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

Methods for impurity profiling 43
Rationale for use: No derivatization and relatively simple sample preparation. Good
retrospective data searches via comparison of the ratios of cis-cinnamoylcocaine and
trans-cinnamoylcocaine to cocaine.
Outcome: Sample comparisons for discrimination and evaluation of samples for caseto-case
evidential purposes (linkage determinations). Should be used to substantiate
results of the methods used for major components.
Method D4: GC or GC/MS method, without derivatization
Source: M. LeBelle and others, “Comparison of illicit cocaine by determination of minor
components”, Journal of Forensic Sciences, vol. 36, No. 4 (1991), pp. 1102-1120.
Method D4.1: GC/MS method, without derivatization
Operating conditions (GC/MS method):
Detector: Finnigan Mat Model 800 Ion Trap Detector, electron
impact mode 40 to 500 amu, 1 sec scan cycle
Column: DB-5 or equivalent, 15 m x 0.25 mm x 0.25 µm
Carrier gas: Helium at 55 cm/sec at 160° C oven temperature
Injection
technique: 1 µl; split 25:1
Temperatures: Injector: 275° C
Oven: 160° C for 3 min, 3° C/min to 255° C for 1 min,
20° C/min to 295° C, final hold for 1 min
Sample preparation: To a 400 mg uncut sample add 5 ml of 0.5 M sulphuric acid
and 5 ml of toluene and mix thoroughly. Centrifuge to separate phases, aspirate as
much toluene as possible, add 5 ml of 0.5 M H 2 SO 4 , mix, centrifuge and aspirate the
toluene layer. Combine the toluene extracts and evaporate under a stream of nitrogen at
40° C. Immediately dissolve the residue in 50 µl of ethyl acetate. Inject, in duplicate.*
Method D4.2: GC method, without derivatization
Modification of method D4.1
Operating conditions (GC method):
Detector: FID, at 30 ml/min hydrogen and 400 ml/min air
Column: DB-5 or equivalent, 15 m x 0.25 mm x 0.25 µm
Carrier gas: Helium at 40 cm/sec at 160° C oven temperature;
head pressure 85 kPa
*If a sample cannot be analysed immediately, evaporate it almost to dryness and store the
resulting sample in a refrigerator (5° C) for future analysis.