Apparatus for Continuous Extraction of Nonpolar Compounds from Water Applied to Determination of Chlorinated Pesticides and Intermediates LLOYD KAHN and COOPER H. WAYMAN
U. S.
Geological Survey, Denver Federal Center, Denver, Colo.
b A continuous, multichamber liquidliquid extractor, with interncl solvent recycle, for the extraction of nonpolar contaminants from natural waters is described. The multichamber arrangement makes it possible to judge the completeness of extraction of a given component from the aqueous stream. Recoveries as high as 100% are obtained by applying the apparatus to the extraction of the pesticides aldrin, dieldrin, and endrin and their manufacturing intermediates.
P
Only one laboratory apparatus with internal recovery and recycle for the continuous liquid-liquid estraction of organic compounds from a a t e r ia reported in the literature ( 5 ) : a singlechamber unit, developed for the eatraction of trace organics from sea water. The present paper describes a multichamber apparatus, each chamber of which is capable of efficiently extracting low concentrations of nonpolar organic compounds from water. The efficiency of extraction of each chamber and, therefore, the completeness of estraction are readily judged from the concentration of a particular component in successive chambers of the apparatus. This feature is especially useful in the estraction of the newer pesticides, for which the distribution coefficient between water and the respective organic solvents is not known. The present apparatus was tested by extracting several chlorinated hydrocarbon pesticides and their manufacturing intermediates from water. As the apparatus may be used for the extraction of extremely large water samples, it is possible to isolate, purify,
per billion concentrations of chlorinated hydrocarbon pesticides in natural waters have been reported ( 1 ) to cause the destruction of fish. The need for determining trace amounts of these pesticides in ground water and surface water is, therefore, evident. Two methods which have been utilized extensively for the estraction of pesticides from water are adsorption on activated carbon with subsequent desorption by organic solvents (3) and liquid-liquid estraction (4).The former method was studied by Rosen and Middleton (S),who obtained low recoveries of benzene hesachloride; chlordan; 1,l)ltrichloro-2,2-bis(p-chlorophenyl)ethane (DDT); 1,2,3,4,10,10-hexachloro-l~4,4a, 5,8,8a - hexahydro - 1,4endo - exo-5,8 - dimethanonaphthalene (aldrin) ; 2,2-bis( p - chlorophenyl) - 1,l - dichloroethane (TDE, D D D ) ; and 1,2,3,4,10,10-hexachloro-6,7-epoxy-l,4,4~,5,6,7,8,8a - octahydro - l ,4 - endo - endo - 5,s-dimethanonaphthalene (endrin) by carbon adsorption and subsequent desorption with chloroform. Teasley and Cos (4), utilizing liquidliquid ext,raction, extracted 1-liter water samples batchwise and determined chlorinated hydrocarbons by microcoulometric gas chromatography. The quantities estracted were too small, however, for infrared analysis. Of the two procedures, the liquid-liquid estraction method was preferred by the authors, as previous esperience indicated that some of the pesticides and their intermediates are not stable on activated carbon. I t is possible that Figure 1 . Detailed drawing of exthis effect contributed to the low results traction chamber obtained by Rosen and Middleton ( 3 ) . ARTS
1340
ANALYTICAL CHEMISTRY
and identify very minute concentrations of organic pollutants in water. The lower limit of detectability of a particular component in water is limited only by the build-up in the estract of interfering, nonremovable impurities. EXPERIMENTAL
