Reevaluation of the preparation of organic compounds for the mass spectrometric analysis for oxygen-18

Abstract

the bulk would suggest. The same is true for potassium, which was not previously known to be occluded in hard gold electroplates. ACKNOWLEDGMENTThe authors would like to acknowledge Irene Payne for performing all of the densitometry and some of the sectioning of substrates. We would also like to thank A. Tartaglia for substrate sectioning and etching, T. Palumbo for the electroplating, and L. Blitzer for the atomic absorption analyses. The reduction of massive amounts of data was made relatively easy by a computer program prepared by T. Loomis, to whom the authors are also indebted.

Oxygen-18 measurement by continuous flow pyrolysis/isotope ratio mass spectrometry of vegetable oils

“…For instance, the determination of the carbon isotope ratio ( 13 C/ 12 C) by isotope ratio mass spectrometry (IRMS) and of (D/H) i by site-specific natural isotopic fractionation NMR (SNIF-NMR) permit the detection of additional exogenous sugar in fruit juice or wine. [1][2][3] Access to the D/H and 18 O/ 16 O ratios in water samples allows the detection of watering of beverages. [4][5][6][7][8] The 18 O/ 16 O isotope ratio of water from plants or of natural compounds (e.g.…”

“…[1][2][3] Access to the D/H and 18 O/ 16 O ratios in water samples allows the detection of watering of beverages. [4][5][6][7][8] The 18 O/ 16 O isotope ratio of water from plants or of natural compounds (e.g. carbohydrates) gives interesting information about the environmental climatic conditions during their formation.…”

“…In the past, the most common method used for the determination of the 18 O/ 16 O ratio of organic matter was first described by Rittenberg and Ponticorvo, 10 who carried out pyrolysis of samples at 500°C in sealed quartz tubes using HgCl 2 as catalyst, resulting in the production of HCl, CO 2 and CO (the CO being converted into CO 2 with I 2 O 5 ). This method has been successfully modified and improved to enhance the accuracy and precision, in particular by the conversion of CO to CO 2 using a high-voltage discharge, and also by the use of different catalysts and more efficient HCl traps.…”

“…Different carbon catalysts (natural and synthetic diamond, charcoal, Ni/C, Pt/C) have been investigated to achieve better conversion yields at lower temperatures. 11,[22][23][24][25] A few of these studies were directed at the determination of the 18 O/ 16 O ratio. Taylor and Chen, 23 for instance, reported the capability of a Pt/C catalyst to reduce the temperature of carbon reduction from 1200 to 900°C.…”

“…25 The above-described methods are laborious and time consuming, and are used by only a few laboratories which developed their expertise in the field generally for the purposes of fundamental research in biology, geochemistry or physiology. In contrast, recently a few European laboratories, specialized in the isotopic analysis of food products, have developed their own on-line sample preparation methods for the determination of the 18 O/ 16 O ratio of organic compounds. Some have already published promising results which indicate the possibility of the determination of this parameter in routine isotopic analysis of various products.…”