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

Methods for impurity profiling 23
Initial column conditioning: Flush the capillary with 0.1M NaOH, then with water,
then with CElixir reagent A (each for two minutes) and finish with run buffer for
four minutes.
Pre-injection column conditioning: Same procedure as initial.
External standards: Accurately weigh approximately 40 mg heroin HCl, 0.5 mg morphine
HCl, 0.5 mg O3MAM sulfamate, 0.5 mg codeine HCl, 0.5 mg papaverine HCl,
0.5 mg noscapine and 1.0 mg acetylcodeine HCl into a 100-ml volumetric flask and
dilute to volume with injection solvent. As a separate standard solution, accurately
weigh approximately 1.5 mg O6MAM into a 100-ml volumetric flask and dilute to
volume with injection solvent.
Sample preparation–heroin HCl: Accurately weigh an amount of sample approximately
equivalent to 20 mg of heroin HCl into a 50-ml volumetric flask and dilute to volume
with injection solvent. Assure dissolution before diluting to final volume.
Sonication for 15 minutes is recommended.
Sample preparation–heroin base: Accurately weigh an amount of sample approximately
equivalent to 10 mg of heroin HCl into a 50-ml volumetric flask and dilute
to volume with injection solvent. Samples containing both heroin base and heroin HCl
can be treated as hydrochloride samples if the base content is less than the hydrochloride
content. Assure dissolution before diluting to final volume. Sonication for 30 minutes
is recommended.
Reference chromatograms: see annex III, figure II and table 1.
Rationale for use: A rugged method providing good quantitative accuracy and precision
for heroin and all typical opium alkaloid impurities down to 0.2% relative to
heroin content. The minor alkaloids quantified are morphine, codeine, O3MAM,
O6MAM, papaverine and noscapine. Instrumentation cost is relatively modest and the
cost of consumables is due primarily to the use of the proprietary run buffers. However,
the use of the proprietary run buffers saves valuable operator time and significantly
enhances reproducibility. If followed faithfully this method provides for an on-column
heroin content that is in the middle of the quantification linearity range. Therefore, it
is not absolutely necessary for the analyst to obtain a “rough” quantification of the
heroin prior to analysis; however, this is highly recommended, as doing so assures
that consistent results are obtained in conjunction with detection and quantification of
the minor alkaloids at the 0.2% level relative to heroin content. The use of a photodiode
array (PDA) detector is also recommended as it allows for the confirmation of
peak identity and the facile detection of co-eluting compounds, that is, peak purity
assessments. For run buffer (a), co-elution issues occur for lidocaine and aminopyrene
with O3MAM and for dipyrone with O6MAM. The use of CZE run buffer (b)
in place of (a) will allow the determination of O3MAM and O6MAM in those situations.
Most weakly basic, acidic and neutral compounds are not detected and as a
result many co-elution issues are avoided. Effective mobilities are very reproducible,
but increases in absolute migration times are observed over time. This occurs as a