Parameters for determining the origin of illicit heroin samples

Sections

ABSTRACT
Introduction
Claudestine separation of morphine from opium
Clandestine heroin manufacturing
Classification criteria
Parameters
Materials and methods
Assay of illicit heroin sample
Results and discussion
Concluding remarks
Acknowledgment

Details

Author: K. NARAYANASWAMI
Pages: 49 to 62
Creation Date: 1985/01/01

Parameters for determining the origin of illicit heroin samples

K. NARAYANASWAMI
Department of Science and Technology, New Delhi, India

ABSTRACT

A method has been evolved for assigning the source of supply or origin of illicit heroin samples. The content of morphine, codeine and acetyl products and the ratios of morphine to codeine and heroin to acetylcodeine obtained from opium samples of known origin as well as the content of heroin (diacetylmorphine) and acetylcodeine and their ratios in illicit heroin samples that have been found to belong to the same source of supply as the known opium samples are used as the basic criteria for a comparison to determine the origin of illicit heroin samples. Because the content of alkaloids in opium and heroin samples varies considerably, the number of opium and illicit heroin samples of known origin analysed should be sufficient to determine a representative composition of alkaloids in such samples for a given geographical area and period of production.

It was observed that the theoretical ratio of heroin to acetylcodeine increases two-fold at each stage of the chemical conversion in the series opium-morphine-heroin. The ratios of heroin to acetylcodeine obtained from opium samples of known origin showed significant variation, which enabled the author to make distinct composition profiles of the alkaloids for each geographical area studied. Such profiles made it possible to compare heroin samples of known origin with illicit heroin samples of unknown origin and to determine the geographical area from which the latter originated. This method can also be applied in determining the origin of illicit morphine samples.

Introduction

The sharp increase in the abuse of heroin, one of the most potent narcotics, has prompted the international community to impose strict control over the trade and use of this drug. It is therefore very useful to know whether an illicit heroin sample comes from the same batch as heroin whose origin is already known in order to determine the source of illicit heroin supply and thus to discover heroin trafficking routes by following a particular batch of heroin during its movement and distribution.

Heroin (diacetylmorphine) is derived from morphine by acetylation. Morphine is the major alkaloid present in the opium poppy, a plant of the species Papaver Somniferum L.

Claudestine separation of morphine from opium

Generally 1 kg of opium is mixed with 200 g of lime and dissolved in 2 l of water in a container. An amount of 250 g of ammonium chloride is added to this mixture. The content is stirred with 500 ml of alcohol and 500 ml of ether. The entire solution is then filtered through a fine cloth. The filtered material becomes the morphine base, which is then mixed with a certain quantity of sulfuric acid to dissolve it; 250 g of charcoal dust is added to this solution and diluted with 4 l of water. The mixture is heated and boiled for about half an hour. The content is filtered and ammonium hydroxide is added to the filtrate. The precipitate formed is filtered and the moisture content in the base is removed by air drying. The resulting hard morphine base is rubbed on a hard surface to produce granules or powder. The morphine thus obtained has a brownish colour.

Clandestine heroin manufacturing

One kg of opium is treated with lime and dissolved in a plastic bucket filled about three-quarters full with water to isolate the insoluble matter. The content is filtered through a coarse cloth, and 250 g of ammonium chloride is added to 1 kg of the filtrate in a plastic container and mixed. The content is allowed to stand for a short time and is then passed through a fine cloth. The precipitate is washed with water. The resulting product is crude morphine, which is then dissolved in hydrochloric acid or sulphuric acid in a 5-1 flask. Animal charcoal is added to this solution, and the content is heated over a stove and filtered hot through a filter paper. Ammonium hydroxide is added to the filtrate, which precipitates the morphine. The content is filtered again, and the morphine base is dried.

The dry morphine is submerged in a flask to which acetic anhydride has been added. Then the contents are heated for five hours at a constant temperature. After cooling, the contents are transferred to a plastic bucket, and sodium carbonate powder is added to separate the mass. The mass, which forms heroin base, is faltered and washed with water.

The crude heroin is mixed with citric acid, charcoal and water in a flask and then heated and filtered through a filter paper. Sodium carbonate is added to the cold filtrate to precipitate the heroin. The mass is then passed through a fine cloth to separate the heroin base. The base is dissolved in acetone in a container, and hydrochloric acid is added until the solution changes colour with blue litmus. The content is dried in air; in case of difficulty in removing the moisture, ether is added. The granular heroin hydrochloride is formed and ground with a bottle to prepare the powder base.

