methods for impurity profiling of heroin and cocaine - United Nations ...

Introduction 3
on the detection and assay of various groups of drugs in biological specimens,
can be requested from the Laboratory and Scientific Section (see address below).
Copies of articles from the scientific literature on drug characterization and impurity
profiling can also be requested from the same address.
It is important to note that these manuals are provided to laboratories as educational
documents within the training remit of UNODC and as a means of encouraging
laboratories to collaborate and participate with the United Nations in the
global effort to combat illicit drugs. In addition, these publications are also an
attempt to help promote national efforts by providing internationally accepted
guidelines.
C. Use of the manual
The present manual, as was the case with previous manuals, suggests approaches
that may assist drug analysts in the selection of methods appropriate to the
sample under examination and provide data suitable for the purpose at hand. The
majority of methods described here are published in the scientific literature. They
represent a summary of the experience of scientists from several reputable laboratories
around the world and have been routinely used for a number of years in
those laboratories. The reader should be aware, however, that there are a number
of other published methods not mentioned in this manual that may also produce
acceptable results. There are a number of more sophisticated additional approaches
that may provide insight into specific aspects of sample history, but may not be
necessary for routine operational applications. Therefore, the methods described
here should be understood as guidance, that is, minor modifications to suit local
circumstances should normally not change the validity of the results.
Methods provided here are chosen on the basis of proven suitability and reliability,
important prerequisites, especially if the results are to be used for evidential
purposes. However, the reader should be aware that the conclusions drawn
using different analytical methods will each have a different level of certainty.
Since similarity based on one method alone is usually not sufficient for evidential
purposes and in order to make the overall process more rigorous, the expert
group recommends the use of at least a second method where each method used
addresses a different set of target analytes. However, the decision whether or not
additional methods are required remains with the chemist on a case-by-case basis
and may also be dependent on national requirements. As a guiding principle, the
rigorousness of the method employed determines the strength of the evidence
produced.
In this context, it should also be understood that drug profiling is not a routine
analytical technique. Dedicated equipment and experienced chemists are
required and close cooperation between forensic laboratories and law enforcement
personnel is critical for effective use of results.
For further details on the background and operational value, as well as limitations,
of drug characterization and impurity profiling, the reader is referred to