Materials. Aldrin (99+% 1,2,3,4, 10,lO - hexachloro - 1,4,4a,5,8,8ahesahydro - 1,4 - endo - exo - 3,8dimethanonaphthalene). Dieldrin (99+% 1,2,3,4,10,10-hexachloro - 6,7 - epoxy - 1,4,4~,5,6,7,8,8aoctahydro - 1,4 - endo - exo - 5,s - dimethanonaphthalene). Endrin (99 % 1,2,3,4,1O,lO-hexachloro - 6,7 - epoxy - 1,4,4a,5,6,7,8,8aoctahydro - 1,4 - en,do - endo - 5,8dimethanonaphthalene) . Isodrin (approximately 99% 1,2,3,4, 10,lO - hexachloro - 1,4,4a,5,8,8a- hexahydro - 1,4 - endo - endo - 5 3 - dimethanonaphthalene). Compound 773 (>95% 1,2,3,4,5,7,7heptachlor0 - bicyclo [2.2.l]hept-2-ene). Compound 601 (approximately 92% 1,2,3,4,7,7 - hexachlorobicyclo [2.2.1] hepta-1 $-diene). Sample A. Approximately 20 liters of a water sample were obtained a t the Rocky Mountain Alrsenal,Denver, Colo., of the effluent waste stream of a manufacturing facility which produces the insecticides aldrin, dieldrin, and endrin, among others. The stream was, therefore, expected to contain these insecticides and their intermediates. The sample was filtered to remove suspended solids prior to extraction. Sample B. hpproximately 135 liters were obtained from a well, located on the water table, about 100 feet north and downgradient from the lake fed by the stream from which sample was taken. Because suspended solids were not visible, t,his sample was not filtered. Apparatus. detailed drawing of one of the estraction chambers is shown in Figure 1 . The chamber consists of a 1-liter Erlenmeyer flask, A , provided with a 10-mm. gl inlet, B , near the bottom and a 10-nini. glass tub? outlet: C, lorated about 1 2 em. above the bottom of the flask. The Erlfnmeyer flask is ronnected by 24 -10 T joints to a 7 5 " three-way connecting tube, D , which in turn is connwted, by 24 40 T joints, at the top to a 5-inch long 24.40 to 29;42
+
A\
T joint adapter, E , and a t the side to a 105" two-nay connlacting tube, F , which is attached to a 500-ml. roundbottomed flask, G. The top of adapter E is fitted with a 29 42 T A411ihncondenser, H , below \vhich is suspended, in the bulb, I , of the adapter, a funnel tube, J , which extends to near the bottom of the Erlenmeyer flask. ;1 magnetic stirring bar, K , lying on the bottom of the Erlenmeyer flask, is actuated by magnetic stirrer L. Flask G is heated with an electric heating mantle, M) which is controlled by the Variac, S. Procedure. L I Q U I D - L I Q U I D EXTRACTION. Three extraction chambers, identics1 to t h a t $;howl in Figure 1, are connected in series with each of the 500-ml. round-hottompd flasks, G, being charged with about 300 ml. of petroleum ether (33.7' t o 57.7' C. boiling point). Each of t h e three Erlenmeyer flasks, ,4, is charged with distilled or unpolluted potable water to a level about 1 inch rtbove the outlet tubes, C. The water lwel is controlled by raising or lowering :in inverted glass T-tube, connected in series with the last extraction chambe)-,before starting the magnetic stirrer. The Variac is adjusted between 60 m d 90 volts to obtain a strong reflux of the solvent, which is condensed and flows from the condenser into the mouth of the funnel tube, J , through which it passes to near the bottom of the aqueous stream, where it is dispersed 13y the magnetic stirring bar, K , and after passing through the water, the extractate overflow into the round-bottomed flask, G, from which the solvent is redistilled. A peristaltic pump feed:) the extraction chambers from a water-sample reservoir a t a rate of 0.5 to 1.0 liter per hour. Recycle solvent flow rates of 481, 670, 900, and 1100 ml. per hour are obtained a t Variac settings of 60, 70, 80, and 90 volts, respectively. Thus, a t an aqueous stream residence time of 45 minutes and an 8O-voIt Variac setting, the apparatus maintains a 1 to 1 solvent-aqueous phase ratio per extraction chamber. No difficult,v in phase separation is encountered, if the aqueous phase entering the apparatus is free from insoluble impurities, and the organic solvent rapidly rises above the aqueous phase. When all of the ,sample has been pumped from t'he water-sample reservoir, approximately 3 liters of unpolluted potable or distilled water are added to the reservoir and pumped a t the same rate into t,he apparatus to ensure that all of the sample has been extracted in each of .:he three extraction chambers. -4ftei- cooling, flasks G are disconnected from the apparatus, and the solvent, is evaporated, or diluted with additional petr'deum ether, to contain 0.2 to 1.5 nanograms of the respective chlorinated hydrocarbons per microliter of solution. as required for gas chromatographic analysis, and dried with anhydrous sodium sulfate.
