Gas chromatography-mass spectrometry in forensic chemistry for identification of substances isolated from tissue

Summary The use of combined gas chromatography-mass spectrometry in forensic chemistry is demonstrated in 13 cases where various substances had to be isolated and identified, the substance was present in small amounts in some samples while in others the sample available was very small. In other instances a rapid and certain identification was important. The results are compared with data obtained by conventional procedures. The advantage of this method is discussed and it is emphasized that a collection of mass spectra of all common substances searched in forensic chemistry simplifies the indentification. Reference mass spectra of some drugs are given.

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Zusammenfassung Die Anwendung einer kombinierten gaschromatographischen und massenspektrophotometrischen Methode in der gerichtlichen Chemie wurde anhand von 13 untersuchten Fällen diskutiert. Verschiedene Substanzen, z.T. in kleinsten Mengen, wurden isoliert und identifiziert. Die erhaltenen Ergebnisse werden mit den Resultaten der konventionellen Methoden verglichen, zudem wird anf die Vorteile der GC-MS-Kopplung hingewiesen. Gleichzeitig werden einige Massenspektren wiedergegeben.Eine Massenspektrensammlung von den in der gerichtlichen Chemie häufig anzutreffenden Substanzen ist für eine rasche und einfache Identifizierung erforderlich.

     

Weight loss and shock-elicited aggression as indices of morphine abstinence in rats

Weight loss and shock-elicited aggression have been compared as quantitative indices of morphine abstinence in rats. A range of doses of morphine was administered to rats by i.p. injection twice daily for 12–15 days. After injections were stopped, morphine-abstinent rats lost weight precipitously, and showed an increased frequency of fighting in response to aversive stimulation (foot-shock). Recovery of weight appeared complete after 15–20 days but a significant increase in aggression was found at 18 days post-withdrawal; this virtually disappeared after 52 days. Both the amount of weight lost and the frequency of fighting increased as a function of the previous maintenance dose of morphine; the effective dose range appeared similar for these two indices. Weight loss was much less variable than fighting, had the advantage of rapid, objective measurement, and appeared to be the more reliable index of abstinence.     

Influence of naloxone and methysergide on the analgesic effect of clomipramine in rats

The effects of the tricyclic antidepressant clomipramine were studied in two analgesic tests in rats: (1) vocalization threshold response; and (2) scored behavioral response to electric shock to the tail. Clomipramine (20-50 mg/kg i.p.) produced analgesia, decreasing behavioral response scores and increasing vocalization threshold. Morphine also reduced the response scores in the second test. Naloxone (0.8 mg/kg i.p) or methysergide (20 mg/kg i.p.) (no effect when given alone) abolished the analgesic effect of clomipramine as evaluated by vocalization threshold response. Naloxone alone (0.6 or 2 mg/kg i.p.) increased the behavioral response at 20 and 30 V but did not modify the score at 40 V. Naloxone reduced the analgesic effect of clomipramine or morphine in the behavioral test. These results suggest that the analgesic effect of clomipramine could involve both serotonergic and endorphin central systems.     

Naloxone does not antagonize leukocytic pyrogen

In a crossover experiment, cats were given third cerebral ventricular injections of 500 microgram naloxone hydrochloride or saline vehicle followed in 15 min by i.v. injections of saline solution or leukocytic pyrogen. The pyrogen produced comparable fevers after both saline and naloxone pretreatment. Intravenous administration of naloxone hydrochloride (5 mg/kg) likewise did not prevent febrile responses to leukocytic pyrogen. These results indicate that endogenous opioid peptides are not likely central mediators of pyrogen-induced fevers.     

Fatal combined anileridine-pethidine poisoning. A gas chromatography,thin layer chromatography and mass spectrometry investigation

Summary Anileridine and pethidine were established by gas and thin layer chromatography and mass spectroscopy. In the mass spectrum the main peak of anileridine is found at m/e 246 and that of pethidine at m/e 71. The determination was made by gas chromatography from the blood, urine, liver, muscle and stomach contents.

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Zusammenfassung Anileridin und Pethidin wurden mittels Gas- und Dünnschicht-chromatographie sowie massenspektroskopisch festgestellt. Im Massenspektrum liegen die Hauptspitze von Anileridin bei m/e 246 und diejenige von Pethidin bei m/e 71. Die Bestimmung erfolgte gaschromatographisch aus Blut, Harn, Leber, Muskel und Mageninhalt.

