V O L U M E 26, NO. 7, J U L Y 1 9 5 4
1173
Precision of Method W h e n Applied to Soils and Rocks. To demonstrate the precision of the method when applied to soils and rocks, four determinations of antimony were made a t different times on seven soil samples and two rock samples. The absorbancy of blanks in each run was zero. I n fact, identical readings were obtained on the samples when either the pure solvent or the blank was used in the null cell. For each sample the highest, lowest, and mean value as well as the standard deviations are shown in Table V.
Table VI.
satisfactory. The results obtained under field conditions or in temporary quarters are sufficiently accurate to indicate and define areas of antimony mineralization. hloreover, the method is short and simple enough to permit relatively unskilled workers to determine trace amounts of antimony in 20 or more samples of soils during an 8-hour day. ACKNOWLEDGMENT
The authors are grateful to H. E. Hawkes and Vance Kennedv of the U. S. Geological Survey for assistance in collecting the samples.
Determination in Laboratory and Field of Antimony in Idaho Soils Sample N o . 1
1 2 4
2 3 4
5 6
7 8 9 10 11
LITERATURE CITED
Antimony, P.P.M. Laboratory Field’
2~. 5
34 41 70 140 135 350 260
Cannon, H. L., A m . J . Sci., 2 5 0 , 7 3 5 (1952). Clarke, F. W., U. S. Geol. Survey, Bull. 770, 423 (1924). Clarke, S. G., AnaLysf,5 3 , 3 7 3 (1928). Edwards, F. C., and Voigt, A. F.,. ~ N A L .CHEM.,21, 1204 (1949) Eegriwe, E., 2. anal. Chem., 70, 400 (1927). Frederick, W.G., IND. ENG.CHEM.,ANAL.ED., 13, 922 (1941). Goldschmidt, 1‘. hl., Skrifter A’orske Videnskaps-Akad. Oslo, I . Mat.-Naturv. KZ.,KO.4 , 99 (1937). Hawkes, H. E., Econ. Geol., 44, 706 (1949). Hillebrand, W. F., and Lundell, G. E. F., “Applied Inorganic Analysis,” 2nd ed., p. 283, Kew York, John Wiley & Sons,
0.5 3 8 30 40 40 75 112 ~~
160
350 350
1953.
I n the range covered by the data in Table V, the precision is well within the requirements set forth by Youden (19). The standard deviation of the soils varies from 0.5 to 1 p.p.m. and about 68%three out of four-of the values obtained on each sample (soils and rocks) is within 1 standard deviation of the mean value. As the method is proposed for field as well as routine laboratory work, a comparison of results obtained in the field and laboratory is appropriate. Cuts from 11 soil samples analyzed for antimony in the field were brought into the laboratory and antimony determinations were made under more ideal conditions. ilbsorbancies of the isopropyl ether solutions of the antimony-rhodamine B compound were measured instrumentally, and the quantities of antimony were determined from a previously established standard curve. The results obtained in the field and in the laboratory are shown in Table VI. The agreement between field and laboratory determinations is
Huff, L. C., Econ. Geol.. 47,517 (1952). hIcChesney, E. W.,IND.ENG.CHEM.,ANAL. ED., 18, 146 (1946).
hlaren, T. H., Bull. Johns Hopkins Hosp., 77, 338 (1946). Maren, T . H., ANAL.CHEM..19, 487 (1947). Rankama, Kalervo, and Sahama, Th. G., “Geochemistry,” p. 738, Chicago, University of Chicago Press, 1950. Sandell, E. R., “Colorimetric Determination of Traces of Metals,” 2nd ed., pp. 165, 167, New York, Interscience Publishers, 1950. Webster, S. H., and Fairhall, L. T., J . Ind. Hug. Toxicol., 27, 183 (1945).
West, P. W., and Hamilton, W. C.,
; ~ N A L . CHEM.,24,
1025
(1952).
Willard, H. H., and Diehl, Harvey, “Advanced Quantitative .I\nalysis,” p. 346, Kew York, D. Van Nostrand Co., 1943. Youden, W. J., “Statistical hfethods for Chemists,” p. 12, S e w York. .John Wiley & Sons, 1951. Young. Philena. AN.AI.. CHEM., 24, 152 (1952). RECEIVED for review September 1 4 , 1953, Accepted
April 14. 1054.
