[441] “The post-mortem Detection and Estimation of Strychnine,” by Allerton S. Cushman—Chem. News, vol. lxx. 28.
“The stomach contents or viscera properly comminuted are weighed, and an aliquot part taken for analysis. The mass is digested in a beaker over night, at a warm temperature, with water acidulated with acetic acid. The contents of the beaker are filtered by pressing through muslin, and then passing through paper. The clear filtrate is evaporated on the water-bath to soft dryness, an excess of ordinary 80 per cent. alcohol added, and boiled ten minutes with stirring, and allowed to stand one half hour at a warm temperature. This extraction is repeated, the alcohol extracts united, filtered, evaporated to soft dryness, and the residue taken up with a little water acidulated with acetic acid, and shaken out with pure acetic ether in a separating funnel. Successive fresh portions of acetic ether are used until the solvent shows by its colour, and by the evaporation of a few drops, that it does not contain extractive matter. As many as twelve extractions are sometimes necessary to accomplish this. Care should be taken in each case to allow time for as complete separation as possible between the two layers. The purified acid aqueous liquid, which need not exceed in bulk 50 c.c., is now returned to the separator, an equal quantity of fresh acetic ether added, and enough sodic carbonate in solution to render the mixture slightly alkaline, and the separator is then thoroughly shaken for several minutes. All the alkaloid should now be in solution in the acetic ether, but a second shaking of the alkaline liquid, with acetic ether, is always made, the two extracts united, and evaporated in a glass dish over hot water to dryness. It will now be found that the residue shows the alkaloid fairly pure, but not pure enough for quantitative results. The residue is dissolved in a few drops of dilute acetic acid, warmed to complete solution, filtered if necessary, diluted to about 30 c.c., and the solution transferred to a small separating funnel; 30 c.c. of ether-chloroform (1-1) are now added, and the separator shaken. After separation the heavier ether-chloroform is allowed to run off, another lot of 30 c.c. of ether-chloroform is added, the separator shaken, and immediately enough ammonia-water added to render the mixture alkaline, and the whole vigorously agitated for several minutes. After separation is complete, the ether-chloroform layer is run out into a clean 50 c.c. glass-stoppered burette. The alkaline water solution is agitated with 20 c.c. more of the ether-chloroform, separated, and this extract added to that in the burette. The burette is now supported over a small weighed glass dish, which is kept warm on a water-bath, and the liquid allowed to evaporate gently, drop by drop, until a sufficient quantity of the pure alkaloid has collected in the centre of the dish to render an accurate weighing possible, or else all of the alkaloid may be collected and weighed at once. After all possible tests have been made upon the weighed alkaloid, the remainder is re-dissolved in a drop or two of acetic acid, a little water added, and the dish exposed under a bell-glass to the fumes of ammonia. After standing some time all the strychnine is found crystallised out in the beautiful characteristic needle-formed crystals. The mother-liquor is drawn off with a small fine-pointed tube and rubber bulb, the crystals carefully washed with a little water and dried over sulphuric acid. The glass dish containing these crystals is kept as the final exhibit, and is shown in evidence. Another convenient exhibit may be prepared by moistening a small filter-paper with a solution of the alkaloid in dilute acetic acid, then moistening with a solution of potassium dichromate: this paper, on being dried, may be kept indefinitely. On moistening it, and touching it at any time with a drop of strong sulphuric acid, a violet film, changing to cherry-red, is formed at the place of contact.”
Should search be made for minute portions of strychnine in the tissues, considering the small amount of the poison which may produce death, it is absolutely necessary to operate on a very large quantity of material. It would be advisable to take the whole of the liver, the brain, spinal cord, spleen, stomach, duodenum, kidneys, all the blood that can be obtained, and a considerable quantity of muscular tissue, so as to make in all about one-eighth to one-tenth of the whole body; this may be cut up into small pieces, and boiled in capacious flasks with alcohol, acidified with acetic acid. Evaporation must be controlled by adapting to the cork an upright condenser.
Should the analyst not have apparatus of a size to undertake this at one operation, it may be done in separate portions—the filtrate from any single operation being collected in a flask, and the spirit distilled off in order to be used for the next. In this way, a large quantity of the organs and tissues can be exhausted by half a gallon of alcohol. Finally, most of the alcohol is distilled off, and the remainder evaporated at a gentle heat in a capacious dish, the final extract being treated, evaporating to a syrup, and using Cushman’s process (ante, [p. 334]) as just described. It is only by working on this large scale that there is any probability of detecting absorbed strychnine in those cases where only one or two grains have destroyed life, and even then it is possible to miss the poison.
Strychnine is separated by the kidneys rapidly. In a suicidal case recorded by Schauenstein,[442] death took place in an hour and a half after taking strychnine, yet from 200 c.c. of the urine, Schauenstein was able to separate nitrate of strychnine in well-formed crystals. Dr. Kratter[443] has made some special researches on the times within which strychnine is excreted by the kidneys. In two patients, who were being treated by subcutaneous injection, half an hour after the injection of 7·5 mgrms. of strychnine nitrate the alkaloid was recognised in the urine. The strychnine treatment was continued for eight to ten days, and then stopped; two days after the cessation, strychnine was found in the urine, but none on the third day, and the inference drawn is that the elimination was complete within forty-eight hours.
[442] Maschka’s Handbuch, Band 2, p. 620.
[443] Ibid.