     

Effect of dopaminergic stimulation or blockade on morphine-withdrawal aggression

The effects of morphine (10 mg/kg), nalorphine (1 and 10 mg/kg), and naloxone (1 mg/kg) were studied on the neocortical release of acetylcholine (ACh) in midpontine pretrigeminal transected rats. Morphine and, to a lesser extent, nalorphine decreased ACh release. Naloxone was ineffective alone but antagonized the action of morphine.Predoctoral fellow with scholarships from Laval University and Province of Quebec, Canada.This research was supported in part by USPHS grant MH-11846.     

Morphine induced increases in the incorporation of H-thymidine into brain striatal DNA

³H-thymidine uptake into DNA fractions of rat brain regions was measured following in vivo administration of (methyl-³H)-thymidine and morphine. Acute morphine administration (10 mg/kg; 30 min prior to ³H-thymidine) increased incorporation of ³H-thymidine into DNA of rat striatum. This effect was antagonized by naloxone (1 mg/kg). Further, the observed change in incorporation of ³H-thymidine into DNA in striatum could not be accounted for by differences in the local availability of the label in morphinized rats. An autoradiographic study revealed that the ³H-thymidine was localized in nuclei in cells of the sub-ependymal layer lining the lateral ventricles, an area of glial cell proliferation in adult rats. No change in ³H-thymidine incorporation into DNA was observed in any area of the brain in morphine-addicted rats or in rats undergoing naloxone-precipitated withdrawal. The results indicate that opiates may induce permanent anatomical changes in the brain, including alterations of neuroglial interactions.     

Peripheral stimulation in mice induces short-duration analgesia preventable by naloxone.

Peripheral stimulation was applied to mice by mild caudal electrostimulation, by mechanical pressure or by footshock for 30 sec, before testing on a 52 degrees C hot plate. Reaction times to paw lick and to escape from the hot plate were recorded. Analgesia could be elicited and measured by these procedures. It was of short duration, declining in a minute, and was antagonized by low doses of naloxone. The analgesia measured by the escape reaction time could be elicited after multiple caudal electrostimulation as well as in morphine-tolerant mice, and it could still be reversed by naloxone. An opioid link is thus involved in this phenomenon, which also supports the notion of more than one opioid pathway existing in the brain. The short period of analgesic cover afforded in the face of noxious stimuli would permit aversive action to be taken in nature and thus might represent the prime functional role of enkephalins in the brain.     

The role of the cholinergic system in the development of increased naloxone potency in mice

Pretreatment of mice with the anticholinesterase (anti ChE) drugs tacrine or physostigmine augmented the antinociceptive potency of morphine given 3 h later, but had no effect on the antagonist potency of naloxone. Pretreatment with either of these anti ChE drugs together with morphine not only augmented the potency of a subsequent dose of morphine, but also enhanced the antagonist potency of naloxone to a greater extent than after pretreating with morphine only. Neostigmine did not affect the potency of either morphine or naloxone, suggesting that this phenomenon involved central cholinergic mechanisms. Atropine prevented the increase in naloxone potency caused by morphine pretreatment, and greatly reduced the effect of morphine plus the anti ChE drugs. The effects of these various pretreatments on the development of “acute dependence” to morphine was also studied. None of the three anti ChE drugs caused any change in this phenomenon, as tested by naloxone-precipitated jumping, although this was significantly increased by pretreatment with either atropine sulphate or atropine methyl nitrate. It is concluded that the increase in naloxone potency following morphine pretreatment involves both a cholinergic mechanism plus narcotic analgesic action. This phenomenon does not seem to be related to the development of either acute tolerance or acute dependence.     

Extracellular recording from the guinea-pig myenteric plexus and the action of morphine

Extracellular recordings were made with glass suction electrodes from neurons in isolated ganglia of the myenteric plexus of the guinea-pig ileum. The activity recorded was considered to arise in neuronal somata as a consequence of the mechanical contact with the recording electrode. The spike activity was depressed by normorphine (10 nM—1 μM) and this action was prevented by low concentrations of naloxone. Morphine remained effective in solutions which contained 1 or 12 mM K⁺. The findings support other evidence that morphine acts by hyperpolarizing the soma membrane of myenteric neurons, but do not elucidate the ionic mechanism of the effect.