Methods for impurity profiling of heroin and cocaine

Data handling, interpretation of results and data collections

49

bulk of the heroin and other alkaloidal bases are retained in the aqueous phase

while extracting many of the alkaloidal-related amidic compounds into an orga-

nic phase. High-resolution capillary gas chromatograms of these extracts are typi-

cally quite complex and many analysts have found that visual comparison of the

overlaid chromatograms is the most efficient direct comparison method (see annex

II, tables 1 and 2, for a listing of many of the known alkaloidal compounds found

in heroin and cocaine). 

B.

Interpretation of results

Irrespective of the equipment and software available in a laboratory carrying out,

or planning to carry out, impurity profiling, the results have to be interpreted care-

fully, taking all relevant considerations into account, including analytical impli-

cations of illicit processing and distribution, as well as those arising, for example,

from differences in storage conditions. Experience in the interpretation of profil-

ing results can only be built gradually, but good analytical skills and knowledge

of relevant chemistry are essential. In addition, for analytical results to be oper-

ationally useful, they have to be communicated in an adequate way to the request-

ing authority. The United Nations manual Drug Characterization/Impurity Profiling:

Background and Concepts [5] provides an overview of relevant practical aspects

related to the interpretation of results, addressing the following areas:

(a)

The significance of chemical similarities and differences between

drug samples;

(b)

Establishing specific links between two or more samples;

(c)

Establishing drug distribution patterns;

(d)

Identifying the source of drug samples:

(i)

Natural and semi-synthetic drugs;

(ii)

Synthetic drugs;

(e)

Identifying and characterizing the specific starting materials employed

in clandestine drug manufacture.

C.

Approach to setting up profiling data collections

As explained previously, the availability of appropriate databases is critical for

both types of comparison, case-to-case comparisons for evidential purposes and

retrospective comparisons for intelligence purposes. A recommended approach to

the compilation of a profiling data collection is as follows:

(a)

Generate a data bank of comparison data (i.e. analytical data plus any

appropriate physical data). (The samples used for generating compari-

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50

Methods for impurity profiling of heroin and cocaine

son data will depend on the purpose of the profiling work: it will be

day-to-day casework samples for a programme focusing on case-to-case

comparisons or a collection of appropriate samples from known sources

for a focus on determining sample origin);*

(b)

Determine those data points collected within the data bank which have

statistically useful comparison value;

(c)

Develop a search algorithm to identify possible “matches”. (Typically

either a relational database or spread sheet program is utilized. A sim-

ple search algorithm using peak area ratios of two to four of the statis-

tically useful major components will keep the search times to a minimum

and may be sufficient for this work);

(d)

Develop an enhanced search algorithm to extend comparison to other

statistically useful data points to include trace alkaloid-related compo-

nents. (As a first step in developing a profiling programme, comparison

of trace impurity profiles can be carried out by visual superimposition

of chromatograms);

(e)

Develop and define a statistically defensible method for determining the

probability that “matches” are made correctly. (The use of a commer-

cially available statistical software program can greatly simplify this

process).

Any database should be periodically re-evaluated to identify obvious outliers and

to ensure its appropriateness for the intended purpose. 

The process of building appropriate databases may be efficiently assisted by

the exchange of information and data, in a standardized form, between laboratories.

In conclusion, the methods and approaches published in this manual provide

guidance for the establishment of profiling programmes for heroin and/or cocaine.

As has already been noted, it is necessary for the analyst to understand exactly

how the impurity profiling results will be utilized and to know the precise nature

of all applicable requirements before attempting to set up an impurity profiling

programme and/or choosing the appropriate analytical methods. Irrespective of the

purpose, the importance of taking a comprehensive approach to profiling work

cannot be over emphasized.

*The accuracy of sample source assignments directly determines the limits of accuracy and quali-

ty of the profiling programme.

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51

References

1. “Report of an expert group: the feasibility of using chemical characteristics for iden-

tifying sources of heroin and for tracking its movement in the illicit traffic, Hong Kong,

17-21 October 1977” (MNAR/8/1977).

2. “Report of the expert group to coordinate research on the physical and chemical 

characteristics of heroin to trace its origin and movement in the illicit traffic”

(E/CN.7/1983/2/Add.4).

3. “Report of the consultative meeting on chemical characterization/profiling of drug

seizures, Vienna, 30 November-2 December 1992”.

4. Official Records of the Economic and Social Council, 1996, Supplement No. 7

(E/1996/27), chap. XIV, resolution I (XXXIX).

5. Drug Characterization/Impurity Profiling: Background and Concepts; Manual for Use

by National Law Enforcement Authorities and Drug Testing Laboratories (United

Nations publication, Sales No. E.01.XI.10) [ST/NAR/32/Rev.1, 2001].

6. United Nations, Recommended Methods for Testing Opium, Morphine and Heroin:

Manual for Use by National Drug Testing Laboratories (ST/NAR/29/Rev.1) [1998].

7. United Nations, Recommended Methods for Testing Cocaine: Manual for Use by

National Narcotics Laboratories (ST/NAR/7) [1987].

8. A. Roßmann and H.-L. Schmidt, “Assignment of ethanol origin and proof of sugar

addition to wine through positional 

2

H and 

13

C isotope ratio measurement”, Zeitschrift

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13

C IRMS”, Analytica Chimica Acta, vol. 347, No. 3

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11. B.-L. Zhang and others, “Characterization of glycerol from different origins by 

2

H- and

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and Food Chemistry, vol. 46, No. 4 (1998), pp. 1374-1380.

12. A. M. Pupin and others, “Use of isotopic analyses to determine the authenticity of

Brazilian orange juice (Citrus sinensis)”, Journal of Agricultural and Food Chemistry,

vol. 46, No. 4 (1998), pp. 1369-1373.

13. J. Gonzalez and others, “Authentication of lemon juices and concentrates by a com-

bined multi-isotope approach using SNIF-NMR and IRMS”, Journal of Agricultural

and Food Chemistry, vol. 46, No. 6 (1998), pp. 2200-2205.

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