a time-of-flight mass spectrometer (tof-ms) developed in our laboratory at isfahan university of technology is described here. the tof-ms instrument uses laser as the ionization source which provides an opportunity to investigate the ions formed in laser ablation or desorption. the tof-ms has an ionization chamber containing an accelerator and an ion lens to focus the ions into a one meter line...

In the present study, the high-resolution stable carbon ( 13 C/ 12 C) and oxygen ( 18 O/ 16 O) isotope ratio profiles in the wood of the mangrove Rhizophora mucronata Lam., a tropical tree species lacking distinct growth rings, were investigated. Variations of both isotope ratios revealed a remarkable annual cyclicity with lowest values occurring at the latewood/earlywood boundary (April–May) a...

Stable isotope analysis has become a powerful tool to study feeding ecology, water use or movement pattern in contemporary, historic and ancient species. Certain hair and teeth grow continuously, and when sampled longitudinally can provide temporally explicit information on dietary regime and movement pattern. In an initial trial, we analysed a tail sample of an Asiatic wild ass (Equus hemionus...

A procedure for Stable Isotope Dilution Analysis in molecular Mass Spectrometry which does not require a methodological calibration graph and can be applied in combination with minimal labelling has been evaluated. This alternative approach is based on the determination of the molar fractions for each pure isotope pattern (natural abundance or labelled) contributing to the isotope pattern obser...

The stable carbon isotope (13)C is used as a universal tracer in plant eco-physiology and studies of carbon exchange between vegetation and atmosphere. Photosynthesis fractionates against (13)CO(2) so that source sugars (photosynthates) are on average (13)C depleted by 20‰ compared with atmospheric CO(2). The carbon isotope distribution within sugars has been shown to be heterogeneous, with rel...

Alteration of the Allende meteorite caused shifts in oxygen isotope ratios along a single mass fractionation line. If alteration was caused by aqueous fluid, the pattern of oxygen isotope fractionation can be explained only by flow of reactive water down a temperature gradient. Down-temperature flow of aqueous fluid within planetesimals is sufficient to explain the mineralogical and oxygen isot...

Background: This study aimed to evaluate the reaction of organism of laboratory animals on deuterium-depleted drinking diet. To assess the cell energy metabolism, the effect of a liquid medium with different deuterium contents on isolated liver mitochondria of random bred rats and Wistar rats was studied. Methods: This experimental study on the effect of deuterium-depleted drinking water (DDW) ...

We present a method for determining the sum formula of metabolites solely from their mass and isotope pattern. Metabolites, such as sugars or lipids, participate in almost all cellular processes, but the majority still remains uncharacterized. Our input is a measured isotope pattern from a high resolution mass spectrometer, and we want to find those molecules that best match this pattern. Deter...

The metabolism of C ~4-1abeled pyruvate in normal and neoplastic tissue has been studied both in vitro (8, 10, 13, 14) and in vivo (3). Although the experiments of the Coris (6) and Warburg (1~) indicated a net production of lactate by tumors in vivo and in vitro, the metabolism of trace quantities of C14-1abeled pyruvate was not found to be significantly different in tumors and other tissues i...