After 2004 and 2008 (Vols. 378/2 and 390/2) this is the third issue of Analytical and Bioanalytical Chemistry to contain papers on new developments and applications in isotope ratio measurements. Whereas Klaus Heumann was guest editor for the two previous special issues, in this issue Torsten Schmidt joins him as guest editor for the first time. His involvement with this collection of papers st...

RECEIVED for review February 21, 1978. Accepted June 19, 1978. NMR spectra since two distinct peaks (6 -3.38, 3.78 ppm) caused by these protons are observed in CDCA vs. only one peak (6 -3.45 ppm) caused by the same protons in UDCA. T h e fingerprint region of the spectrum (6 1-2.5 ppm) and the relative position of the CIS methyl peak with respect to tha t of the doublet caused by the Cpl methy...

High-resolution spectra of the CN B2 summation operator +-X2 summation operator + (0,0) band at 390 nanometers yield isotopic ratios for comets C/1995 O1 (Hale-Bopp) and C/2000 WM1 (LINEAR) as follows: 165 +/- 40 and 115 +/- 20 for 12C/13C, 140 +/- 35 and 140 +/- 30 for 14N/15N. Our N isotopic measurements are lower than the terrestrial 14N/15N = 272 and the ratio for Hale-Bopp from measurement...

Instrumentation and methods exist for highly precise analyses of the stable-isotopic composition of organic compounds separated by GC. The general approach combines a conventional GC, a chemical reaction interface, and a specialized isotope-ratio mass spectrometer (IRMS). Most existing GC hardware and methods are amenable to isotope-ratio detection. The interface continuously and quantitatively...

Folate metabolism, which is responsible for one-carbon transfer reactions in critical cellular processes including thymidine biosynthesis, is among the most important targets of antibiotic and anticancer drugs. Analysis of intracellular folates is complicated by three different types of folate modification: oxidation/reduction, methylation, and polyglutamylation. Here we present a method for qu...

We demonstrate the first successful application of infrared laser spectrometry to the accurate, simultaneous determination of the relative H/H, O/O, and O/O isotope abundance ratios in natural water. The method uses a narrow line width color center laser to record the direct absorption spectrum of low-pressure gas-phase water samples (presently 10 μl liquid) in the 3 μm spectral region. The pre...

We have detected circumstellar absorption lines of the CN and CN Violet and Red System in the spectrum of the post-AGB star HD 56126. From a synthetic spectrum analysis, we derive a Doppler broadening parameter of b = 0.51 ± 0.04 km s, CN/CN= 38±2, and a lower limit of 2000 on CN/CN and CN/CN. A simple chemical model has been computed of the circumstellar shell surrounding HD 56126 that takes i...