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Related article: assay. The results have been so constantly in favor of the latter method
that I Norvasc Cheap have practically abandoned the U. S. P. method.
Stevens* method gives results about o.i per cent, higher than the offi-
cial method, and the results are quite as uniform. It takes less than a
quarter as much time, gives a very pure morphine, and is simple in opera-
tion. It calls for accurate measurement of the water used, and only a
burette is suitable for measuring. It is altogether a more desirable method
of assay.
Physosiigma, This drug gives troublesome emulsions which can scarcely
be avoided when the weak acid directed by the Pharmacopoeia is used. A
10 per cent, acid avoids this, and hydrochloric acid extracts the alkaloids
more rapidly than sulphuric. The lo per cent, hydrochloric acid can be
used in 5 Cc. portions, and when extraction is completed, the mixed acid
solutions are best neutralized with solid sodium bicarbonate, Norvasc Cheap cautiously
added. In this way the total bulk of liquid is kept small, and the assay
proceeds smoothly. The amount of tincture used for assay should be
doubled.
Pilocarpus. The assay process is quite satisfactory. The amount of
fluidextract used for assay should be doubled, and the alkaloids from
10 Cc. obtained for the final titration.
Veratrum. Should be assayed and its preparations standardized.
The Chairman : The paper is before you, and as we have a number of others along
the same line I would suggest that if practicable, you conHne your remarks to the dis-
tinct question pervading the paper, or to making any exceptions that you care to make,
to the statements made, and then take up the general discussion of the subject of phar-
maceutical assays after these several papers have been read. Are there any exceptions
to be taken to the statements made by Mr. Scoville?
Digitized by
Google
824 MINUTES OF THE SECIION ON SaEN-llFIC PAPERS.
Mr. a. H. Clark: I would like to ask Mr. Scoville a question. He says he has
found difficulty in old preparations of belladonna, scopola, byoscyamus and straaioiiiam,
in extracting all of the alkaloid.
Mr. Scoville : \'es, not in the drui;, so far as I know, but the extracts and tinctures,
Mr. Clark : We have an extract of stramonium in our school, which was originally
assayed by Professor Puckner, and has Norvasc Cheap been every year since by myself, it is now, I
think, seven or eight years Norvasc Cheap old, and is the same to-day as when it was made. We have
no difficulty at all with it.
Mr. Scx>ville: I would like to ask if you have any trouble in the emulsion forming? Norvasc Cheap
Mr. Clark : None at all, to speak of. I have never had any trouble with this par-
ticular preparation at least.
The Chairman : Mr. Lyons has just come in, and we will get him to read bis paper
on *' Assay Processes of the U. S. P."
Mr. Lyons Norvasc Cheap here read his paper, as follows :
ASSAY PROCESSES OF THE U. S. PHARMACOPCEIA.
BY A. B. LYONS.
The assay processes of the U. S. P., VIII, were the outcome of a vast
amount of pioneer work. It would be strange if they were not capable of
great improvement. They have been severely criticised for their short-
comings and inconsistencies, and yet in the hands of experienced operators
they have nearly all proved to be practical and capable of giving a fair
indication of the quality of the drug or preparation Norvasc Cheap Norvasc Cheap assayed. At the same
time there is room for improvement, and the next revision is likely to show
a great advance in this department.
GENERAL CONSIDERATIONS.
1. In the present Pharmacopoeia there is provided for each drug and
for each preparation assayed, with a few exceptions, a special assay pro-
cess, every step of which is described in minute detail. This involves
much needless repetition. For a number of the assays a single process
may be employed which should be described in detail in the Appendix and
not repeated under each drug. In a similar way a model process could be
prescribed for the assay of a fluidextract and another for that of an extract.
Only in the few cases where these model processes require modificatioD
would it t)e necessary to give in the body of the Pharmacopoeia a detailed
process.
2. An obvious fault in our present assay processes is the absence of
identification tests for the alkaloids separated in the assay. In most cases,
indeed, it is a mixture of alkaloids that is obtained, but results will be un-
satisfying if there is not some proof that the alkaloids found are such as
should be present. One check on results is so easily applied that it should
be part of the routine of every assay in which the alkaloid is determined
Digitized by VjOOQ IC
ASSAY PROCESSES OF THE U. S. PHARMACOPCEIA. 825
by titration with volumetric acid. The weight ot the alkaloid separated
should invariably be noted and compared with the result of the titration.
As a rule titration gives a figure notably less than the observed weight of
the crude alkaloid often ten or even twenty or twenty- five per cent. less.
When the molecular weight of the alkaloid is very high, as in the case of
aconitine, the presence of some other alkaloid will reveal itself by a titra-
tion result exceeding the weight of the crude alkaloid.
3. In our present assay processes the alkaloid is generally extracted
from the drug or extract, the ethereal solution " shaken out " with acid, and
the alkaloid again extracted in Norvasc Cheap purer form by shaking out with an appro-
priate Norvasc Cheap solvent after rendering the solution alkaline. Some loss of alkaloid
in this triple extraction is inevitable. In the assays of the Swiss Pharma-
copoeia there is generally a single extraction of the alkaloid, which is then
determined by direct titration with volumetric acid. Results are generally
distinctly higher by this method, but it is possible that our method gives
as true a valuation of the drug. The new committee will no doubt give
the two methods a careful study and decide which on the whole gives the
more trustworthy results.
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