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Related article: its extractive by the alkali and water. So ammonia water or Purchase Norvasc bicarbonate
solution is an easier and more effective menstruum to transfer the residue
to the ethereal or chloroformic solvent.
Sand is not a good absorbent, and therefore fails of its chief purpose. Purchase Norvasc
Sawdust is much better, leaves less residue Purchase Norvasc adhering to the dish, and pro-
duces a powdery instead of a lumpy mass to extract. I Purchase Norvasc have never felt
the necessity of preparing the sawdust by washing with alkali or ether,
then with acid and drying. Ordinarily, carpenter's sawdust, just off the
floor, will serve every purpose.
The next general step is extraction of Purchase Norvasc the alkaline etheral or chloro-
formic solution with acid. Sulphuric acid is directed in every instance,
and in normal volumetric solution or dilutions thereof. But hydrochloric
acid is better in some cases (Cinchona, Coca, Physostigma), because it
removes the alkaloid more rapidly. Why not use it ? the results are the
same.
Then the very weak acids are prone to emulsify, sometimes much too
easily. Stronger acids may be preferable for this reason. Physostigma is
particularly troublesome, and I prefer to use ten per cent, hydrochloric
acid for each shaking. It conduces to peace of mind and cheerfulness as
well as to facility in results.
Emulsions are the irritating factors in alkaloidal assays. I have often
succeeded in breaking an alkaline emulsion by a liberal use of solid potas-
sium carbonate, and an acid emulsion by strong acid. "Simi/ia simiiibus
curantuTy^ but not in homeopathic doses.
The use of stronger acids also results in some cases in keeping the total
quantity of liquids used down to a minimum. Aside from the question
whether a moderately strong acid combines more quickly and completely
with the alkaloids, the quantity needed for each shaking is smaller because
emulsions are less liable to form. And the smaller the quantity of one
liquid, the less is required of the next immiscible solvent for the subse-
quent extraction. So a 5 per cent, acid may be much quicker than a 1
per cent, or weaker.
A third general consideration is that when a fluid extract or tincture is
evaporated to drive out the alcohol, then mixed with a dilute acid and
filtered, as in the assay of fluid extracts of aconite, ipecac, etc., the addi-
tion of a clarifying agent is always advisable. It not only insures a clear
filtrate, which is doubtful without it, but it prevents the clogging of the
filter, which is likely to occur without it. Talcum, kaolin, infusorial earth
or paper pulp, are each suitable. This step should then be continued
until the filtrate gives no reaction with Mayer's reagent.
Finally, a word about the complete extraction of alkaloids from aqueous
or ethereal solvents. The general directions are to continue shakings with .
Digitized by VjOOQIC Purchase Norvasc
820 MINUTES OF THE SECllON ON SClENTinC PAPERS.
the immiscible liquid until the aqueous solution, made acid, if necessar>%
gives no Purchase Norvasc precipitate with Mayer's reagent. But aconite, coca, ipecac and
some others contain alkaloids which are not easily soluble in ether, and
are not intended to be included in the assay.
So with these drugs it is impracticable to test the aqueous solution.
Nux vomica also continues to respond to Mayer's reagent after all the
strychnine is removed. Such Purchase Norvasc drug assays must have the test applied to the
residue obtained by evaporating a small amount of ethereal or chloro-
formic solution, after dissolving this residue in a drop or two of weak acid.
Coniine is much more sensitive to Wagner's than to Mayer's reagent, and
caffeine responds to iodine solution, in acid solution, but not to Mayer's.
Thorough shaking is also necessary before the test is applied. This
seems so obvious as to make attention to it superfluous, but I have reason
to believe that insufficient shaking is often the reason for low results re-
ported. In one or two instances the Pharmacopoeia directs the shaking
to be continued for one or two minutes. It were better if all shakings
were to be directed to continue two minutes. Solution is not an instan-
taneous Purchase Norvasc process, and in drug assays it takes effect mostly during the shak-
ing. . Hence three portions of solvent thoroughly shaken for two or three
minutes each, may accomplish as much as five or six portions with short
agitations on each. In this work the rule Purchase Norvasc to " make haste slowly " well
applies.
Aconite,^ The chemical assay of aconite has been much criticised, but
that the method of the Pharmacopoeia has a real value can scarcely be de-
nied. It could well be supplemented by the Squibb physiological test,
which would add much to its value. The physiological test would be best
applied to the drug-percolates or extract, and also checked by two or
three observers, since individual susceptibility varies (in the same indi-
vidual), and the test is so quickly made. The drug and fluid extract
should respond to a dilution of not less than i in 800, and the tincture at
not less than i in 80.
In the chemical assay, it is well to weigh the alkaloidal residue before
titrating, because the tendency on this assay is to read the end-reaction
too quickly. When one gets more alkaloid by titration than by weighing,
as may easily happen, the warning can be immediately heeded. Or it
may be that most of the active aconitine has decomposed into the antag-
onistic aconine, of lower molecular weight and higher titrating value.
A re- reading of the end point in titration, and supplemental physiological
test, will together solve the problem for practical results. In the assay of
the fluidextract, a clarifying agent is necessary for the first filtration.
Belladonna^ Hyoscyamus, Scopola and Stramonium, The processes for
the drugs are satisfactory when a careful use of Mayer's reagent is used to
insure complete extraction. On the preparations, the process is all right
if the preparation is fresh, but, as pointed out in another paper ("The
Digitized by VjOOQ IC
COMMENrS ON THE ALKALOiOAL ASSAY MO'HODS OF THE U. S. P. 82 1
Keeping Qualities of the Alkaloidal Fluid Extracts and Tinctures"), with
an old preparation the process does not extract all of the alkaloid unless
alcohol be added. The process may be modified in this way. When the
chloroform Purchase Norvasc washings (shaken with the fluid extract or concentrated tinc-
ture) cease to give a residue which reacts with Mayer's reagent in acid
solution, add lo Cc. of alcohol to the separator, and a fresh portion of
chloroform and again shake. Evaporate about ^ Cc. of the chioroformic
solution which has separated, on a watch glass, add two or three drops of Purchase Norvasc
diluted sulphuric acid, then a drop of Mayer's reagent. If a precipitate
occurs the extraction must be continued until chloroform ceases to remove
any alkaloid from the aqueous-alcoholic liquid.
Cinchona, In order to secure constant results in ether-soluble alka-
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