Isotope Ratio Mass Spectrometric Method for the On-line Determination of Oxygen-18 in Organic

• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: oxygen-18; organic matter; biological samples; on-line determination; isotope ratio mass spectrometry; Greenland; GISP; Ice Sheet
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.468.3549; http://www.es.ucsc.edu/~pkoch/EART_229/10-0111 Fractionation/GEAR/Koziet 97 JMS 32-103.pdf

A method for the on-line determination of oxygen-18, at a naturally occurring level, in organic material is present-ed. After pyrolysis of the samples to form carbon monoxide, which is performed at 1300 ÄC in a vitreous carbon tube, the pyrolysis products are transported by a stream of helium gas. Using an open split, a small part of the effluent is transferred to the ion source of an isotope ratio mass spectrometer. The ratio is obtained from a measurement of the ion current intensities at m/z 30 and 28 (12C 18O and 12C 16O). The method was tested with the secondary water standard GISP (Greenland Ice Sheet Precipitation) and the carbonate standard NBS 19. The values obtained were and vs. VSMOW (Vienna Standard Mean Ocean Water) (IAEA referenceÔ24.8 & 27.3& values are and vs. VSMOW). The potential of the method was demonstrated by measuring theÔ24.8 & 28.7& 18O content of samples of beet and cane sucrose and also samples of vanillin extracted from vanilla pods or of synthetic origin.