each of monuron, diuron, and fenuron. Khile background peaks are fairly prominent in this curve, p-chloroaniline (PC.4), 3,4-dichloroaniline (DCA), and aniline (AS) can be satisfactorily measured a t the concentration levels present in this extract. ACKNOWLEDGMENT
The author is indebted to H. L. Pease for preparing many of the samples described in this paper, and
to be published. (5) Smith, D. H., Shigenaga, R. S., Soil Scz.. SOC. Am.. Proc. 25. 160 I1961 -~ ). (ti) Young, H. Y., GortnLr, K. A., .%SAL. CHEM.2 5 , 800 (1953). ( 7 ) Zq-eig, G., rlrcher, T. E., Rubenstein, D., J . Agr. Food Chem. 8 , 403 (1960). RECEIVEDfor review October 13, 1961. Accepted January 11, 1962. Presented in part .4CS Summer Analytical Symposium on Trace Analysis, Houston, Tex., June 1960. Division of Agricultural and Food Chemistry Meeting, 140th Meeting, ACS, Chicago, Ill., September 1961.
to G. J. Wallace, who assisted with the experimental work.
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LITERATURE CITED
K. E., Baker, H. &I., Levitsky, M.,Lowen, IT. K., J . -4gr. Food C h e m 2,476 (1954). (2) Coulson, L). M., Cavanagh, L. A., De Vries, J. E., li-alther, B., Ibid., 8, 399 (1960). (3) Kjrkland, J. J., hCS Suminer Symposium on Trace Analysis, Houston, Tex., June 1960. (4) Pease, H. L., J . Agr. Food Chem., (1) Bleidner,
Determination of Unreacted Monomers in Aqueous EmuIsions of Interpolymers SIR: The determination of residual, unreacted monomers in polymer latices is the subject of recent work using gas chromatographic techniques (1, 2 ) . In some cases, i t is sufficient to determine total hydrocarbons. I n others, because of produclt performance, i t is often necessary to measure not only the total volatiles but also the level of each of the coniponcmts. =Icrylonitrile, for example, is a semitosic compound LI hose coilcentration must be reported in the parts per million range. This problem e m be considered in two parts. The first is to separate the individual organic components from each other as well as the group from the aqueous matrix. The separation of aqueous matrix b y means of drying media has been already reported (1, 2 ) . The other problem is to detect the individual components at low level concentrations. To meet these needs, the gas chromatographic method using a hydrogen flame detector is proposed. The hydrogen flame detector is uniquely applicable in this case because i t is insmsitire to water. The Perkin-Elmer Vapor FInctometer Model 154 is used, n ith the addition of an auxiliary injection system in place of a gas-sampling loop. The injection system consists of a tube 3/8-inch i.d. by 3 inches long. fitted with the appropriate gas inlet, outlet, and rubber septum for hypodermic sample injection. The hydrogen flame detector used is similar to that designed by Beckman Instruments, Inc. The material used to demonstrate this method is a three-component interpolymer latex, containing approximately 44% solids. The latex is diluted quantitatively 1 to 10 with water, and 50 pl. of diluted latex is injected into the instrument b y means of a hypoder-
mic syringe. To obtain vaporization of the volatile components, the injection block is operated at a temperature of 140' C. The resulting gas chromatogram (Figure 1) indicates the potential of this method. Peak 2 represents the residual acrylonitrile present in the latex at 45 p.p.m. Also noted is the residual and unreacted styrene monomer peak 6 at a 0.12% concentration, and peak 9, 2-ethyl hexyl acrylate, a t a concentration of 0.67%. We find that a column of 10% stearaniidopropyldiniethyl - p - hydroxyethyl ammonium nitrate (American Cyanamid Corp.) is most suitable. The use of this column for the separation of polar and olefin-type compounds will be reported later.
1
0
1
,
,
,
1
10
5
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I
I
In addition to information on residual monomers, the chromatogram provides data concerning other impurities and additives which under certain circumstances could also be of importance in the latex performance. LITERATURE CITED
(1) Uroclslcy, J., Kunststofe 51, 20 (1Otil). (2) Nelsen, F. M.,Eggertsen, F. T., Holst, J. J., k A L . CHEX. 33, 1150 (1961).
PETER SHAPRA~ GEORGE C. CLAVER
Plastics Division Research Department Monsanto Chemical Co. Springfield, Mass. RECEIVED for review December 4, 19til. .4ccepted January 15, 1962.
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1536
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MINUTES
Figure 1.
Chromatogram of diluted latex
Time scale from 15 minutes has been reduced by a factor o f 5 Column. 1 0% stearamidopropyldimethyl-~-hydroxyethylammonium nitrate on Chromosorb W, 6 feet long, '/4 inch 0.d. Temperature. 100' C. Carrier gas and flow rate. He, 40 cc. p e r minute
VOL. 34, NO. 3, MARCH 1962
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