E. G. C. Clarke

MICROCHEMICAL TESTS FOR THE IDENTIFICATION OF ALKALOIDS

OF the methods available for the identification of minute quantities of alkaloids, the production of microcrystalline derivatives of characteristic form and habit is generally acknowledged to be the most delicate and the most reliable. Colour reactions, while sometimes of great value as confirmatory tests, are not of universal application and suffer from the defect that small traces of impurity may give rise to misleading results. Physiological tests, using living animals, are, on the whole, less sensitive than chemical tests and can only be carried out by persons holding a Home Office licence. Paper chromatography’ thohgh promising, is as yet largely untried. Microcrystalline tests have been developed by many workers including Wormley2, Stephenson3, Fulton415, WhiteE, Wagenaar’, and OliverioE, but this development has consisted in the introduction of new reagents rather than in the elaboration of the technique itself. Tests have usually been carried out by placing a drop of the test solution on a microscope slide, adding a drop of the reagent, and examining under low magnification. As this method does not give satisfactory results when dealing with quantities of less than 1 mg., the technique described below has been introduced for the identification of alkaloids when only a few pg. are available.

The Isolation Of The Toxic Principle Of æNanthe Crocata

1 A method is described for the preparation of highly toxic crystals from water dropwort root. Previous workers have only reported oils or resins of far less toxicity. 2 These can be purified by recrystallisation, or by chromatography on an alumina column, when a single steel‐grey zone is obtained. These purifications do not alter the melting point or the crystalline habit. 3 The crystalline material, m.pt. 80° to 81° C., is insoluble in water, light petroleum, alkalis, and diluted mineral acids, but readily soluble in chloroform, ethyl alcohol and ether. 4 The crystals are extremely unstable, yielding an insoluble infusible resinous material, with no pharmacological activity. 5 If kept under nitrogen at 4°C., the crystals can be preserved for weeks with little loss of activity. 6 Death after characteristic convulsions follows the intraperitoneal injection of an emulsion of the crystalline material into mice. 7 The A.L.D. is 0°83 mg./kg. of body weight.

MICROCHEMICAL IDENTIFICATION OF SOME LESS COMMON ALKALOIDS

DURING recent years new techniques have been developed for the identification of alkaloids and older techniques have been modifiedlJ, but the tendency has been to describe each new development as applied to the same group of twenty or thirty well known alkaloids. The result is that of the thousands of alkaloids now known, micro tests suitable for medico-legal work have been described for fewer than a hundred. The toxicological chemist must be in a position to give positive identification to any alkaloidal substance that he isolates, and not merely to a selected few of classical forensic interest. This paper describes crystal and colour tests for 40 alkaloids which, although less well known, are all substances that may either be obtained commercially or extracted with comparative ease from common plants ; most of these compounds are referred to by Henry3 or Manske and Holmes4. Of the more recently discovered ones, aquaticine was isolated from Senecio aquaticus by Evans and Rees Evans5, and demecolcine (desacetylmethylcolchicine) from Colchicum autumnale by Santavy and Reichstein6.

Microchemical Identification of Some Atropine‐Like Drugs

Crystal and colour tests are described for 48 atropine‐like drugs.

MICROCHEMICAL DIFFERENTIATION BETWEEN OPTICAL ISOMERS OF N‐METHYLMORPHINAN ANALGESICS

A simple method for differentiating between microgram quantities of optical isomers is described.

A NOTE ON THE FACTORS AFFECTING RF VALUES ON CITRATE BUFFERED PAPER CHROMATOGRAMS

Experiments have been made to determine the effect of changes in experimental conditions on the speed of running of citrate/butanol systems on paper chromatograms.

A two-stage micro-evaporator.

Two devices for concentrating solutions are described. The first reduces a volume of 1 ml. to one of 0.05 ml. and the second a volume of 0.05 ml. to a few microlitres.

A note on the acute toxicity of hydrolysable and condensed tannins.

IN the course of an investigation into the toxicity of the acorn, Clarke and Cotchinl found that acorn tannin had a toxicity comparable with that of tannic acid, but were unable to trace experiments on the toxicity of other tannins. Although these substances had long been regarded as the toxic principles of certain plants, little interest had been shown in their toxicity to man until numerous fatalities were reported after the use of tannic acid in the treatment of burns. Cameron, Milton and Allen2 and others then showed that tannic acid was extremely toxic by injection in laboratory animals, death following severe liver damage. It is important to note, however, that except for some work by Hartman and Romence3 on quebracho tannin, all these experiments were carried out with tannic acid. This substance, usually obtained from galls growing on the oak (Quercus spp.), is but one of many tannins. Broadly speaking, these substances may be divided into two classeshydrolysable tannins and condensed tannins. The former on treatment with mineral acids are readily hydrolysed to sugars and gallic acid or ellagic acid, while the latter condense to yield ill-defined insoluble bodies called phlobaphenes. Tannic acid is a member of the first group. Whether the difference in chemical properties between these two groups of tannins was paralleled by difference in toxicity is the subject of this note.

THE EFFECT OF IMMUNE SERUM ON HÆMAGGLUTINATION BY RICIN

1 The literature dealing with the subject is briefly reviewed. 2 It was found impossible to demonstrate the presence of any specific anti‐agglutinin in the serum of either goats or rabbits immunised against ricin. 3 Large additions of both normal and immune sera inhibit agglutination of the red cells of most species of animals tested. 4 When added in an optimum quantity of approximately 1 per cent. immune serum greatly increases the agglutinating power of ricin towards the red cells of dog, cat, rabbit and guinea‐pig. 5 With the blood of horse, ox, goat and sheep, both normal and immune sera exert a slight promotive effect when added in optimum quantity. 6 The action of immune serum on dog red cells was investigated under varying conditions and the promotive action shown to be specific to ricin and independent of red cell concentration and of pH. It is also independent of temperature, provided sufficient time is allowed for equilibrium to be reached. 7 It is concluded that one cannot explain these phenomena until more is known of the mechanism of agglutination by ricin.

A MODIFIED APPARATUS FOR REINSCH'S TEST

A modified method for the rapid identification of antimony, arsenic and mercury is described.