capturing effect$:. For this work the sample should perhaps be interjected between electrodes B and C to take full advantage of secondary electrons. This study has demcinstrated that the I,osition, glo,v gas go,,., I,olarity, and potential on each eleci-rode are critical, affecting not only sensitivity but also II-ell rexulated linearity and noise. poivc>rsu1)lilies and (soncentric electrodes are r e c o m n l e n ~ e tfor ~ a
dissipate its enormous heat from the discharge.
Filla’lyj the be shielded froin thermal drafts, yet be able to
( 2 ) Lossing, F. P., Tmaka, Ikuzo, J . Chem. Phys. 2 5 , 1031 (1955).
ACKNOWLEDGMENT
The author thanks Maynard D. Lay for his technical assistance.
( 3 ) Lovelock, J. E., ASAI,. CHEW 33,
162 (1961). (4) Lovelock, J . E., S u t u r e 188, 401 (1960). ( 5 ) Lovelock, J . E., Research and Deuelopment, October, 1961. (6) Ongkiehong, L., “Gas Chrornatography, 1960,” R. P. W. Scott, Ed., p. 11, Butterworths, London, 1960.
LITERATURE CITED
(1) Loeb, L., “Basic Processes of Gaseous Electronics,” I’niversity of Cuhfornia
Press, Berkeley, 1961.
RECEIVEDfor review 1Iay 6, 1064. Accepted June 23, 1964. Presented March 2, 1964, at The Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Pittsburgh, Pa.
Determinaition of Optimum Solvent Systems for Countercurrent Distribution from Paper Chromatographic Data Binary Organic Solvent/Formamide
Systems
EDWARD SOCZEWINSKI, ANDRZEJ WAKSMUNDZKI, and WIESLAWA MACIEJEWICZ Department o f Inorganic Chemistry, Medical Academy, lublin, Staszica 6, Poland
periments confirm the possibility of approximate estimation of optimum extraction systems from chromatographic data obtained with papers impregnated with formamide.
M O ~ I’M E
- --- - -
--. - --. SlNJOhJARV -
I
of 1)ubIic;itions ( I , 2, 5-7, 9.IO), attenilits have been made to estirnatc suital)lc r s t i w t i o n system< from 1iali(~. c,hromrttoRi,:~iihic data. The basic cmtlition for sucah a method is a liartition nicrhariisni o:! the chrornatoI’ai,tic-ularly successful results h a w 1jee.n otitairwd for a number of alkaloids c.hmiiatogral)hed by the nioist tiuffered 1ial)er method ( 8 ) . F o r ~ i a n i i d r - i r n ~ ~ r ~ ~ gpapers i ~ a t e ~are ~ often u s d in the c.hroriiatogial,h. of in the method of g i v m by \T’aldi viciv of the analogy bet\wen c~h~oinatogra~~liir and c a v a d e 11roc~~sscs which lici~niit~. thr estimation of ,stiitalile ,solvent mc~thods, nonaqum containing forrrianiitle as t h r Iiolar pha,- and c~oriiitc~i~c~~iricrli dist,iiliution is piwented in 1~igur.c1. .In optimum system for paper liartition shotiltl also chromatogral)hy optirnum for Craig’s method provitlvtl that identical rorniio+itions of phase; aye used in both methods at identicad ratio of volumes of tht, two phases. J3y neglecting any of these cwiditioiis, changes in the I)ai‘tition are introtlticwi which may affect the efficiency of srparations. .I rhxnxr of the volunic~ ratio ( T ) may l i t rorrcrtcd a siiital)l(, change of pH of the water phase, or of the coml)osit,ion of the niiscd Iihasc. AI theoretical treatment of the calculations involved is given in the first p:ipei,s of the series cited ( 6 , 7 ) .
rf,, =
I(~L‘-~ IZ I’
1 - If,.
=
log I i r
L’OL. 36, NO. IO, SEPTEMBER 1964
1903
maximum of papaverine occurred at, a lower fraction number than expected, No. 12 instead of No. 15 from data in Figure 2b. This divergence was probably caused mostly by evaporation of chloroform from the less polar phases, which vias' difficult to avoid. ;is can be seen from Figure 2b, the partition of papaverine is sensitive t o even slight changes in the composition of the mixed phase. The second peak is flattened in the horizontal direction, which can also be explained by the gradual evaporat'ion of chloroform so that a kind of spontaneous gradient, elution must, have occurred. The System Cyclohexane Benzene/FA. Twentyf-our transfers were made using equal volumes of the two phases; t h e binary Ilhase was of the optimum composition as estimated from Figure 3b. The starting band was formed by dissolving 100 mg. of
PAPAVERINE
0
+
I 0
02
04
06
OB
1/01 FRACTION
OF CHCJj
Figure 2. ( a ) Diagram of RF vs. volume composition for the system cyclohexane chloroform/FA. (b) Same data, R t f vs. composition plot
+
-__
R.lf
- - - - IogK
log K '
+ log K "
lineh i n Figurc 23 diverge t o the right, 1 ) c ~ t t c ~sq)arations r were to I F cspwtcd at somewhat higher 1)ewentagrs of chloroform in the mixed 1)hasp ( 5 ) . .\nalogous diagranis for thc , lohexanc benzene ,IF.\ w e prescntcd in Figure 3. For r = 1 the optimum comliosition of the mised ilhase is 77yoof benzene 23 v. v. yc of cyclohexane. Except for codein? in the fi (Figure 2b) , the relationshi us. volume romposition are rellresented by approximately straight lines, in good accordance with the formula derived
