Replacement of Lead Peroxide in Carbon, Hydrogen Microdetermination

Abstract

The neocupferron titration curve illustrates the same mode of behavior, although somewhat less clearly. High-frequency titration of praseodymium chloride verifies the intermediate formation of the 1 to 1 complexes, MCup + + and M(NeoCup) + t. CONCLUSIONSCupferron and neocupferron seem to be excellent precipitating agents for the rare earth ions, provided that no interfeiing substances are present in the solution. Since cupferron and neocupferron are fairly general precipitating agents for many metal ions, it is obvious that they cannot compete with oxalic acid when the rare earth ions are to be separated from other impurities. However, in the absence of impurities and when only a small amount of rare earth is present in solution (2 to 50 mg.), the relatively large volume of precipitate and the ease with which it can be washed and filtered make the determination somewhat more accurate than the oxalate precipitation.Apparently, under precipitation conditions describe here, considerable amount of coprecipitation makes it impossible to determine accurately the amount of the rare earth present from the weight of the dried precipitate. However, ignition to the oxide is rapid and yields very satisfactory results. ACKNOWLEDGMENTThe assistance of George E. Knudson in obtaining the absorption spectra of the rare earth solutions is gratefully acknowledged.

OXYMERCURATION OF cis- AND trans-PROPENYLBENZENE

“…Found: C, 31.0; H, 3.42. This satisfactory analysis of a mercurial is typical of those carried out using a modification of the Pregl micro carbon-hydrogen determination (13) and is in contrast to the penultimate analysis reported in this paper. This latter analysis was carried out in the ordinary Pregl tube.…”

Ammonium Sulfamate as Substitute for Lead Peroxide in Microdetermination of Carbon and Hydrogen

“…Pooled variances (10) of the analytical values in Tables I and II are hydrogen 0.034 and carbon 0.026. The corresponding pooled variances of the analytical values for cyclonite, picric acid, and 2,4-dinitrophenylhydrazine [Table III, (3)] are hydrogen 0.003 and carbon 0.018. The accuracies of the analytical determinations using ammonium sulfamate or trishydroxylammonium phosphate (3) are not significantly different for either carbon or hydrogen.…”

Determination of Carbon and Hydrogen in Organic Fluorine Compounds

“…It is well known that lead peroxide, frequently used in combustion tube fillings to absorb oxides of nitrogen, is partially hydrated. Close control of the amounts of water produced by the sample and the volumes of carrier gases passed over the lead peroxide is necessary to maintain a steady state and to obtain quantitative transport of water to the absorption train (5,7,9). Thus, samples containing little or no hydrogen produce little or no water and dehydrate the lead peroxide, causing high hydrogen results (15).…”