Document 1gzqgGVo3b5VNngx8r0Q78EXZ

January 15, 19^7 Mr. Allan L. Coleman Chief Industrial Hyglenlat Connecticut State peparfcmenfc of Health Hartford (1), Connecticut Dear Mr. Coleman: Your letter of January 8 to Dr. Kehoe and your questionnaire con cerning the analysis of chlorinated hydrocarbons have been turned over to me for reply* I find thatlcannot give you the information which you require in tabular form, but must do it In the form of & letter. This la so because circumstance determines the proper analytical approach. In our own toxicological studies on contaminated atmospheres we have used successfully both catalytic combustion and absorption methods of sampling, the sampling procedure adopted in this work being determined by the chemical nature of the contaminant and the avail ability of certain equipment. When the exposure Is to a known single compound, the absorption method of sampling gives consider able leeway In tbe choice of a method of final determination. Thus, it may be possible with samples collected by suitable absorption technique to determine the contaminant In question colorimetrlcally, by the degree of ultraviolet absorption or by the determination of chloride ion following either combustion or hydrolysis with suit able reagents. In the case of certain aliphatic chlorinated hydrocarbons, the colorimetric method based on tbe Fujlwara reaction la far more con venient than the combustion or hydrolysis method, and we have used this method successfully for the determination of carbon tetra chloride, chloroform, bromlnafced monochlorobutane, hexachlorobutadlene and triohloroacetonltrlle* It Is more than likely that many of the aliphatic chlorinated hydrocarbons In your H o t can be determined in the same fashion. Ithen properly carried out the colorimetric method is precise, very sensitive and rapid. In the case of tho determination of aromatic chlorinated hydro carbons, we would also prefer absorption methods which would then be followed preferably by ultraviolet absorption measurement, or, if this was not possible because of interference due to the ad mixture of compounds, by the determination of chloride ion follow ing hydrolysis with suitable reagents. r Mr. Allan I. Coleman January 15# 19V?# continued -2- From our own laboratory experience noted above ne have settled on the absorption method of sampling In the field since as indicated previously this gives us considerable leeway in choosing our final estimation procedure. .-On the whole we prefer to employ colori metric and ultraviolet absorption methods for the estimation of the contaminant and would employ combustion methods or hydrolytic tech niques only when the former are not feasible. 9 Outside of using the combustible material indicator we have had no experience with field instruments employing physical properties. We have not been called upon to identify chlorinated hydrocarbons in organic solvent mixtures and therefore we have not given this topic any thought. However, we would be interested in such pro cedures and trust that in time information which you are gathering could be made available to us. Very truly yours, J. Cholak JC:egm cc.s Dr. Robert A. Kehoe