levine Analysis:                  (Category C)
GC-MS Analysis (for THC):                      (Categories B + A)
Result                                               THC Identified