Determination of Sesamin, Sesamolin, and Sesamol MORTON BEROZA Entomology Research Branch, Agricultural Research Service,
The determination of sesamin and sesamolin, pyrethrin synergists found in sesame oil, is of importance in the insecticide field. Existing procedures for their determination may sometimes be in error. -4method for the determination of sesamin, based on its separation in pure form by chromatography on silicic acid, is described. Solutions of ethyl acetate in 2,2,4-trimethylpentane are used to develop the chromatogram and the sesamin in the effluent is detected and identified by means of its ultraviolet absorption. Sesamolin and sesamol determined by the method of Suarez et al. gave less color than anticipated. I t is recommended that a solution of known concentration be run under identical conditions as the unknown, so that the concentration of the unknown may be based on the color developed by known. Chromatographic studies indicate that sesamolin is the only compound, exclusive of sesamol, that gives the Villavecchia color reaction.
U. S. Department o f Agriculture, Beltsville, Md The chromatographic procedure for sesamin, although time-consuming, is accurate, reproducible, and specific, The proposed modification of the sesamolin and sesamol procedures eliminates interferences found in the previous method.
S
ESAME oil, obtained from the seed of Sesamum indicum (L.), increases the insecticidal potency of pyrethrins ( 7 ) .
One of the constituents of the oil responsible for this activity was found by Haller et al. (8, 9) to be sesamin. More recently Beroza ( 2 ) found that sesamolin, another constituent of sesame oil, is a much more potent synergist than sesamin and, although present in lesser amount, it usually accounts for most of the synergistic activity of sesame oil with pyrethrins. The determination of both constituents is therefore of importance in the insecticide field. 1Iethodp for the determination of sesamin and ~esaniolinin
1174
ANALYTICAL CHEMISTRY
sesame oil and in commercial sesame oil concentrates have been published ( 4 , 5 ,10). Sesamin is determined, after the extraction of sesamol with alkali, from the total absorption of the oil a t its ultraviolet maximum (about 288 mp) minus a background correction and minus the absorbance due to sesamolin. The background correction is based on the assumption that it is roughly linear and is the arithmetic mean of the minimum absorbance a t about 255 mp and the absorbance a t about 320 mp, a point at which sesamin and sesamolin contribute practically no absorbance. Sesamolin is determined by a modification of the Villavecchia test ( I O ) . I n the application of this determination ( I O ) to various sesame oils and concentrates, difficulties were encountered. In one oil the ultraviolet maximum was found a t 283 mp and the minimum a t 260 mp. A background correction in this case would call for an absorbance reading a t 306 mp, a point a t which sesamolin contributes significant absorbance. Such results indicated interference in the method. Furthermore, the absorbance reading at 260 mp was sufficiently large to indicate appreciable interference. The absorbance of materials other than sesamin and sesamolin in the 255- to 320-mp range makes the background correction less reliable. Furthermore, any error in the sesamolin determination will affect the sesamin result. The determination of sesamin may therefore be subject to doubt. Another determination for sesamin has been devised. By this procedure sesamin is separated in practically pure form by chromatography on silicic acid. The column is developed with solutions of ethyl acetate in iso-octane, and the sesaniin in the effluent is detected and identified by means of its ultraviolet absorption ( 1 ) . The results obtained by this method are in good agreement with those obtained by the spectrophotometric procedure when the spectrum of the sample shows little interference-that is, its spectrum (less sesamol) approvimatw those of sesamin and sesamolin. Hen-ever, in the presence of foreign absorbance, the ultraviolet method often gave much higher results. For the determination of sesamolin a sample of the pure compound, melting point 94", was prepared by chromatography. The author &-as unable to obtain the intensity of color obtained by the previous workers for sesamol or its equivalent intensity of color from sesamolin (1/2.68 of that developed by sesamol). A further point was investigated. Sesamolin is known to give the Villavecchia test, but it vi-as not certain that i t is the only compound (excluding sesamol) in the oil that gives this color reaction. Evidence has now been collected that it is the only compound that gives this color. REAGENTS
2,2,4-Trimethylpentane (iso-octane), pure grade. Phillips Petroleum Co., Bartlesville, Okla. Distill before use. Ethyl acetate, N.F. absolute. Chloroform, U.S.P. Distill before use. Silicic acid, reagent grade. hferck & Co., Inc., Rahway, N. J. The following solutions of ethyl acetate in iso-octane (volume) are needed for each analysis: 100 ml. of 15%, 2000 to 2500 ml. of 3.574, and 550 ml. of 8%. EQUIPMENT AND APPARATUS
All spectrophotometric measurements were made on a Beckman Model D U quartz spectrophotometer using silica cuvettes 1.0 om. square. The chromatographic setup consists of a column, a reservoir, an adapter, and an air supply. The column is a glass tube, 2.3 cm. in inside diameter and 42 cm. long, with a sintered-glass disk sealed just above a constriction a t the lower end to a 2-cm. length of 7-mm. tubing. A female 24/40 joint is sealed t o the upper end of the column. The reservoir is a 2-liter separatory funnel fitted with a male 24/40 joint a t its lower end and a female 24/40 joint a t its upper end. The adapter is made of 1-cm. glass tubing attached to a 24/40 joint. I t fits into the top of the reservoir or the column and delivers air pressure to the apparatus. Any suitable air-pressure regulator may be used.
