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

28 Methods for impurity profiling of heroin and cocaine
Method B2: GC method, without derivatization*
Source: James Wong, Bureau of Drug Analysis Services, Health Canada, Western
Region Health Protection Branch, Burnaby, British Columbia, Canada.
Operating conditions:
Detector: FID
Column: DB-5 or equivalent (i.e., cross-linked 5% phenylmethylsilicone),
25 m x 0.32 mm x 0.52 µm
Carrier gas: Helium
Injection size: 2 µl; split, 25:1
Temperatures: Injector: 250° C
Detector: 310° C
Oven: 160° C, hold for 3 min, 3° C/min to 255° C, hold
for 1 min, 20° C/min to 295° C, isothermal for 10 min
Internal standard: None
Sample preparation: Dissolve 200-250 mg of heroin sample in 5 ml 0.5N sulphuric
acid, add 5 ml of glass-distilled CHCl 3 and thoroughly mix the two phases. Centrifuge
to separate phases and discard the aqueous phase. Add to the CHCl 3 solution 5 ml
0.5N sulphuric acid, mix thoroughly, centrifuge and discard the aqueous layer. Transfer
the CHCl 3 layer to a clean tube and evaporate to dryness at 45° C under a stream of
dry air of nitrogen. Reconstitute dried residue in 50 µl acetonitrile:toluene (1:9).**
Rationale for use: No derivatization*** and relatively simple sample preparation.
Will not detect sugars. Use of a moderately thick film column allows for high sample
loading.
Outcome: Sample comparisons for discrimination and evaluation of samples for caseto-case
evidential purposes (linkage determinations). Provides additional information
required to confirm links between samples, that is, the method should be used in conjunction
with a major component analysis.
*The Health Canada Laboratory uses this method, with identical parameters and sample preparation,
also for cocaine (method D3). However, wherever possible, and especially for forensic
comparative purposes, the use of dedicated instrumentation and optimized methodologies is
always preferred.
**The dried residue of the heroin acid and neutral extract may be crusty. Therefore, it may
be necessary to add 0.5 ml of 0.5N sulphuric acid and partition with the acetonitrile:toluene
mixture.
***See the subsection entitled “Hydrolysis of heroin” for possible problems related to the use
of methods that do not employ derivatization.