of ethyl acrylate in the extractive distillation step is 10~070. Preparation of the calibration curves from distilled standards is recommended as a general procedure since recovery of many inoiioiners in the distillation step may not be complete. The sensitivity of the method for ethyl acrylate according to the procedure used for quality control analysis (0.5-pl. sample and a 10 to 1 attenuation ratio) is approximatldy 40 p.p.m. of nionomer. By injecting a 5-pi. sample and using a n attenusition ratio of 128 to I , 0.0002 gram of ethyl acrylate equivalent to 4 p.p.m. in a 50-gram sample, has been detected. Under the latter conditions, ben?#ene,present a,s an inipurity in reagent grade toluene, Iroduces a larger peak than ethyl acrylate, but the two peaks are completely separated. The precision of tlie method was demonstrated by mab:ing a series of I O determinations on a typical emulsion. Xri average value of 0.194yo ethyl acrylat,e was obtained with a standard deviation of f 0 . 0 1 6 . The column which we iised does not tli.;tinguish between ethyl acrylate and cthyl propionate, an impurity soinetinies found in ethj.1 acrylate. The two rnaterials have lieen separated in our laborstory, lioivrtver, on a liquid substrate of tetraethylene glycol diniethyl ether. Since ethyl acrylate is aln-ays the dominating odor in tlic ethyl acrylates t p w criiulaions iiivcstigatctl, thcrc
toluene at this temperature, but by temperature programming from 50" to 150" C., separate and symmetrical peaks for ethyl acrylate, toluene, and styrene were obtained. Acrylonitrile and ethyl acrylate \Iere determined simultaneously in a n exlwimental polymer by analyzing the emulsion under exactly the same conditions of distillation and chromatography used for the ethyl acrylate-stj rene copolymers. .icrylonitrile is allpreciably soluble in nater, but the satisfactory calibration curve obtained indicates that the partition coefficient favors the extraction of acrylonitrile into toluene. The method can be extended to other monomers by proper choice of naterimmiscible organic solvent, column, and instrument parameters. The method is l i m i t d , lionever, to monomers which can be readily extracted from nater.
TOLUENE
1
ETHYL ACRYLATE
LITERATURE L
x5
XI0
u_ 0
1
2
l
l
1
4
1
1
l
l
I
5
6
1
8
9
ml""1.t
Figure 1. Chromatogram of acrylate and internal standard
ethyl
\vas little interest in determining styrene. Styrene monomer is rwovered in the toluene layer and can be chromatographed and separated from the toluene a t approximately 1%" C. Ethyl acrylate is iiot q a r a t c t l fruin
CITED
(1) Brobst, I
