Journal of Analytical and Applied Pyrolysis, 17 (1989) 83-89
Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands

DETERMINA
TION OF ALKALOIDAL NARCOTICS
DETERMINATIONTOGRAPHY
BY PYROLYSIS-GAS CHROMAPYROLYSIS-GAS
CHROMATOGRAPHYTOSHIYUKI MITSUI * and MINEMASA HIDA
Criminal Science Laboratory, Aichi Prefecture, Sannomaru, Naka-ku, Nagoya-shi (Japan)

YOSHIKAZU FUJIMURA
Department of Industrial Chemistry, Faculty of Engineering, University of Chubu, Matsumotocho, Kasugai-shi, Aichi (Japan)(Received May 29th, 1989; accepted July 6th, 1989)
ABSTRACTThe alkaloidal narcotics in urine are extracted with dichloromethane and heated toevaporate the solvent. The salts of alkaloidal narcotics are pyrolyzed and analyzed by gas
chromatography. By this method, the alkaloidal narcotics can be determined with highsensitivity and with good reproducibility.
Alkaloidal narcotics; gas chromatography; pyrolysis.

INTRODUCTION
Alkaloidal narcotics marketed as painkilling drugs have been analyzed bygas chromatography (GC) [1] or gas chromatography/mass spectrometry(GC/MS) [2], absorption spectrometry [3] in aqueous solution and high-performance liquid chromatography (HPLC) [4] in aqueous or organic solvents.
When alkaloidal narcotics in human urine are analyzed, they have to beextracted by organic solvents under alkaline conditions. The salts of alkaloidal narcotics have high boiling points, and cannot be analyzed by GC.
In this paper, the alkaloidal narcotics are pyrolyzed as alkaloid salts andthe pyrolyzed compounds are analyzed by GC. We have previously reported
a method of pyrolysis [5-8] which is characterized by adding metal andinorganic compound to the sample in the pyrolysis foil: by this method,organic compounds were analyzed with high sensitivity and good reproducibility. We have pyrolyzed the alkaloidal narcotics by the same method.

EXPERIMENTAL
The pyrolysis foil with a Curie point of 590°C was used to pyrolyze thealkaloidal narcotics. A mixture of iron powder and sodium carbonate
anhydride (30 mg: 4:1 w/w) was first put into the pyrolysis foil. An
aqueous solution of the sample was placed in the pyrolysis foil by using a50ì l microsyringe. The foil was dried on a hot plate for 5 min at about
1 0 0 ° C t o e v a p o r a t e t h e w a t e r. A f t e r c o o l i n g t o r o o m t e m p e r a t u r e , t h epyrolysis foil was folded up and inserted into the Curie-point pyrolyzer. Thepyrolysis time was 4 s. The pyrolysis products were separated by GC and theproduct of 3.7 minutes’ retention time was determined by measurement of
the peak area. The pyrolysis products were identified by GC/MS. Thepyrolysis product of morphine hydrochloride, codeine phosphate and dihydrocodeine phosphate is 3,4-dimethyl-l,2-dihydroxybenzene, which was determined. The operating conditions of pyrolysis and GC are shown in Table
1 and the pyrogram of morphine hydrochloride is shown in Fig. 1.
Selection of suitable metals and inorganic compounds
The metal powder, which is added to conduct heat from the pyrolysis foil
to alkaloidal narcotics, such as aluminium, iron, chromium, zinc, manganese,nickel or copper, was put into the pyrolysis foil together with the sample andpyrolyzed. Iron powder showed the highest sensitivity of all the metalp o w d e r s ( Ta b l e 2 ) .
T h e e ff e c t o f i n o rg a n i c c o m p o u n d s , w h i c h a r e a d d e d t o c o n t r o l t h epyrolysis temperature, such as sodium carbonate, potassium iodide or ammonium sulphate, added together with the iron powder to raise its sensitivity, were studied at 590°C. The results are shown in Fig. 2. The best mixture
ratio of iron and sodium carbonate was between 5 : 1 and 2 : 1.
TABLE 1
Operating conditions of the instrument
Pyrolyzer

Japan Analytical Industry JHP-2

Oven temperature

150°C

Pipe temperature

200°C

Pyrolysis temperature

670°C ; 4s

Gas chromatograph

Hitachi 163

Column

10% PEG 20M Chromosorb W (AW-DMCS)
2mX3mmI.D.

Column temperature

50°C

Injection temperature

180°C

Carrier gas

NitrogenDetector

Flame ionization detector

TABLE 2
Effect of metal (20 mg) on the pyrolysis of 32 /ìg morphine hydrochloride
MetalPeak area(X104)
AI
3.52
Fe19.37
Cr17.43
Zn4.36
Mn
7.64
Ni
0.43
Cu
1.01
Effect of amount of added mixture
The amount of the mixture added to the pyrolysis foil was varied from 6to 50 mg. 50 mg was the maximum weight suitable for the pyrolysis foil, theoptimal sensitivity was obtained between 20 and 50 mg (Fig. 3).

Effect of pyrolysis temperature
T h e p y r o l y s i s t e m p e r a t u r e w a s s t u d i e d b y u s i n g d i ff e r e n t C u r i e - p o i n tpyrolysis foils. When the pyrolysis temperature was 445 and 670°C, theTABLE 3
Measurement range of alkaloids
Alkaloids
Measurement range(ì g)Morphine · HCl
2.5-40
Codeine · H3PO4
1.0-45Dihydrocodeine · H 3 PO4
1.0-45
Cocaine · HC1
1.0-27

Retention time
(min)
3.7
3.8
3.8
3.9

peak area was a maximum. A pyrolysis temperature of 670°C gave themaximum sensitivity, however (Fig. 4).
The pyrolysis time studied was 2, 3, 4, 5 and 8 s. The optimum pyrolysis
time is 3-5 s (Fig. 5).
In this experiment, the pyrolyses of alkaloidal narcotics were carried out
as follows: pyrolysis temperature is 670°C; the mixture ratio of iron andsodium carbonate is 4: 1; the amount of mixture is 30 mg; pyrolysis time is4s.
Determination of pyrolysis products
The determination of alkaloidal narcotics by GC produces a spectrum ofseveral peaks, one of which had a retention time identical that of to3,4-dimethyl-l,2-dihydroxybenzene (3.7 min). The measurement range ofalkaloidal narcotics was about 1-40 /ìg (Table 3). For example, the calibration curve for morphine hydrochloride (we used the commercial drugs) hada s t r a i g h t l i n e w i t h a c o r r e l a t i o n c o e ff i c i e n t o f 0 . 9 9 9 8 , a n d t h e r e l a t i v e
standard deviation for the pyrolysis of morphine hydrochloride (32 ìg) was
2.5% (n= 10).
Extraction and pyrolysis of cocaine in human urine
The cocaine hydrochloride (13.4 /ìg) added in human urine was extractedwith dichloromethane under alkaline conditions and was added to a solutionof hydrochloric acid in ethanol. The solvent was evaporated on a hot plate atabout 100°C and 0.05 ml of water was then added to the residue. Iron andsodium carbonate were added to the pyrolysis foil. The pyrolysis was carriedout at 670°C.
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