Three laboratories present a harmonised system for the retrospective comparison of south west Asian heroin. It consists of an improved gas chromatographic (GC) profiling method and a computerised data retrieval. The investigations of the GC were necessary with a view to improve the reproducibility of the system. The necessity of a strict quality control is emphasized. The peaks of the GC profile were investigated for abundance, intensity, GC behaviour (reproducibility) and correlations; 16 of them were selected for describing the heroin profile in the database. The results from intra-lab profile comparisons are reported. The reproducibility of the analysis was good and the variation between the samples was large, thus, allowing conclusions with a high degree of certainty. The criteria of similarity were defined. The system is successfully running in all three labs. In connection with inter-laboratory comparison, the aspects of method harmonisation and standardisation are discussed. It appeared that the GC method is a very subtile one, urging for a strict standardisation between the three labs. Despite a long cooperation between three well-equipped and experienced labs, a more or less serious loss of reproducibility was noticed in the inter-lab results in comparison with the intra-lab results. The loss could for the greater part be attributed to the (limits of the) GC technique; a number of compounds, necessary for making the discrimination between samples, showed difficult chromatographic behaviour, leading to insufficient inter-lab reproducibility. Using the actual variables, improvements in performance can hardly be expected in the near future. The loss of reproducibilty implies that the number of false positive matches in a database search increases. This may strongly reduce the value of a relatively large, international database. The study shows that so far, the best option for international comparison is the analysis in a central laboratory. The idea of local determination at a large number of national labs and the use of a common database is not a realistic aim for this type of analysis.
[1]
H. Neumann,et al.
Profiling of illicit heroin samples by high-resolution capillary gas chromatography for forensic application
,
1982
.
[2]
Paul Geladi,et al.
Principal Component Analysis
,
1987,
Comprehensive Chemometrics.
[3]
L. Strömberg,et al.
Two-level classification of Leuckart amphetamine
,
1994
.
[4]
C S Jonson,et al.
Computer aided retrieval of common-batch members in Leuckart amphetamine profiling.
,
1993,
Journal of forensic sciences.
[5]
Helmut Neumann.
Comparison of heroin by capillary gas chromatography in Germany
,
1994
.
[6]
C.S.L. Jonson,et al.
Amphetamine profiling — improvements of data processing
,
1994
.
[7]
H. Huizer.
A contribution to comparison
,
1994
.
[8]
Manfred. Gloger,et al.
Analyse von heroinproben mit der Kapillargaschromatographie. Vergleich von Glaskapillartrennsäule und gepackter Säule
,
1983
.
[9]
D. A. Cooper,et al.
Illicit heroin manufacturing byproducts: capillary gas chromatographic determination and structural elucidation of narcotine- and norlaudanosine-related compounds.
,
1984,
Analytical chemistry.