PROCEDURE FOR SESAMIN DETERMINATION
Preparation of Column. Weigh out 80 grams of silicic acid into a mortar and mix with sufficient iso-octane to form a freeflowing slurry. Pour the slurry into the column (it need not be quantitative) and wash down the sides of the column with more solvent. During the addition hold the column a t an angle so as not to entrap air. Fasten the adapter directly to the top of the column and apply an air pressure of 3 pounds per square inch. Tap the sides of the column to ensure uniform settling of the adsorbent. Release the air pressure when the solvent level is just above the top of the silicic acid. Never permit the column to run dry. Finally, prewash the column with 100 nil. of 15% ethyl acetate in iso-octane, followed by 75 nil. of isooctane. Discard the effluent. The column is now ready for use. Operation of Column. Introduce onto the top of the colunin an 8- to 10-gram weighed sample of sesame oil dissolved in 25 nil. of iso-octane. Wash the oil solution into the hdsorbent with several small portions of iso-octane followed by 75 ml. of isooctane. If a concentrate is being analyzed, dissolve a 0.5- to I .Ogram weighed sample in several m]. of chloroform and dilute with iso-octane just short of turbidity. Wash the solution into the adsorbent with at least three small portions of 1to 2 chloroforniiso-octane followed by 75 ml. of iso-octane. Watch the column closely when adding the sample, particularly if i t is introduced in chloroform, as cracks in the adsorbent may develop. They are usually easy to detect, and a flat glass rod 1 cm. in diameter may be used to tamp down the adsorbent lightly to seal the cracks. Wash the rod with solvent before removal. Fill the column and reservoir with 3.5% of ethyl acetate in iso-octane and attach the reservoir to the column. Open the stopcock (it must not contain grease but be lubricated with solvent) and fasten the adapter to the top of the funnel. A4pp!y sufficient air pressure (3 to 4 pounds per square inch) to maintain the flow rate a t about 400 ml. per hour. Detection of Sesamin Fraction. The important point in the chromatography is to determine when sesamin first appears in the effluent. Read the absorbance of the efRuent a t 280, 288, and 300 mp, with the slit width set a t the narrowest limit or maintained constant for each wave length. Such readings are unnecessary during the first 1500 ml. of effluent, as sesamin will not be eluted. Between 1300 and 1900 ml. of sesamolin is usually eluted. Under the conditions outlined the sesamolin fraction is usually contaminated with other ultraviolet-absorbing materials. For Instance, sesamol is eluted with sesamolin and sometimes an ultraviolet-absorbing material precedes and separates incompletely from it. The sesamolin fraction is detected by its 280/288/300 mp absorbance ratio (approximate) of 0.9/1.0/0.48. Save the sesamolin fraction and its forerun for solvent recovery. Prior to the appearance of sesamin all or almost all of the sesamolin has passed off the column and the absorbance a t 288 mp (peak) drops to a low value. Sesamin is recognized by its 280/ 288/300 mp absorbance ratio of 0.9/1.0/0.14, or more simply its 288/300 mp ratio of 7.0, compared to 2.1 for sesamolin. Thus, the first appearance of the sesamin fraction is detected by a rise in the 288/300 mp ratio. As soon as this ratio reaches 2.25, change the eluant to 8% ethyl acetate in iso-octane, and start collecting the sesamin fraction. A volume of 550 ml. of this eluant is sufficient to elute all of the sesamin. Crystallization of Sesamin. Evaporate the effluent containing the sesamin on a steam bath a t reduced pressure to about 20 ml., transfer the residue to a 100-ml. long-necked flask with chloroform, add 2 glass beads, and evaporate to dryness a t reduced pressure by swirling the contents of the flask on a warniwater bath. Take up the residue with a medicine-dropper pipet in a minimum of chloroform (3 to 5 ml.) and filter; receive the filtrate in a 15 X 150 mm. test tube. Evaporate the filtrate under reduced pressure by rotating the test tube in a warniwater bath. To be sure no chloroform remains, place the test tube in a 60' water bath for 0.5 hour under reduced pressure from a water aspirator. Add 1 ml. of iso-octane and mix the contents of the test tube in a steam bath by swirling for a minute. Stopper the tube and put in the ice box a t 5' for several hours. By means of a medicine-dropper pipet with a 2-mm. opening transfer the sesamin that crystallizes out of solution to a weighed microfilter funnel having a fritted disk (such as Pyrex Catalog No. 36290, medium porosity), and wash the test tube and precipitate three times with 0.5-ml. portions of cold iso-octane. Dry a t 105', cool in a desiccator, and weigh. The weight gai? is due to sesamin, which almost always melts a t or above 120 . Pure sesamin melts a t 122.5'. Sometimes the sesamin forms crystals too large to be picked
