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Vol. 17, No. 6
1A'D US TlZIAL A N D ENGILVEERI NG CIiBMISTR Y
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The extensive use of immiscible solver- ,or the extraction of solutions and the need for simple automatic device8 t o accomplish this purpose is pointed out. The general employment of the hand-shaken separatory funnel for Hquid extraction is evidence thst none of the numer+us dei-Ires hitherto described have satisfied this need. Several extraction devices (some very simple) are de-
scribed and illustrated with data as to their efficiency. Types suitable for both heavier-than-water and lighter. than-water solvents are shown. In some the solvent vapor goes first to the condenser and then enters the aqueous liquid after condensation, in others the solvent is introduced directly into the aqueous liquid as a vapor and is there condensed.
X'I'PACTIOX of solutions with iminiscible solvents
tlic spider is now sealed off as close to the wires as practicable ( d ) , Upon dissolving the wire in nitro-hydrochloric acid, uniform openings of the size desired are formed ( e ) . Soft glass is not so suitable for this purpose ns hard glass, as the soft glass tends to flow over tlie wire, thus making subsequent soiuiion in ncid rlificiilt. Pyrex is a euitnblc $ass for this
finds wide :ipplication in nndytical chemistry, particularly in pharmaceutical annlysis. Numerous nuh i m t i c devices for accomplishing this purpose Iinve been ciev k d . ' ~ * Whether it be for lack of effect,ivencss, coinplication ,of construction, or limitnt,ion on t'hc automatic fcnturca, none of these hn:.c conic into general use, nt 1cast.iil Amcricnn laboratories. The "simple type" tlcscribcd in this paper is an improved form of the Baas and Uoscmnn type. Its simplicity of construction, ndiiptrhility, atid efficacy have rnadc it very useful in tile Drug Control 1,a)Jorntory for extracting a variety of preparations containing alkaloids, such as Ruid extrncts and .tinctures of nus yomica, l)elladonnci, ipecac, and even opiuni, d t i i o u g h its usefiiliicss is by no n ~ c n n siiinitcd to alkaloid cs,tractions. Tiic dcttiils of coristruct~ionfor each of the form!: have 1)ee.n cnrcfally worked out, with R view to maintaining :i rapid iiirtl continuoils supply of freeh solvent in the forin of fine globules or spray. The heating apparatus gcncrnlly cmploycd is a GO#-watt electric hot plntc, nbout 15 cm. i n diamet,er, cscept for estractions with ether, for which tiic .steam bath is used. X layer of molten solder is used as B fluid metitllic contnct to increase the speed of boiling of t,hc solvcnt. This is pnrticularly iiacfcl with benzene ns a solvent. Cork stoppcrs co;.ercd with tin foil have been found satiufactory for the two coiincctions. One clninp only (ior the condenser) is riccessary to hold the npparatus. The cstractor is held firmly enough by the cork connection or, in the forin illustrated i n Figlure 3, is set into the mater-cooler jnckct. Apparatus
SIMPLETYr~E-In the simplc type of apparatus (Figurc
1)
She same jacket, condcnser, rind boiling flask are used for light a n d hcavy solvents. For light solvcnts the funnel tubc ( b ) , containing vcry srnril! openings a t its lower cnd, is used i:i &hejnckct, RS diown in /3. For heavy solvents, as shown iri C, the wide tube (c) open %thoth cndv is used. The munricr in which tlic c x h c t o r s fiinctioii is sliown by the illustnitions. The construction of t h e funnel tubc ( b ) is shown in Figure 2. For the purpme of formirig i n tlie l o w r cn? of this tubc n Inrgc! number of vcry sninll opcniiigx, which brcirk the solvt!nt ititn a spray of minute droplets, n "spider" ( a ) mndc of niclirome wire of thc proper diameter iri nttschcd to the cxpnndcd crid of thc funnr:I tithe (6). Ailother piccc of tubing is tlicn scnlcd to this cxpmtlcd d, SYJ !is to loavc the wirca of the spicicr projecting through thr: wrtlls ol the tubc ( c ) , The tube IJClOW 1 Xeceivcd hfnrch 13, I W B . I'resentrd h f o r c t h e Dividon of Clicfnir. t r y 5f hfrdicinnl Prwltictr n t f l i c 09th X c e l i n g of the Amcricnn Clicinicnl % x ! c t y , Rnltinrwe, Md., April 0 t o Io, 1926. e Numbers in f r r l refer l o bililiogrnphy n t cnrl of Rrlicle.
