Methods for impurity profiling of heroin and cocaine

22

Methods for impurity profiling of heroin and cocaine

1 ml 0.1N HCl, add solid sodium carbonate until basic, then add exactly 1 ml deriva-

tizing solution, vortex for about 30 seconds, centrifuge to separate phases. Aspirate

and discard top (aqueous) phase, bottom chloroform layer is subjected to GC-FID analy-

sis, where quantification and determination of the two pairs of ratios are examined. 

Rationale for use: Good resolution and discrimination power with a simple derivati-

zation scheme. The benzoyl derivative of O6MAM is completely resolved from acetyl-

codeine and derivatization also ensures that the O6MAM detected is not from the

degradation of heroin.

Outcome: Sample comparisons for discrimination and evaluation of samples for 

case-to-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.

Method A6:

Capillary electrophoresis (CE) methods

Source: I. S. Lurie and others, “Use of dynamically coated capillaries for the deter-

mination of heroin, basic impurities and adulterants with capillary electrophoresis”,

Journal of Chromatography A, vol. 1034, Nos. 1-2 (2004), pp. 227-235. (current DEA

Signature I)

Method A6.1:

Capillary zone electrophoresis (CZE)

Sample type: Major basic components: cut and uncut samples.

Operating conditions:

Agilent model HP

3D

CE

CZE:

Column maintained at 25° C with an applied potential of

30 kV

Detector:

UV diode array

Monitored wavelengths: 195 nm, 205 nm and 260 nm

Column:

64 cm x 50 µm fused silica (55.5 cm to detector window)*

Run buffers:

(a) 100-mM dimethyl-ß-cyclodextrin in CElixir reagent B

(pH 2.5)**

(b) 100-mM hydroxypropyl-ß-cyclodextrin in CElixir

reagent B (pH 2.5)

Injection solvent: 2:8 mixture of methanol and 3.75-mM monobasic sodium

phosphate buffer adjusted to pH 2.6 with phosphoric acid 

Injection:

500 mbar*s

*In the original reference, the fused silica tubing was obtained from Polymicro Technologies,

Phoenix, Arizona, United States. Columns can also be obtained from Agilent that are already

cut to length with the appropriately located detector window.

**CElirix reagents are proprietary products from MicroSolv Technology, Eatontown, New

Jersey, United States.

---

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 mor-

phine 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 vol-

ume 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 approxi-

mately 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 hydrochlo-

ride content. Assure dissolution before diluting to final volume. Sonication for 30 min-

utes is recommended.

Reference chromatograms: see annex III, figure II and table 1.

Rationale for use: A rugged method providing good quantitative accuracy and preci-

sion 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 photo-

diode 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 aminopy-

rene 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 situ-

ations. 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 

---