V O L U M E 26, NO. 7, J U L Y 1 9 5 4 up by the pipet, I n this case break the crystals with a small stirring rod and then transfer. The transfer of sesamin is never quantitative as about 1 mg. of crystals usually adheres to the test tube, pipet, and stirring rod. Take up these residual crystals in chloroform and make up to 10 ml. in a graduate; then dilute to 50 ml. with iso-octane. Measure the absorbance a t 288 mp against a 1 to 4 chloroform-iso-octane solution. Determine the amount of sesamin from the following formula: absorbance a t 288 mp X 50 LIg. of sesamin = 23.03 This weight of sesamin plus that of the precipitate is the total weight of sesamin in the sample. A column may be run in one day and the sesamin recovered the next day while another column is being run. However, it has been found most convenient to set up a column in the afternoon and adjust the air pressure so that about 1500 ml. drips through overnight. Most of the chromatography is therefore completed by morning. The use of a fraction collector also saves much time. Adsorbent. Satisfactory separations were obtained with three lots of silicic acid under the conditions described. It is possible that the silicic acid obtained may be very active (such a n adsorbent may be prepared by heating a t 110") and will cause extremely slow elution of the compounds. The elution may be hastened by increasing the concentration of ethyl acetate in the iso-octane. The adsorbent may be used repeatedly, but the elution volume becomes greater as it is prewashed with the higher concentrations of absolute ethyl acetate in iso-octane, probably owing to abstraction of water (11). For predictable elution volumes a sufficient amount of adsorbent for all analyses should be obtained and the adsorbent discarded after each analysis. This procedure also eliminates the danger of contamination from a previous run. Recovery of Solvent. The solvent recovered from the chromatography by distillation may be re-used after its ethyl acetate content has been determined and adjusted, by the addition of either iso-octane or ethyl acetate. The ethyl acetate concentration is determined by refluxing 5 ml. of the solution with 10 ml. of 0.5N alcoholic potassium hydroxide for 1 hour, washing down the condenser with 15 to 20 ml. of water, and titrating the residual alkali nith standardized 0.5N hydrochloric acid. A blank is run on iso-octane only. The concentration is calculated from the following formula:
% ethyl acetate (v./v.) = 9.77 X normality of acid X (iso-octane titration-solvent titration) ml. of solvent The small amount of chloroform used in introducing sesamin concentrates does not interfere with future analyses. SESAMOLIN AND SESA-MOL DETERAMINATIONS
Procedure. The sesamolin and sesamol were determined as described by Suarez et al. ( I O ) , except that :a solution of known concentration was run a t the same time under identical conditions and the absorbance was measured exactly 1 or 2 hours after shaking was started. The concentration of the unknown was based on the color developed by the known. Preparation of Sesamolin. Budowski ( 6 ) has discussed the preparation of sesamolin and has given a means of isolating it from sesame oil but not from sesamin concentrates. The following method has proved useful for the preparation of small quantities of sesamolin from sesamin concentrates. hlix 400 grams of concentrate with 1 liter of Skellysolve B and place in an ice box a t 0" for 24 hours. Filter off the precipitate and wash with cold Skellysolve B. Dissolve the precipitate in chloroform and filter with the aid of Hyflo Super-cel. Evaporate the filtrate completely and crystallize the residue from a minimum of hot alcohol. Sesamin begins to come out of solution almost immediately. When the solution has cooled to 35O, filter off the precipitate. This material melts near 120" and is therefore practically pure sesamin. As the solution cools, more