o
b cJ*.-
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BND UETRIAL AND ENGINEEBINC CHEMIETRY
June, 1925
portion of the apparatus. On account of the small diameter of the wire used (031 rnm.), the spider cannot be made of copper because that metal would not withstand the heat necessary to soften the glass. Although nichrome is resistant to the action of individual acids, there is no particular difficulty in dissolving it in boiling aqua regia. The spider is readily made as follows: Eight pieces of the nichrome wire 6
a
C
d e
#& Q
Figure 2
about 2.5 cm. long are made into a bundle by binding a t the center with a short piece of stout copper wire, bent over and pressed tight by pliers. The sixteen branches are then spread out so as to extend radially from the copper band as a center and spaced equally apart, as shown in a (Figure 2). The completed funnel tube may be tested by Iorcing water through it under slight pressure, as the head is insufficient for water, although quite adequate for hot solvent. These two extremely simple types of apparatus are sufficient for the great majority of extractions required in pharmaceutical analyses For use with substances more difficult to extract there are illustrated two types, in which the solvent enters the aqueous solution wholly or partly in the form of vapor, thus producing vigorous agitation and more rapid extraction than is obtained by the simple forms. FORSOLVENTS LIGHTERTHAN WATER(FIGURE 3)--This apparatus is more complicated and difficult to construct than the simple types shown in Figure 1. It is advantageous to provide the trap with a little mercury in order t o insure smooth operation. The only part of the apparatus that is clamped is the water-cooler jacket. The extractor is simply set into it as indicated and is sufficiently secure without further clamping. The small condenser, an added precaution, is almost unnecessary. By controlling the speed of supply of condenser water and the rate of heating of the flask, the temperature of the contents of the extractor can be varied over a fairly wide range. FORSOLVENTS HEAVIER THAN WATER(FIGWE 4)-The inverted thimble, C, is used with the extractor, and solvent vapor is forced through a shallow layer of the aqueous liquid to be extracted before going into the condenser, thus creating considerable agitation, the extent of which may be controlled by the speed of boiling. This extractor can be used without the thimble for heavy solvents (as a simple form), but it has no particular advantage over the simple type.
518
been fitted to a 200-cc. Erlenmeyer flaak; 2 GC, of ammonia (hydroxide) solution and about 25 cc. of benzene me added, and the whole is shaken slightly to prevent the settling of any solid matter on the bottom of the extractor. The narrow funnel tube (A, b) (with the fine holes a t the bottom) is introduced, and benzene is added until about 50 cc, overflows into the flask. The extractor is then arranged BS shown in B. When the apparatus is in full operation there should be brisk boiling. Note-Care should be taken not to permit the boiling t o go so rapidly a5 to cause emulsion to be carried over into the flask. If this cannot be prevented, the extraction is allowed to proceed to completion, when the extracted aqueous liquid is discarded and the contents of the flask returned to the extractor, the flask washed with about 20 cc. water and some fresh benzene and brought into the extractor, and the extraction is repeated.
A fine spray of benzene should rise through the aqueoue layer. The extraction is carried on for 1 to 2 hours. When complete, the benzene overlying the aqueous Payer is Eieparated and added to the main concentrate in the flask connected to a clean, dry extractor ( A ) ,and the bulk of the solvent is recovered. The remainder of the solvent in the flask is then evaporated on the steam bath, the residue of alkaloids is taken up in a little absolute alcohol, and the evaporation is repeated to remove all traces of ammonia. The alkaloid is determined in the usual way by titration, using methyl red as indicator
I
b
a
=#=p/, condenser
Application to Fluid Extracts and Tinctures of NuxVomica, Belladonna, Etc. PREPAR.4TIQN OF SOLTJTION2-h order $0 obtain a clean alkaloidal residue by one extraction, the fluid extract or tincture is de-alcoholized and partially purified as follows: 25 cc. fluid extract (for tinctures use 100-cc. sample) and 3 cc. 1 N sulfuric acid are evaporated on the steam bath to about 10 cc., and the resulting concentrate is diluted to 50 cc. and filtered. EXrTRACTIQN-ApparatUS shown in B, Figure 1, is used. Twenty cubic centimeters of the filtrate (representing 10 cc. origiinal sample) are pipetted into the extractor, which has
Figure 3
Ipecac preparations are treated in a similar manner, but the solvent is ethyl ether, since the Pharmacopeia1 standard is based on the ether-soluble alkaloids. Twenty cubic centimeters of fluid extract with 5 cc. 1 N sulfuric acid in a 100-cc. volumetric flask are evaporated to a small volume, diluted, etc., and a 20-cc. aliquot of filtrate (representing 4 cc. original fluid extract) is taken for the extraction,
INDUSTRIAL A N D ENGINEERING CHEMISTRY
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Vo1. 17, No. 6 Table I1
--ALKALOIDS(A) (B) Declared No. tablets Extraction Mechanical SOLVENT standard used for by hand extractor USEDIN PRODUCT Grams analysis Gram Gram METRODBo 1-100 50 0.0240 0.0229 Benzene 0.0243 0.0236 Benzene 1-100 50 0.0264 0.0271 Benzene 0.0257 Benzene 1-100 50 0.0257 0.0271 Benzene 0.0257 0.0257 Benzene 1-8 16 0.0969 Chloroform 0.0952 0.0978 Chloroform Codeine sulfate 1-2 4 0.1148 0.1141 Chloroform 0.1148 Chloroform 10 0.0705 0.0720 Chloroform 1-8 0.0750 Chloroform 1-4 6 0.0857 0.0871 Chloroform 0.0872 Chloroform Morphine sulfate 3 1-4 5 0.0698 Chloroform 0.0705 0.0711 Chloroform Mg. Mg. 14.38 13.85 Benzene (a) 13.85 Chloroform (b) 14.03 Gram Gram 1-40 50 0.0608 0.0630 Benzene Strychnine sulfate 0.0617 Benzene 11-8 0.0468 0.0460 ' Benzene Chloroform was used as solvent in all cases in Method A.
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