The type of heroin known as No. 3 or Asian heroin is light grey-brown in colour and contains almost 40 per cent heroin and 5 to 6 per cent acetylcodeine.

Classification criteria

The amounts of different alkaloids in the opium poppy can vary greatly, depending on such factors as the climate, the altitude, the fertility of the soil, the amount of available moisture, the age of the plant, the time of lancing and the variety of Papaver Somniferum. An attempt was made in an earlier study [1] to locate the geographical origin of the opium samples on the basis of the content of alkaloids in such samples.

The impurities and additives found in samples of heroin sold on the streets have been studied using high-performance liquid chromatography (HPLC) [2, 3] , gas-liquid chromatography (GLC) [4] and infra-red spectrometry (IRS) [5] . An attempt was also made to classify seized heroin samples into groups or batches based on the content of heroin and other substances contained in a sample [2] . It is, however, difficult to connect the relevant batch data of clandestine heroin samples to the source of heroin supply [6] .

The criteria that are useful in determining the origin of samples of seized heroin should be based on the compounds carried over from the opium raw material and from the acetylation process [7] . The identification of diluents and impurities that could provide evidence of similarities between seized samples of heroin is of little value in determining the origin of heroin, whereas colouring agents and adulterants could be indicative of the origin of heroin [7] .

In order to determine the origin of an illicit heroin sample it is necessary to draw up its profile, which includes the absolute content of the major alkaloids and their respective ratios. The absolute content of heroin and acetylcodeine in a sample may vary depending on the manufacturing process adopted and on the formulation of the product. Since clandestine heroin is usually obtained from opium using a crude manufacturing process, the final product is not refined and therefore contains compounds carried over from opium and from the acetylation process. It is assumed that the ratio of heroin to acetylcodeine in the clandestine manufacturing of heroin remains unaltered in the end-product. However, the absolute content of heroin and acetylcodeine is likely to vary from one sample to another, but this variation should in no way vitiate conclusions that can be drawn on the basis of comparisons between ratios of these alkaloids.

Parameters

The parameters of the present study are based on the content of morphine and codeine and the ratio between them, as well as their respective acetyl products (heroin and acetylcodeine) and the ratio between them. These data can be obtained from opium samples known to be from a specific geographical area and a given period of production. The parameters also include the content of alkaloids (heroin and acetylcodeine and the ratio between them) in illicit heroin samples that are known to be from the same source of supply as authenticated opium samples from a given geographical area and period of production. A comparison of the alkaloid composition profile of the authenticated opium samples and illicit heroin samples derived from the same source of supply with the alkaloid composition profile of illicit heroin samples of unknown origin can lead to the identification of the origin of the heroin.

Materials and methods

In earlier studies [1] samples of opium from different countries and from various regions of India were evaluated for their morphine and codeine content using GLC and other methods [8, 9] . The results obtained and the data provided by the Division of Narcotic Drugs enabled the author to determine the alkaloid content of opium samples from various geographical areas and to obtain data on morphine and codeine and the ratio between them as well as on heroin and acetylcodeine and the ratio between them. As the number of opium samples from different geographical areas was not sufficient to permit statistically significant inference, published data on the analysis of authenticated opium samples formed an important component in this study [10] . Since authenticated samples were difficult to obtain, it was possible to determine that illicit morphine and heroin samples came from the same source as opium of known origin in only two geographical areas. Fourteen illicit heroin samples seized from 1977 to 1983 at New Delhi and four illicit morphine samples seized in 1978 were analysed using GLC. In a reference opium sample obtained from Ghazipur, India, morphine was precipitated by the British Pharmacopoeia (BP) method [11] and quantified by GLC as its silyl ether.

The reference compounds in opium, morphine and codeine were obtained from opium that belonged to the Alkaloid Works, Ghazipur. The standard diacetylmorphine, monoacetylmorphine and acetylcodeine were synthesized using standard procedures [12] .

Assay of illicit heroin sample

GLC analysis was performed in a Perkin-Elmer gas chromatograph model F 11, equipped with a hydrogen flame ionization detector. The glass columns (2m 3mm ID) were packed with 3.8 percent UCW-98 on 100-120 mesh. The GLC unit was operated isothermally at 225°C with a nitrogen flow rate of 65m/min and a head pressure of 2.1kg/cm ², with hydrogen at 1.25kg/cm ² and air at 1.5kg/cm ².The chart speed was kept at 1cm/min. Attenuation was set at 2 x 10 ²; 0.2 µl of the solution with a concentration of 11mg per 1 ml of chloroform was used for GLC study. The typical chromatogram obtained from an illicit heroin sample is shown in figure I.