A
54
52
50
48
41
I
Figure 2.
B
Gas cnromatograms of sample A A.
8.
TIME IN MINUTES
Gas Chromatography. The columns, conditions, and retention d a t a for compounds 601 and 773, aldrin, isodrin, dieldrin, and endrin are described in Tables I and I1 and Figure 2. The columns were prepared by adding the appropriate amount of substrate in chloroform or benzene t o hexamethyldisilazane-treated Chromosorb W and evaporating the solvent
Table I.
ColSolid umn support A Hexamethyldisilizanetreated Chromosorb W B Hexamethyldisilizanetreated Chromosorb W
Mesh size 100/120
45/60
Column A Column B
with agitation on a steam bath. The columns were conditioned at 300' C. overnight with a slow nitrogen flow prior to their use. Quantitative data for the individual components were obtained from a calibration curve depicting peak heights vs. concentrations in the range 0.2 to 1.5 nanograms. Column Chromatography and Infrared Analysis. The unused portions of the solutions prepared for gas chromatographic analysis are conibined and evaporated. Oxygenated compounds-indicated by the strong infrared bands near 1720 and 1260 em.-*, for example (Figure 3)-almost completely obscure the infrared bands of the chlorinated hydrocarbon compounds. To remove these and ot? er interfering substances, the residue from
Gas Chromatographic Data
Liquid phase Apiezon L
SE-30 silicone gum
Liq- Column uid, length, I.D., % ft. mm. 5 3 4
5
4
4
Column Column tzm material C?" Stainless 190 steel
Stainless steel
165
Operating conditions. Inlet pressure. 23 p.s.i.g. Carrier gas. Xitrogen Detector. Electron affinity Detector temperature. 200' C. Injection port temperature. 185" C.
VOL. 36, NO. 7, JUNE 1964
1341
Figure 3. A. 8. C. D.
Infrared spectra
Compound 601 Compound 773 Sample B prior to column chromatographlc cleanup Sample B after column chromatographlc cleanup
vated alumina column (2 cm. in diameter and 10 em. high, Baymal colloidal alumina). The analyzates are eluted with 120 ml. of chloroform, evaporated
the evaporation of the gas chromatographic solutions is dissolved in 2 ml. of chloroform and applied t o the top of a chloroform-washed and wetted acti-
and analyzed with an infrared spectrophotometer, such as Perkin-Elmer Model 221G. RESULTS A N D DISCUSSION
Table (I. Extraction Efficiency of Apparatus for Chlorinated Hydrocarbon Pesticides and Intermediates
Extraction solvent. 38.7" to 57.7" C. boiling petroleurn ether in each chamber Residence timer per chamber. 45 niinutes Sample volume. Sample A, 20 liters Sample B, 135 liters Concentration, p.p.b. Compound Con2pj)und 601 Il.3 Aldrin Isodrin Dieldrin Endrin Sample A
w,
68
180 4 5 1 7 9i
w 2
w3 % E
1 0 0 6 98
230 6 7 3 5 96
160 5 8 2 3 95
340 5 5 4 7 97
Nil
Nil Si1 Xi1
-9
I
911 ?;I1
(100)
Sample B 0 8
WI
w2
0 2 0 04
0 06 88
5; E
83
Si1 Si1 Si1
Si1
Nil
Si1
Xi1 Si1
Calculation of extraction efficiency C
E
=
w,x
____ Ti', + It;
i~hamber),and H', . . evt rartion chambers. ~~
~~
1342
100
+ IV3 . . ,
JV,'
lL',t are concentrations of a particular component in successive
~
e
where %cEis extraction efficiency (of first evtraction
ANALYTICAL CHEMISTRY
The use of the apparatus allowed extraction of the nonpolar chlorinated hydrocarbons from water with an extraction efficiency of as much as 100% (Table 11). The calculation is based upon data obtained by either two or three extraction chambers. In c a w where efficiencies approach 90 to 1007G, the use of additional extraction chambers could not alter the extraction efficiency significantly. Table I describes the conditions and columns used for the gas chroniatographic analysis. Column I3 was used in all the analyses except for endrin. The column is characterized by its good resolution of the individual compounds and by its retention of the other impurities beyond the elution titneb of compound 601, compound 7 3 . aldrin, isodrin, dieldrin, and endrin, thus remol-ing interference with their anal? -4s endrin decomposes ( 2 ) and ita decomposition product is eluted very late from this column. it was not detectable
