The negative ion icr spectra of SO,, HC1, HBr, BC13, BF3, PF5, SiF4, AsF5, SF6, and combinations thereof were studied at various electron energies and pressures in an effort to obtain evidence for ion-molecule reactions yielding halide ion adducts. Only primary negative ions were observed with pure samples except for the previously reported SiF=r, BFr, and AsF,-~and the additional species Si2F8~and B.Fr. Addition of SFe greatly enhanced halide adduct formation and was utilized in the reaction mixtures for all systems investigated. The relative order of fluoride ion affinity has been found to be: SF4, SF3• < SO,, HC1, AsF3 < SiF4 < BF3 < PF3 < BC13 < AsF3. Fluoride ion affinities of these compounds and the enthalpies of formation of the corresponding fluoroanions have been estimated.

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This paper describes laboratory comparisons of precision and accuracy of some widely used methods for the determination of lead in blood and for lead and cadmium on filters. With the exception of the tantalum boat atomic absorption technique, the methods studied were found to be rugged for a variety of minor procedural changes. Recovery of cadmium from spiked filters was quantitative over a wide range of dilutions and for a variety of instrumental readout and calculation combinations.

The analysis for sulfur-containing species such as sulfur dioxide, sulfur trioxide, and sulfates in the atmosphereboth ambient and workplace -