Heroin, acetylcodeine, monoacetylmorphine, caffeine and strychnine were used as reference standards, with codeine as an internal standard. First, each sample was screened for the presence of codeine, and whenever it was detected the composition of the sample was determined in the absence of the internal standard. The quantities of heroin, acetylcodeine and monoacetyl-morphine in the sample were obtained by acetylation. The standard error for a typical sample was less than 0.5 per cent.

Results and discussion

Lim and Chow [4] observed in Singapore that the ratio of heroin to acetylcodeine in illicit heroin samples was approximately the same as the ratio of morphine to codeine found in illicit morphine samples. It was inferred that those morphine samples were from morphine that was used as the starting material in the manufacture of the illicit heroin samples. Morphine that is fairly free of other alkaloids may be obtained from opium by using the BP method [11] . Other techniques that are used in clandestine production result in morphine that has a considerable amount of codeine in it. Morphine obtained using the BP or the other methods can be used as the starting material for manufacturing heroin. It has been observed that most of the heroin samples encountered as street drugs were produced under clandestine manufacturing conditions and had a considerable amount of acetylcodeine carried from the acetylation process.

An assay of an Indian raw opium sample using the BP method showed that it contained 11.1 per cent morphine. However, GLC analysis of the precipitated morphine obtained by the BP method showed that it was a mixture of 95 per cent morphine and 4.9 per cent codeine. Rakshit [13] also observed that morphine obtained using the BP method contained 1 to 3 per cent. codeine, depending on the type of opium. Hence, the precipitated morphine in the Indian opium sample would be an admixture of 10.55 per cent morphine and 0.54 per cent codeine, with a morphine to codeine ratio of 19.54 : 1 . The theoretical conversion of these values to heroin and acetyl-codeine gives respectively an equivalent heroin to acetylcodeine ratio of 22.03 : 1 . These results, which are obtained using the BP method, are markedly different from the results obtained under clandestine conditions in which crude morphine is invariably used for the manufacture of heroin.

Table 1 shows the determining features of illicit heroin obtained from known samples of opium from various countries and Hong Kong. The laboratory analyses were performed using the GLC and other methods [8, 9] . The data on percentages of morphine, codeine, heroin and acetylcodeine obtained from known opium samples as well as the corresponding ratios of morphine to codeine and theoretical and experimental ratios of heroin to acetylcodeine permit comparisons to be made between these samples and illicit heroin samples the origin of which is to be determined. The average theoretical ratio of heroin to acetylcodeine obtained from opium samples in India is 3.24: 1, which is approximately seven times less than the value obtained using the BP method. The theoretical ratios, based on an analysis of raw opium samples from a given country or territory, are presented in average values in order to offset the fluctuations in composition owing to climatic conditions and other possible intervening factors. The theoretical ratios of heroin to acetylcodeine content in known samples of opium from various countries and territories vary from 1.68 : 1 to 11.01 : 1. In contrast, the experimental ratios of heroin to acetylcodeine, based on the analysis of the same opium samples from the same countries and territories, vary from 6.38 : 1 to 31.80 : 1 (figure II).

Table 1

Features of illicit heroin obtained from known opium samples

Sample	Morphine (M) (%)	Codeine (C) (%)	Morphine/codeine ratio (M/C)	Heroin (H) (%)	Acetylcodeine (AC) (%)	Heroin/acetyl-codeine ratio (H/AC)a	Heroin/acetyl-codeine ratio (H/AC)b
			Afghanistan
UNE 544	11.43	3.28	3.48	14.82	3.92	3.78
UNE 545	12.75	2.91	4.38	16.5	3.47	4.75
UNE 546	16.38	2.19	7.47	21.2	2.61	8.12
					Average	5.55	20.9
			China
UN 37B	10.13	6.47	1.56	13.1	7.7	1.68	6.38

			China (Manchuria)
63423	8.66	4.39	1.97	11.25	5.30	2.12	8.00

			Hong Kong (Pukto)
63431	10.55	3.67	2.87	13.71	4.43	3.09
63424	11.90	3.78	3.15	15.3	4.49	3.40
52844	16.65	4.22	3.94	21.4	5.01	4.27
52846	6.97	3.40	2.05	8.99	4.04	2.22
					Average	3.25	12.12

