No abstract

cobalt, gallium, and tin, it has an advantage over the carrier distillation procedure, because certain elements forming highly refractive oxides, such as the rare earths, can be determined with a high degree of sensitivity.The simplicity of the ion exchange procedure makes it ideal for spectrographic purposes because the elemental contamination can be held to very low levels. The manipulations can be easily carried out in a glove box. The number of additives is held to a minimum.The visual comparison procedures used in the preceding work have already provided valuable information and were adequate for the present application. The desirability of extending the usefulness of the method through the increased accuracy of densitometric procedures is also recognized. These procedures have been applied and are being prepared for publication.It appears entirely possible to develop a method for plutonium using nitric acid exclusively except for the initial dissolution.However, hydrochloric acid prepared as described above had smaller amounts of the common impurities, such as calcium, magnesium, sodium, aluminum, and boron, than the nitric acid used. Consequently, hydrochloric acid was preferred for the determination of these elements. Furthermore, the division of the sample into hydrochloric and nitric acid fractions reduces the possibility of matrix effects in the excitation of an impure sample.In specific instances the ion exchange technique used in conjunction with conventional spectrographic methods may provide the means of extending the concentrational limits of detection another order of magnitude. ACKNOWLEDGMENTThe authors wish to express their appreciation to D. C. Stewart and . H. Studier for helpful discussions during the course of this work. They are also grateful to J. A. Goleb for the carrier distillation results of Table I. This paper is based on work performed under the auspices of the U. S. Atomic Energy Commission.

No abstract

Data are presented on the acute toxicity (mortality only) of the thermal degradation products of polymers obtained by two methods of degradation. One system utilized a slowly increasing temperature (5 degrees C/min) and gradual degradation of the polymer with the rats being exposed to degradation products as they were evolved. In this system the more toxic polymers included wool, polypropylene, poly(vinyl chloride), and urethane foam. The second system utilized conditions of rapid combustion and exposure of rats to the total products of combustion for a period of 4 hr. In this system the more toxic materials included red oak, cotton, acrylonitrile-butadiene-styrene (ABS), and styrene-acrylonitrile. It is of interest to note that the natural product wool is among the least toxic under these rapid combustion conditions and among the most toxic under slow pyrolysis conditions. Other materials also vary in the comparative toxicity of their thermal degradation products, depending upon the conditions of degradation and animal exposure. The two experimental techniques presented here may well represent the two extreme conditions of rapid combustion versus slow pyrolysis. Intermediate types of fire situations might be expected to result in relative acute toxicities somewhere between these two extremes. This report deals with acute toxicity on the basis of mortality data only and does not include other parameters of toxicity such as organ weights and histopathology.

A method for monitoring exposure to ethylenediamine (EDA) in the occupational environment is described. The EDA is adsorbed on activated silica gel, desorbed with 0.5 percent aqueous cupric chloride, and analyzed by gas chromatography using a 2 percent KOH on a Chromosorb 103 column. The method is sensitive to 200 micrograms/mL EDA and can detect 1.0 ppmv EDA in samples collected for 4.5 hours at a 300 cc per minute flow. The method has been evaluated in the laboratory and under plant conditions. Other amines do not interfere with the determination of EDA.