a t t h e I-nanogram level, and was, therefore, analyzed on column h The inii)uritie. were eluted ac a group in 42 to 57 minutes on column 13. Colu~nn X way not utilized €or the complete beciuie of its poorer reiolution of the indi! idual m a l j zates. Chromatogram. of .ampl> 1 on the t a o column- arc presented in Figure 2. Infrared spectra of compound< 601 and 7 7 3 and iainple I , . before and after chromatographic cleaiiup, are shown in Figure 3. The wnilarity of the purified iam1)le T3 .pectruni and that of ('om1)ound 601 ic ob\ i o u c . but cornliound 7 7 3 I. identified by it. band. a t 1200, 1060, 970. and 662 cnl-'. Inyiection of thrl .pcctra point< out the need for chromatographic cleanuli prior to infrared analy-is. The extraction ( l a t i of samples containing t n o concentrtttion level- of the chlorinated compound. are cornpled in l'ahle 11. I t I\ evidcnt from the data on iamplc A that the extraction efficiencj of the fir5t chamber not exactly reproduced in the othrv chamber\ For e\aini)li., baied on the 97% e\traction effici?nC) obtained for C!oTll]J(Juild 601 by the fir-t e\tractioii clianiber, one nould e\pcct to find 6 0 anti 0 2 1) p.b of coinpound 601, re.pecti\ ~ l y In , the iccond and third e\traction chamber.
The deviation between these and the experimental values probably i p caused by a combination of analytical errors and differences in the estraction efficiency of the respective estraction chambers. These deviations are minor and do not affect the data significantly. A possihle esplanation of the rclatively high values, based upon estraction efficiency, obtained by the third chamber in the case of samlile X and ])robably by the second chamber in the case of sample 1% is a low level analytical interference which becomes significant a t low concentration values. This phenomenon would also esplain the low extraction efficiency obtained in the est'raction of sample 1%. Although the apparatus was limited to the use of only one extraction solvent in these esperimeiits, it can be made much more versatile by the use of different solvents in the estraction chambers and/or by treating the aqueous stream as it passes between chambers. For esample, a basic aqueous stream may be estracted with a nonpolar solvent, such as hexane, in the first estraction chamber and with a more polar solvent, sucah as cthtlr, in the second estraction chamber. Tho stream may then be treattd, for esample, with HCl in passing into the third extraction
chamber, convert'ing organic acid salts to t'heir respective acids, to be est,racted in the nest extraction chamber by an appropriate solvent. The use of such an extraction sequence would extract, \vit,hin limits, compounds according to their structural and,'or chemical characteristics. ACKNOWLEDGMENT
The cooperation of the authorities at, the Rocky Mountain hrsenal in obtaining the saniples, and of Shell Chemical Co., which furnished the reference samples, is gratefully acknowledged. The figures in the paper were prepared by John E. Robertson. LITERATURE CITED
(1) Henderson, C., Pickering, Q. H., Tarzwell, C. M.j Trans. A m . Fisheries Soc. 88,23 (19%). ( 2 ) Phillips, 11. I].> Pollard, G. E , $ Soloway, S. B., J . Agr. Food Chem. 10, 217 (1962). ( 3 ) Rose'n, A. A., Middleton, F. hf., A N A L .CHEM.31, 1729 (1959). (4) Teasley, J. I., Cox, W. S., .I. .4m. U.'ater Irorks .4ssoc. 5 5 , 109.11 (1963). ( 5 ) N'erner, A . E., m'aldichuk, Jlicaliael, AkS.kI,.CHEM. 34, 1674 (1962j. I ~ E C E I ~ EforL )review Xovember 18! 1063. Awept,ed llarch 4, 1964. Publication authorized by the I)irect,or, [ - , S. Geological Survey, Rashingt.on, I). C.