			India
RCL 219 c	14.63	4.82	3.03	17.80	5.45	3.27
RCL 247 c	14.81	3.96	3.74	18.02	4.46	4.04
RCL 250 c	15.00	5.41	2.77	18.25	6.12	2.98
RCL 262 c	16.20	6.43	2.52	19.71	7.27	2.71
Ghazipur d	13.88	4.31	3.22	16.89	4.87	3.47
					Average	3.25	12.31

			Iran (Islamic Republic of)
UNE 511	19.46	4.07	4.78	25.2	4.85	5.19
UNE 513	16.21	3.18	5.10	21.0	3.79	5.54
UNE 514	15.02	3.83	3.92	19.45	4.57	4.26
UNE 515	16.72	4.65	3.59	21.7	5.55	3.91
UNE 516	14.71	4.46	3.30	19.1	5.32	3.59
UNE 517	12.81	4.15	3.09	16.6	4.95	3.35
UN-M5	6.60	2.76	2.39	8.58	3.3	2.6
					Average	4.06	15.4

			Japan
527	14.10	2.35	6.00	18.31	2.80	6.54
529	15.11	3.29	4.59	19.13	3.92	4.88
530	15.82	3.88	4.08	20.55	4.63	4.44
531	14.04	3.53	3.98	18.24	4.21	4.33
UN-M1	10.75	3.78	2.84	13.9	4.5	3.09
63426	17.85	2.32	7.69	21.72	2.62	8.29
					Average	5.26	20.31
26A	12.96	2.89	4.48	16.7	3.43	4.87
27A	12.56	1.86	6.75	20.9	2.21	9.46
27B	13.45	2.41	5.58	17.3	2.86	6.05
					Average	6.79	25.69

			Mexico
UN 579	9.33	1.64	5.69	12.04	1.95	6.17	23.37

			Pakistan
UN 269	10.28	2.53	4.06	13.3	3.02	4.40
UN 270	8.38	3.24	2.59	10.82	3.86	2.80
UN 194	12.2	3.4	3.59	15.85	4.1	3.86
					Average	3.83	14.5

			Singapore
63425	13.68	3.72	3.68	17.6	4.42	3.98	15.12

		Turkey
UN 40	14.02	2.05	6.84	17.06	2.32	7.35
UN-M3	13.09	1.29	10.15	17.05	1.535	11.11
UN 2A	13.16	1.87	7.04	17.03	2.23	7.64
UN 148A	14.96	5.39	2.77	19.43	6.40	3.04
					Average	7.28	27.5

		Viet Nam
28	12.10	1.37	8.83	15.6	1.63	9.57
280	13.39	1.97	6.80	17.2	2.34	7.35
28G	15.54	1.98	7.85	20.0	2.35	8.5
					Average	8.47	31.8

^aTheoretical ratio.

^bExperimental ratio.

^{c C}omposite sample from 1976.

^{d .}Composite sample from 1984

Figure II

Correlation of illicit heroin samples with known samples of opium from various countries

Table 2 shows the average content of morphine, codeine, heroin and acetylcodeine and the ratios of morphine to codeine and heroin to acetylcodeine with the respective conversion factor in authenticated opium samples and in illicit morphine and heroin samples from Hong Kong and Pakistan. The history of the analysed morphine and heroin samples was established, linking them to the same sources of supply as those for opium samples in either Hong Kong or Pakistan.

Table 2 shows that the ratios of heroin to acetylcodeine increase approximately two-fold at each stage of conversion in the series opium- morphine-heroin. A correspondence of 1 : 3.8 exists between the morphine to codeine ratio in opium and their respective acetylated products in clandestine heroin samples. In light of this observation it is possible to establish values for the ratio of heroin to acetylcodeine for heroin using the conversion factor 3.8 for opium samples of known geographical origin- The theoretical ratios of heroin to acetylcodeine for opium samples of known origin and the experimental ratios of heroin to acetylcodeine for heroin samples from various countries and areas are given in table 1. The results show significant variations in heroin to acetylcodeine ratios of samples from different geographical areas. These variations must be considered in correlating data on illicit heroin samples of unknown origin and data on known samples in order to assign the origin of heroin. This hypothesis was tested by using the clandestine heroin sample that originated in Hong Kong. The ratio of heroin to acetylcodeine in this sample when converted into a morphine to codeine ratio was compatible with the established morphine to codeine ratio of known opium samples from Pukto, Hong Kong (see table 1).