+
+
o1)timum comliositions, as estimated from the paper chromatogra1)hic data, were etn~~loyetl in comitercurrent dist i,ihition ~ r o c e s h c on ~ a scrnil,i.cl)arativi, scalr, (Craig's countcrc~uiwnt distriliution. fundamental proccdiiro). The System Cyclohexane Chloroform/FA. Sistecn transfer.: were carrictl out using eqiial voluinrs of two ~)liasc.h,10 10 ml.; the misctl solvent conhtitritcd the ul)pcr 1)ha.e. .As t h c %tartin%b a n d , 100-nig. samplcs of ear11 nlksloid wi~rc~ ili**olvctl in tlic cwntcnts of t l i c element S o . 0 of Craig*< all-%lash a p p a r a t u < a t tlie hcyiiining of tlie run. 'I'hcl Ijolai. 1)hasw iwrc dilutcd lvith wa t (3r anti est i'aitt cd t \vice \vi t h c.hloi~form; the c.sttxcts ivcrc cotnbincd \\-ith the rexl)cc~tivccycloh(~sanc~ frac3tions. 'I'hr. fractions \\-cI'c~ t1it.n cstracted tn-ice with water to twnove ally tracw of foi,maniide and dried t o cmnstant wcliglit in light cwntaine1.s. T h e \\.eight disti,il)ution of tlie d r y rwiduc is ~ i t ~ c ~ c ~inn tFipuix, c ~ l 1. 'I'h(, ~josiitioiio f thcx fii,*t masimrim i s in a vcyy good spiwiiicnt with that ( ~ i I r i i l : i t t d fi,oin datu in Figiiw 2b; S=4. 011 thc othi,t hand. the
I
mh of
I
0
0,2
a4
0.6 0.8 VOL. FRACTION OF BENZENE
VOL FRACTION OF BENZENE
Figure 3. ( a ) Diagram of R F vs. volume composition for the system cyclohexane 4- benzene/FA. ( b ) Same data, /?vs. .,I composition plot
--
R ~ I
----
-.-.
IogK
log K '
+
+ log K "
+
1904
ANALYTICAL CHEMISTRY
MMVERINE 3 4
0
2
4
6
8
10
FRACTION
Figure 4. Weight distribution curve after countercurrent distribution M o b i l e phase, 2 5 v./v. formamide
70 chloroform
in cyclohexane;
NP
16-transfer
stationary phose,
I
also be utilizrtl for the t.hoit.c. of suitatilc ellis for nonayuf'oll nO:I])olal~pha5.c fo For a more accwal(~eLstiniation of thc\ optimal solvent composition, it n-nuld be advantageous t o detrrinine the Imrtition coefficients in thr oihinuni solvent tein estimated from chroniatogral)hic data and introtluce an appropriate rorrection in the conilio,.ition of the mixed phase, if necessary.
CODEINE
LITERATURE CITED
( 1 ) Jusink, FmrioN
Figure
5.
Weight distribution curve after a 24-transfer run
M o b i l e phase, 23 v./v. formamide
70cyclohexane
each alkaloid in thi. contents of the e l t ~ n i t ~ nSt o . 0 . T h e weight distrihution of alkaloids is presented in Figure 5. A bin the former sj-stem an almost conil)lcte scparation of the model mixture \vas obtained, which was also confii,mcd ti)- paper cliromatographic~ anal!.& of the fractions. 130th alkaloid. orcurred only in fractions S o . 9 to 11, thc \wight of which i.i only a very small 1iai.t of the original mixture. l'he ohit it ion of thf, first niaximum is i n very good agreement with that calrulated from Figure 3b, A' = 5 . For tho other alkaloid, the niaximum ocrurrctl at a lower fraction number
in benzene;
I,., Folia Soc. Sei., Lukili~
(Poland), in press.
( 2 ) Jusiak, L., Soc.zewii'ski, E., \l.aksmundzki. A,. ~ l c t uPolon. Pharvi. 19.
stationary phase,
than exiiected, No. 16 instead of S o . 20 calculated from Figure 3b. This divergence must have tieen caused by nonfulfillnient of the assuni1)tions made in the theoretical treatment : nonlinearity of the partition isotherin, differentw between thc dynainir 1)artition coefficient in the chromatograi)hic ~)rorc+, and the equilibrium partition coefficients which o w u r in the cabcade processes, t,tc. Changes in the composition of the mixed nonpolar phase were in this rase much smaller as the difference of volatilities of cyclohexane and henzrne ip murh lo\vcr. The resulti of cxlwiinents indicate that paper chromatographic data may
(Polmd), in press. ( 1 0 ) \Vaksniundzki, h.,Soc.ze\\-i.'ski, J5.,
Continuous Separation by the Method of Thin Layer Chroma tog r a p hy S. TURINA, V. MARJANOVIC-KRAJOVAN, and
M. OBRADOVIC
lnstitufe for Inorganic and Analyfical Chemistry, University o f Zagreb, Yugoslavia
b A new method has been developed for the continuous separation of a mixture b y thin layer chromatography. Two different systems of solvents are fed from different sides to the thin layer spread on a triangular glass plate, while the mixture to b e separated i s introduced inear the apex of the triangular plate. The separated fractions leave the lolate at its base. 1he separation of iron and cobalt has been successfully carried out on this apparatus.
Figure 1. The principle of continuous thin layer chromatography
VOL. 36, NO. IO, SEPTEMBER 1 9 6 4
o
1905