1175 material precipitates and its melting point is lower than that of the first batch. A final 2rop of crystals is obtained by concentrating and cooling t o 0 . The higher melting crystals may be freed of much sesamin by another alcohol crystallization. The lower melting materials, 75" to loo", are rich in sesamolin, but may still contain much sesamin. Chromatograph these materials in a column (5.5 X 31 em.) containing 300 grams of silicic acid. Introduce 1.5 to 2.0 grams in chloroform-iso-octane solution and develop the column as above with 3.5% of ethyl acetate in iso-octane. Collect the sesamolin, which starts off a t about 6000 ml., as long as the 288/300 mp ratio remains less than 2.2. Collect separately the next fraction, the absorbance ratio of which is between 2.2 and 3.5. The residue of this fraction is rich in sesamolin and may be saved for future recovery of sesamolin. The remaining material on the column is mostly sesamin and may be discarded. Evaporate the sesamolin fraction t o a small volume and sesamolin will crystallize out. Filter and recrystallize from chloroform-iso-octane. The sesamolin melts a t 94" and is pure as judged by optical rotation, ultraviolet spectrum, and elementary analysis. RESULTS OF DETERMINATIONS ON SESAME OILS AND SESAMIN CONCENTRATES
Various sesame oils and sesamin concentrates were tested, some commercially prepared and some extracted by the author from seed. One of the commercial oils, A, was a crude oil prepared by the Regal Chemical Go., Brooklyn, N. Y . Another crude oil, B, and a sesamin concentrate, L, that was obtained by cold alcohol extraction of the crude oil, were prepared by the Pacific Vegetable Oil Corp., San Francisco, Calif. Another oil, C, was a commercial alkali-refined sample. Two samples of oil, D and E, from seed of the sesame variety K-IO, were grown a t Plainview, Tex., in 1951, but the seed from which E was obtained was harvested after being damaged by frost and the oil was rancid. Oils from seeds of the varieties Venezuela 51, F, and Y6, G, both grown a t College Station, and from K-10, H, grown a t Lubbock, Tex., were grown in 1952. These oils were extracted from the seed by the author; the oil content was 48 to 53% (no moisture correction). Concentrates I, J, and K were supplied by the Southern Regional Research Laboratory. Results of these tests are given in Table I. DISCUSSION
Sesamin Determination. The agreement between the chromatographic and the spectrophotometric procedures for sesamin determinations on oils extracted by the author from the seed is good. The results on the sesamin concentrates are in only fair agreement. On two of the three commercial samples of crude sesame oil these methods give widely different results. The two samples had shifted absorption maxima (at 282 and 283 mp) and minima (at 260 mp). For each sample the minimum absorbance was more than half the maximum absorbance, indicating the presence of much foreign absorption and therefore interference with the spectrophotometric method.
Table I.
Material
Sesamol, Sesamolin, and Sesamin in Sesame Oils and Sesamin Concentrates Spectrophotometric Method, % Sesamol Sesamolin Sessmin
Sesamin, Chromatographic Method, %
Sesame oils
A B C D E F G H
0.012 0.0014 0.0045 0.00032 0.00032 0.00038 0.0190 0.00019
Sesamin concentrates
0.209 0.3035 0.0059 0.358 0.152 0.436 0.335 0.343
1.225 0.535 1.12 0.553 0.094 1.125 0.476 0.405
0.904, 0.904.0.9013 0.510, 0.514 0.452, 0,425 0.507, 0.514 0.066, 0.074,0.060 1.08, 1.10 0.462, 0.458 0.380. 0.377
1176
I n several experiments to check the recovery of sesamin bJ7 chromatography, 98 to 99% of the added amounts were recovered. In an experiment to determine the completeness of precipitation of sesamin, a longer column was used to ensure a complete separation of sesamolin from sesamin. The mother liquor remaining after precipitation of the sesamin was tested for synergism with pyrethrins and found to have practically no activity. The chromatographic method is specific, because sesamin is isolated in practically pure form. For verification of its identity a melting point and a mixed melting point may be run, or its physical properties, such as optical rotation and ultraviolet spectrum (5), may be checked. The spectrophotometric method depends upon a deduction for sesamolin and an assumed background correction. The present analysis depends upon no assumptions or deduction. Although a t least two chromatographic columns may be run simultaneously, the present type of analysis is more time-consuming than the spectrophotometric method. For this reason the author would recommend the spectrophotometric method for analyses on oils and concentrates which do not show much interference in the ultraviolet. Oils extracted from the seed a t room temperature