The correlation of data on opium samples of known sources with analytical data on illicit heroin seized in various parts of the world provided useful information about international trafficking patterns of heroin. The examination of the results of the analysis of illicit heroin samples seized in different countries (table 3) revealed the presence of samples from China and Hong Kong, for example, in different parts of the world. The study showed the prevalence of illicit heroin samples originating from Afghanistan, the Islamic Republic of Iran and Pakistan in India. Heroin samples from China, India and Pakistan were found in the Netherlands, and heroin samples from Hong Kong and the Islamic Republic of Iran were found in the Federal Republic of Germany. Heroin samples found in the United States of America showed that the heroin traffic originated from the Islamic Republic of Iran, Mexico, Pakistan and Turkey. The findings corroborated the reports of Governments to the United Nations on heroin trafficking trends for 1976 and 1977 [14]

Table 2

Analyses of autheuticated opium samples and illicit morphine and heroin samples from the same sources as opium samples in Hong Kong and Pakistan

^a Experimental ratio.

^b Theoretical ratio. .

In table 4, the results of the analysis of four illicit morphine samples are shown.

Table 3

Analyses and origin of illicit heroin samples seized in various countries

Sample	Heroin (H) (%)	Acetylcodeine (AC) (%)	Heroin/acetylcodeine ratio (H/AC)	Country or area of origin
		Germany, Federal Republic of
Abb 3 (Granular heroin)	72.5	3.9	18.6	Iran (Islamic Republic of)
Abb 4 (Hong Kong rocks)	44.3	4.4	11.05	Hong Kong
		India (New Delhi)
77-3106	35.5	2.42	14.7	Pakistan
77-3107	22.4	0.85	26.4	Lao People&rsquos Democratic Republic
81-3906	26.3	1.20	21.9	Afghanistan
81-3908	42.6	2.12	20.1	Afghanistan
81-RC8	30.8	2.36	13.1	lndia
82-1014	51.5	8.60	5.95	China
82-1015	83.5	10.30	8.1	China (Manchuria)
82-1016	48.2	4.90	9.8	Hong Kong
82-1017	69.5	8.95	7.76	China (Manchuria)
83-1266	71.5	4.90	14.6	Pakistan
83-1290 (A1)	20.6	1.42	14.5	Pakistan
83-1290 (B1)	31.5	1.85 17.02	Iran	(Islamic Republic of)
83-1290 (G)	17.3	0.96	18.0	Iran (Islamic Republic of)
		Netherlands
76-23891	47.3	7.9	5.99	China
76-23895	48.2	7.8	6.18	China
76-24047	35.9	2.6	13.81	Pakistan
76-24049	34.9	5.8	6.02	China
76-24050	35.5	5.9	6.02	China
76-24052	35.9	2.5	14.36	Pakistan
76-24141(1)	37.1	2.9	12.79	India
76-24141(2)	37.2	2.6	14.30	Pakistan
76-24307(1)	34.8	6.3	5.52	-
76-24307(2)	31.7	3.5	9.1	-
76-24307(3)	34.6	6.3	5.5	-
76-24562	40.4	6.6	6.12	China
76-24575(4)	43.3	6.1	71.0	-
76-24575(5)	43.8	6.2	7.06	-
		Singapore
1	42.6	4.7	9.1	-
2	38.0	6.9	5.5	-
3	48.1	4.3	11.2	Hong Kong
4	56.9	6.6	8.6	China (Manchuria)
5	42.0	5.0	8.4	China (Manchuria)
6	42.0	4.0	10.5	Hong Kong
7	42.4	5.0	8.5	China (Manchuria)
8	27.2	3.7	7.4	-
9	78.0	7.3	10.7	Hong Kong
10	83.3	10.2	8.2	China (Manchuria)
11	80.5	7.1	11.3	Hong Kong
12	46.2	3.9	11.8	Hong Kong
		United States of America
T-1771	30.2	0.9	33.5	Viet Nam
T-1772	32.6	0.975	33.4	-
T-1775	94.9	2.98	31.9	Turkey
T-1777	36.0	1.135	31.72	Turkey
T-1833	19.3	0.69	27.7	Turkey
4A	91.9	6.18	14.87	Pakistan
4B	91.9	5.59	16.4	Iran (Islamic Republic of)
3	81.44	11.32	7.2	-
2	91.4	7.95	11.5	Hong Kong
1	94.0	5.72	16.4	Iran (Islamic Republic of)
		United States (Miami)
1a	-	-	11.25	Hong Kong
2b	-	-	21.3	Afghanistan
3b	-	-	23.6	Mexico
4b	-	-	16.8	Iran (Islamic Republic of)

Table 4

Analyses of four illicit morphine samples

Sample	Morphine (M) (%)	Codeine (C) (%)	Morphine/codeine ratio (M/C)	Heroin (H) (%)	Acetylcodeine (AC) (%)	Heroin/acetyl-codeine ratio (H/AC)a	Country or area of origin
78-121 a	65.4	11.37	5.75	85	13.6	6.25	Hong Kong
78-4224(3)	73.5	8.85	8.3	95	10.28	9.24	-
M (A)	38	5.45	6.97	48.5	6.5	7.46	Pakistan
78-1265	19.2	6.9	2.78	24.8	8.25	3.01	-

^aTheoretical ratio.

