Concentration of N15 by Chemical Methods

Abstract

A study has been made on the application of chemical exchange reactions to the problem of the concentration of the nitrogen isotope of atomic weight 15. We have investigated the exchange reactions involving ammonia as the gas phase and solutions of ammonia in water and alcohol, and of ammonium nitrate and ammonium sulfate in water as the liquid phase. The apparatus used consists of an efficient type of fractionation column previously described. It is found that the exchange reaction between ammonium nitrate solution and ammonia is probably the best of all of these for this purpose, except that ammonium nitrate solutions corrode our steel column so badly that their use is impractical in the present apparatus. The exchange between ammonium sulfate solutions and ammonia gas is shown to be more satisfactory for the purpose than any of the other combinations, and has been used to secure a 6½-fold increased concentration of N15. Substantial amounts of nitrogen containing high concentrations of N15 have been produced and these together with the efficient mass-spectrometer method of analysis make possible a wide variety of studies.

Effects of Cross Linking on the Chromatographic Nitrogen Isotope Separation

“…The sampled fractions of effluent were subjected to concentration analysis of ammonium ion by YokogawaHokusin IC-100 ion chromatography analyzer (Tokyo, Japan). Nitrogen isotopic abundance ratios of 14 N and 15 N in the samples were measured by two mass spectrometers ESCO EMD-05S double focusing mass spectrometer for gas samples and IsoPrime EA mass spectrometer, which accepts solid samples such as NH 4 Cl. When ESCO EDM-05 was used, the samples collected in the chemical form of NH 4 Cl were converted to N 2 samples by KBrO solutions prior to the analysis by mass spectrometry and the isotopic abundance of 15 N was calculated from the ratio of the peak height.…”

“…Nitrogen isotope separation by ion exchange chromatography has been studied since Urey et al made experiments between gaseous ammonia and ammonium salts in aqueous solution using a cation exchange resin [4]. Separation and concentration of a stable isotope from an isotopic mixture with natural occurrence is a very complex problem and usually, the isotopic separation coefficients of natural abundance are very low.…”

Stable isotopes in the diagnosis and treatment of inherited hyperammonemia

“…Nitrogen-15 was identified and isolated in 1937 [1], only 5 years after discovery of the urea cycle [2]. This coincidence facilitated pathbreaking research in nitrogen metabolism.…”

“…The rationale for developing [1][2][3][4][5][6][7][8][9][10][11][12][13] C] acetate as a tracer is that, although the 15 NH 3 probe enabled effective monitoring of the response to NCG [39] the taste of solutions of NH 4 Cl is objectionable to most subjects and administration of ammonium salts is risky in the patient who is prone to hyperammonemia. Using [1-13 C] acetate as a probe neutralizes these problems, but is not without potential complications.…”

Nitrogen Isotope Separation by Ion Exchange Chromatography

“…The separation of the nitrogen isotope has been studied since Urey et al first succeeded in concentration of the nitrogen isotope of atomic weight 15 by using chemical exchange between ammonia gas and aqueous solutions of ammonium salts [21]. In their work, the …”