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48 Methods for impurity profiling of heroin and cocaine
magnitude of the analytical variance, in particular for the less abundant sample
components. For heroin and cocaine, one laboratory* has successfully applied
ratios for all major and minor components by expressing the ratios in terms of
the appropriate major analyte, morphine base or cocaine base. It is thought that
there is a significant advantage gained in employing this normalization calculation,
as it allows the ready assessment of sample hydrolysis and, in some instances,
the positive comparison of two samples that are identical except for the extent of
hydrolysis. For cocaine, this entails summing the sample quantities of ecgonine,
ecgonine methyl ester, benzoylecgonine and cocaine, while for morphine it is calculated
from the sum of morphine, O3MAM, O6MAM and heroin. These calculations
can be performed in several different manners where the exact method
employed for this calculation is much less important than is consistency in the
application. One example of such a calculation for morphine from a heroin sample
is as follows:
Heroin hydrochloride sample
Quantitation results: Heroin hydrochloride H2O = Hhcl
O6MAM hydrochloride 2-H2O = O6hcl
O3MAM hydrochloride 2-H2O = O3hcl
Morphine hydrochloride 3-H2O = Mhcl
(303.45/375.85 * Mhcl) + (303.45/399.87 * (O3hcl +O6hcl)) +
(303.45/423.89 * Hhcl) = total morphine base content expressed as the
monohydrate.
While this calculation would be a tedious operation if performed by hand, it is a
trivial calculation for the computer. Using the data derived from major component
analyses, some laboratories have used in-house database search and classification
algorithms, in some cases with commercial neural network programs. The
success of those heroin and cocaine algorithms in determining sample origin is
due largely to the fact that both algorithms rely on the normalization of all component
ratios to morphine or cocaine content, respectively.
There are several other data handling approaches in current use by various
laboratories that also rely on the use of ratios in order to normalize the data.
Typically the ratios for cis- and trans-cinnamoylcocaine to cocaine and O6MAM
and acetylcodeine to heroin are determined. Some will also include ratios for tropacocaine
and/or norcocaine to cocaine, and papaverine and noscapine to heroin.
Then when two samples are found with very similar ratios, they are considered
to be possible “matches” and are selected for additional comparative analyses,
usually for trace components.
The majority of those who perform these additional trace component analyses
for heroin use the procedure of Neumann and Gloger [56] or a modification
of that procedure. This procedure is a simple sulphuric acid extract whereby the
*Personal communication from Don Cooper, retired, Special Testing and Research Laboratory, Drug
Enforcement Administration, Dulles, Virginia, United States, 2005.