Methods for impurity profiling of heroin and cocaine



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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% phenylmethylsili-

cone), 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 sam-

ple loading. 

Outcome: Sample comparisons for discrimination and evaluation of samples for case-

to-case evidential purposes (linkage determinations). Provides additional information

required to confirm links between samples, that is, the method should be used in con-

junction with a major component analysis.

*The Health Canada Laboratory uses this method, with identical parameters and sample prepa-

ration, 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.



Methods for impurity profiling

29

Method B3:

GC method, with derivatization

Sources: A. C. Allen and others, “Illicit heroin manufacturing byproducts: capillary

gas chromatographic determination and structural elucidation of narcotine- and 

norlaudanosine-related compounds”, Analytical Chemistry, vol. 56, No. 14 (1984),

pp. 2940-2947; H. Neumann and M. Gloger, “Profiling of illicit heroin samples by high-

resolution capillary gas chromatography for forensic application”, Chromatographia,

vol. 16, 1982, pp. 261-264.

Method B3 is the analytical basis for the previously described method by Strömberg

and others [48] (method B1).



Operating conditions:

Detector:

FID

Column:


DB-1 or SE-54, 25 m x 0.25 mm x 0.25 µm 

Carrier gas:

Hydrogen at 50 cm/sec

Injection 

technique:

3 µl; split, 60:1

Make-up gas:

Nitrogen at 30 ml/min

Temperatures:

Injector: 300° C

Detector: 300° C

Oven: 200° C to 330° C at 4° C/min, hold for 4 min



Internal standard: n-Dotetracontane at 0.30 mg/ml in toluene or chloroform

Derivatization reagent: MSTFA (N-methyl-N-trimethylsilyltriflouroacetamide)

Sample preparation: Weigh out the sample in an amount equivalent to 15 mg of pure

heroin base. Add 5.0 ml of 0.5N sulphuric acid and dissolve the sample, add 5.0 ml

of toluene and mix thoroughly, then centrifuge to separate phases. Remove approxi-

mately 4 ml of the toluene layer and evaporate to dryness. Add to the residue 75 µl

of internal standard solution and 25 µl of MSTFA. Heat the solution at 75° C for

3 min.


(Modification by Olivier Guéniat)

Operating conditions: 

Detector:

FID at 45 ml/min hydrogen and 450 ml/min air

Column:


DB-1 or equivalent, 30 m x 0.25 mm x 0.25 µm

Carrier gas:

Helium at 1 ml/min

Injection size:

2 µl 

Temperatures:



Injector: 290° C

Detector: 320° C

Oven: 200° C to 320 °C at 4° C/min, hold for 4 min

Internal standard: Heneicosane at 0.10 mg/ml in methylene chloride



30

Methods for impurity profiling of heroin and cocaine

Sample preparation: Weigh out about 20 mg of the sample. Add 2.0 ml of 1M sul-

phuric acid, then add 2.0 ml of toluene and mix thoroughly. Remove 1 ml of the

toluene layer and evaporate to dryness under a nitrogen stream. Add to the residue

75 µl of methylene chloride and 25 µl of MSTFA. Heat the solution at 75° C for

30 min.

Rationale for use: Several modifications of the above methods are in use worldwide.

Provides synthesis and processing information and alkaloidal information that can 

be linked back to the original opium poppy. Typically the sample amount can be

increased two to three times in order to gain the sensitivity necessary for highly refined

heroin samples.

Outcome: Indication of general source region (South-East Asia, South-West Asia,

Mexico, South America). Sample comparisons for discrimination and evaluation of

samples for case-to-case evidential purposes (linkage determinations). Provides addi-

tional information required to confirm links between samples, that is, the method

should be used in conjunction with a major component analysis.

Method B4:

GC/MS method, with derivatization

Sources: Jana Skopec, Australian Government Analytical Laboratories, Pymble, New

South Wales, Australia; R. B. Myors and others, “Investigation of heroin profiling

using trace organic impurities”, The Analyst, vol. 126. No. 5 (2001), pp. 679-689.

Operating conditions:

Detector:

Mass spectrometer, EI, 40-600 amu, 1 sec scan cycle 

(or SIM mode)*

Column:

DB-5 or equivalent, 30 m x 0.25 mm x 0.25 µm



Carrier gas:

Helium at 41 cm/sec, constant flow

Injection 

technique:

1 µl splitless

Temperatures:

Injector: 260° C

Detector: 280° C (MS transfer line); 230° C (MS source)

Oven: 100° C for 1 min, to 230° C at 6° C/min, to 280° C

at 3° C/min, to 320° C at 6° C/min, hold for 4 min



Internal standard: Benzopinacolone at 1.0 mg/ml in methylene chloride

Derivatization solution: Dilute 1 ml of BSTFA (N,O-bis-(trimethylsilyl)triflouro-

acetamide) containing 1% TMCS (trimethylchlorosilane) to 2 ml with dichloromethane.**

*Personal communication from Jana Skopec, 2005.

**Derivatization solutions can be stored for a maximum of 24 hours.




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