Evaluation of an Automatic Nitrogen Analyzer for Tractable and Refractory Compounds.

Abstract

If the acidity of the solution is too high, the amine is also protonated to a great extent and cannot add to the protonated aldehyde. If the acid concentration is too low, not enough of the aldehyde is protonated to cause a significant rate of addition of the amine.Samples of n-butylamine mixed with equimolar quantities of di-n-butylamine, tri-n-butylamine, and ammonia were titrated according to this procedure, and no interference due to the presence of these added bases was noticed. The results of the titration of the above mixtures were all within two standard deviations of the mean of the results of n-butylamine alone.Repeated attempts were made to titrate primary aliphatic amines in the presence of primary aromatic amines without success. Although the aromatic amines do not react appreciably with %ethylhexanal under the reaction conditions employed for the titration, the intrinsic ultraviolet absorbance of the aromatic amines a t 305 mp causes the absorbance of the solution being titrated to be so great that the relative change in absorbance during titration is very small. A number of aromatic aldehydes were tried as titrants, but none of these reacted rapidly enough with the aliphatic amines to make a practical titration possible.Crotonaldehyde, Lvhose carbonyl absorption peak is a t 325 mp instead of 295 mM, was also tried as a titrant, but unfortunately crotonaldehyde reacts to a significant extent with many aromatic amines while reacting only slowly with most aliphatic amines. Thus, the procedure reported can tolerate the presence of only a small amount of an aromatic amine or any other substance whose intrinsic absorbance at 305 mp is high.

Direct Dumas Determination of 30 to 1000 Parts per Million of Nitrogen in Oils.

“…However, if the furnace temperatures are too high other undesirable gases are produced. Sternglanz and Kollig (4) found that CO2 dissociates to CO at 800°C. in the presence of copper oxide.…”

Using geometric simulation software ‘GASP’ to model conformational flexibility in a family of zinc metal–organic frameworks

“…The nitrogen values of the elemental analysis were slightly lower than expected, which we attributed to known issue of incomplete oxidation affecting heterocyclic nitrogen species such as H 3 cbt. 19 Interconversion between the two unique solvates by suspending samples of 1 or 2 in either neat DMF or DMSO proved unsuccessful, and similarly 3 could not be accessed by suspending 1 in water (ESI: † Fig. S6).…”

Effects of the burrowing mayfly, Hexagenia, on nitrogen and sulfur fractions in lake sediment microcosms

“…An ion selective electrode was used to determine ammonia concentration (Allen 1974). Total N was determined by the Dumas method with a Coleman" nitrogen analyzer (Sternglanz & Kollig 1962). Sulfate was determined using the barium chloranilate procedure (Johnson & Henderson 1979), and total sulfur was found by the method of Steinbergs et al (1972).…”