The Determination of dl- and meso-Dibromosuccinic Acids in Aqueous Solutions RAYMOND ANNlNCl and DAVID J. MANZO' Department of Chemistry, Canisius College, Buffalo,
b
A rapid procedure i s described for the analysis of mixtures of dl- and meso-dibromosuccinic acids. The concentration of the acids i s determined polarographically and compared to the amount remaining after 60 minutes in sodium hydroxisde at 25" C. Since only the dl isomer reacts quantitatively during this interval, the final limiting current can b e related directly to the original con'centration of the meso isomer. The concentration of the dl isomer is obtained b y difference.
A.
~II:THOI) was
d w i i ~ dfor the analysis of dilute solutions of dl- and n m o dibromosuc.cinic acids. The polar ogral)hica behavior of the acids has been rqmrtcd ( 2 ) hut, cnfortunately, the half-\vavc~potcntialq (of t,he two isomers UI'C not, sriffiriently wi)arated to allondirccir i)ol:iro,grapliic analy.sii. King and E'efcr (4)h a r e dcveloprd a kinetic method for the a n a l p i of thew two
N. Y.
compounds which is based on the observation that the d l isomer in acid solihon eliminates hydrogen bromide nine time? faster than the meso isomer. .is is the case with many kinetic procedures which do not involve large differences in rate constants, the method is quite lengthy, involves considerable operator time, and its accuracy is questionable es1)ecially when the differtmce in concentration of the two acids is large. I t is quite possible that the method could be improved by determining the total roncentration of the acids directly (polarographic analysis) instead of from a difference titration of the reaction mixture, and using the .single point nwthod of Lee and Kolthoff ( 6 ) . l'he >ubjcct of this paper is an altwnate and inorr satisfactory solution which involves increasing the difference in the rates of dehydrohalogenation as \wll as the ahsolute value of the rate constant.;. This is accomplished by rca d i n g the acids with cxcess base.
I-nder t'he condit'iorw selected, the rll isomer reacts quantitatively in 60 minute? while the'coiicentration of the meso isomer does not, change by more than 1% relative. However, 'a large positive salt effect is observed from these reactions. If the dibioniosuccinic. acids are dissolved in a solution of high ionic strength, a kinetic ~iroportionalityconstant for the rneso iqomer is determined in the sanie niati' EXPERIMENTAL
Reagents. meso - Dibromosuccinic acid (m-DuSAi)wa7 prepared by the addition of bromine to fumaric acid ( 7 ) . .ifter recry~tallizationfrom 50-50 acctone-i )ctroleum hesane, the nrotlurt melted a t 254"-255' C.; reported, 255-6" c'. ( 6 ) . 1 Present address, Chemistrv Department, Kansas State I-niverqitv. 31anhattan, Kan
VOL. 36, NO. 7, JUNE 1964
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