Concluding remarks

The method described above is intended to establish the source of illicit heroin samples based on the absolute content of alkaloid compounds carried over from opium raw material, the characteristics of morphine isolated at the intermediate stage and the characteristics of compounds produced in the end during acetylation. The morphine to codeine and heroin to acetylcodeine ratios permit valuable comparisons of illicit samples with known samples.

Morphine, obtained at the intermediate stage, is also frequently encountered in illicit traffic, but no efforts have so far been made to determine its origin. The technique employed for the determination of illicit heroin samples could also be applied for identifying sources of clandestine morphine in illicit traffic using the factor 1.95 for setting up the ratio of morphine to codeine in opium samples known to be from different geographical areas.

Analytical data and information on illicit heroin or morphine samples with established histories and a chemical composition profile obtained from opium samples known to be from given geographical areas and produced in successive years would clearly set the scenario for determining the origin of illicit heroin or morphine. The number of analysed opium samples and illicit heroin or morphine samples of known origin must be sufficient to provide statistical representation for a given geographical area and a given period of production.

Acknowledgment

The author wishes to thank the Division of Narcotic Drugs of the United Nations Secretariat for supplying the analytical information on a few autheuticated opium samples. The technical assistance of Shri N. K. Prasad and D. Dua from the Central Forensic Science Laboratory, New Delhi, is also acknowledged with thanks.

References

⁰⁰¹

K. Narayanaswami, H.C. Golani and R.D. Dua, "Assay of major and minor constituents of opium samples and studies of their origin", Forensic Science, vol. 14, No.3 (1979), pp. 181-191.

⁰⁰²

H. Huizer, H. Logtenberg and A. J. Steenstra, "Heroin in the Netherlands", Bulletin on Narcotics (United Nations publication), vol. 29, No. 4 (1977), pp. 65-74.

⁰⁰³

J. L. Love and L. K. Pannell, "A high performance liquid chromatographic method for analysis of illicit heroin", Journal of Forensic Sciences, vol. 25, No. 2 (1980), pp. 320-326.

⁰⁰⁴

H.Y. Lim and S.T.Chow, "Heroin abuse and a gas chromatographic method for determining illicit heroin samples in Singapore", Journal of Forensic Sciences, vol. 23, No. 2 (1978), pp. 319-328.

⁰⁰⁵

J. Reuland and W. A. Trinler, "An unequivocal determination of heroin in simulated street drugs by a combination of high-performance liquid chromatography and infra-red spectrophotometry using micro-sampling techniques", Forensic Science, vol. 11 (1978), pp. 195-200.

⁰⁰⁶

"Report of an expert group meeting on the feasibility of using chemical characteristics for identifying sources of heroin and for tracking its movement in the illicit traffic, Hong Kong, October 1977" (MNAR/8/1977/UNFDAC).

⁰⁰⁷

"Review and implementation of the programme of strategy and policies for drug control" (E/CN.7/1983/2/Add.4).

⁰⁰⁸

"The assay, characteristics, composition and origin of opium-analysis of authenticated samples" (ST/SOA/SER.K/35 and Corr.1).

⁰⁰⁹

"Methods of determining the origin of opium by chemical and physical means" (E/CN.7/202).

⁰¹⁰

"The assay, characteristics, composition and origin of opium" (ST/SOA/SER.K/38; ST/SOA/SER.K/53; ST/SOA/SER.K/69).

⁰¹¹

British Pharmacopoeia (London, H.M. Stationery Office, 1973), p. 331.

⁰¹²

W. P. Butler, "Methods of analysis", Internal Revenue Service publication, No. 341 (Washington, D.C., 1967), pp. 49 and 60.

⁰¹³

J. N. Rakshit, Analyst, 56 (1931), p. 711.

⁰¹⁴

Official Records of the Economic and Social Council, 1978, Supplement No.5 (E/1978/35), pp. 6-19.