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

Methods for impurity profiling 39
Temperatures: Injector: 215° C
Detector: 325° C
Oven: 120° C, hold for 2 min, 6° C/min to 320° C, hold
for 5 min
Internal standard: None; normalize by peak area ratios for tropacocaine, norcocaine
and cis- and trans-cinnamoylcocaine relative to cocaine.
Sample preparation: Weigh the equivalent of 30 mg of cocaine base and dissolve in
2 ml of absolute ethanol.
Rationale for use: Not the most sensitive method, but a broad range of nitrogencontaining
compounds can be detected (by the same token, the majority of nitrogenfree
adulterants and diluents cannot be detected). Simple sample preparation (no
extraction or derivatization) enhances sample throughput.
Outcome: Sample comparisons for discrimination and evaluation of samples for caseto-case
evidential purposes. Additional information is required to confirm links
between samples or to assign source regions, that is, the method should be used as
one part within a broader analysis scheme.
2. Methods for the determination of trace components
The methods described below are used to substantiate the results obtained from
methods C1-C4. A potential limitation for the methods D1 and D2, presented
below, is that they are designed for the analysis of unadulterated samples.
However, methods D3 and D4 are not limited to unadulterated samples, but they
do not employ a derivatization step and, as a result, artefact production is a concern.
In addition, many of the by-products and decomposition products generated
during cocaine processing are not observed unless the sample is derivatized.
Hence, it is likely that no one of these methods will be suitable for every laboratory
and/or for every sample.
Some researchers have observed that the truxillines and the corresponding
truxillic/truxinic acids may not be ideal parameters for profiling purposes owing
to what is thought to be trans-isomerization and/or artefact formation.* However,
Moore and others [50-52] examined this issue in detail and found no evidence to
support this view. Rather, Moore and others describe a truxilline analysis method
and state that the method results are very reproducible and very useful for indicating
the country of origin. On the matter of benzoic acid, however, there seems
to be general agreement that it may not provide a very useful parameter for either
sample-to-sample comparison or origin determination.
*Personal communication from Olivier Guéniat, Police de sûreté, Neuchâtel, Switzerland, at the
Consultative Meeting held in Sydney, Australia, in 1999; see also Rivier [53].