showed very IittIe interference and analyses on their oils by both methods were in good agreement. The sample that gave the poorest agreement between the spectrophotometric and the chromatographic analyses was the commercial alkali-refined oil. It was thought that alkali isomerization, which may have taken place during refining, may have caused the interference. No such interference was observed after following a typical refining procedure-that is, neutralizing with 15% excess of sodium hydroxide, maintaining for 1 hour a t 70°, filtering, washing four times with hot water, and drying with sodium sulfate. I t is possible that a higher refining temperature, a greater excess of alkali, or both, or even hot pressing of the oil from the seed, may be responsible for the interference encountered in the spectrophotometric method. I n any event, the present procedure does not appear to be affected by commercial processing. Re-ent work ha4 indicated that the interference in the ultraviolet method is associated with rancidity of the oil. Some of the oils used in the above analyses were 6 years old. Sesamolin and Sesamol Determinations. Samples of pure sesamol [kindly supplied by the Southern Regional Research Laboratory, melting point 63-64.2", also synthesized ( 3 ) . Caution should be exercised in this synthesis, as it may be explosive] developed less color than anticipated from previous work (IO), as did equivalent quantities (molar) of sesamolin. This color is therefore influenced by some uncontrolled factors. Suarez et al. state that the absorbance of bound sesamol (sesamolin) should be checked 50 to 75 minutes after shaking of the sample was started. In this time interval the absorbance changed lOy0 or more, However, if the concentration of the unknown is based on the color developed by a known amount of
A N A L Y T I C A L CHEMISTRY sesamolin run a t the same time with the same reagents and the absorbances of both are measured a t the same time, there is practically no difference in results, even if the absorbance is measured 1, 2, or 3 hours after the start of shaking. For instance, an oil was found to contain 0.417, 0.421, and 0.421% of sesamolin when the absorbance was determined after a I-, 2-, and 3-hour period. It is possible that the delayed as well as the lesser color development may result from reagent effects. Temperature markedly affects the rate of color development. Rather than try to control these variables, it is much simpler t o run a known along with the regular analyses. In all the tests for sesamol and sesamolin reported in Table I, the concentration of the unknown was based on the color developed by a known. I n chromatographic experiments, not reported here, sesame oil was divided into 15 fractions and each fraction was tested for sesamolin ( I O ) . Only those fractions associated with the sesamolin zone gave color. Less than 3% of the total color produced by the oil was found in the remaining fractions. In another experiment the sesamolin fraction was separated and evaporated to dryness. Iso-octane was added to the residue and sesamolin crystallized out a t 0". These crystals accounted for about 90% of the sesamolin in the oil. Analysis of the mother liquor showed an additional 8% of sesamolin. The fact that the color reaction is associated only with the sesamolin zone indicates that sesamolin is the only material producing the color reaction. ACKNOWLEDGMENT
The author is indebted to F. G. Dollear, Southern Regional Research Laboratory, and to Murray L. Kinman, U. S. Bureau of Plant Industry, Soils, and Agricultural Engineering, College Station, Tex., for supplying most of the oils and concentrates used in this work. LITERATURE CITED
(I) Beroza, XI., A N ~ LCHEM., . 22, 1507 (1950). (2) Beroza, I f . , J . A m . Oil Chemists' Soc., in press.
(3) Boeseken, J., Cohen, W.D., and Kip, C. J., Rec. Irav. chim., 55, 815 (1936). (4) Budowski, P., O'Connor, R. T., and Field, E. T., J . Anz. Oil Chemists' Soc., 27, 307 (1950) (5) Ibid.,28,51 (1951). (6) Budowski, P., Ibid., 27, 264 (1950). (7) Eagleson, C., U. S. Patent 2,202,145 (Uay 28, 1940). (8) Haller, H. L., LaForge, F. B., and Sullivan, W. N., J . Econ. Entomol., 35,247 (1942). (9) Haller, H. L., XIcGovran, E. R., Goodhue, L. D., and Sullivan, W. N., J . Org. Chern., 7, 183 (1942). (10) Suarez, C. C., O'Connor, R. T., Field, E. T., and Bickford, W. G., ANAL.CHEM.,24, 668 (1952). (11) Trueblood, K. K . , and Malrnberg, E. W., Ibid.,21, 1055 (1949). RECEIVED for revieiv November 14, 1953. Accepted April 19, 1954.
