Magnesium tracer studies

Two methods that have been used in tracer studies with are neutron activation analysis CNAA) and EIMS, mass spectrometry of a volatile chelate with electron impact ionization C15>19,20). Neither technique can match TIMS in accuracy or precision, but both may offer greater sample throughput. Until more precise techniques become more generally available, research utilizing stable metal isotopes will remain limited to the conditions imposed by the analytical facilities at hand. As will be shown below, research with stable magnesium isotopes to date, has had to be tailored to the limitations of available analytical techniques ... 

The use of radioactive magnesium in tracer studies indicates that the magnesium present in food is poorly absorbed from the alimentary canal in some cases only 50 g/kg of the herbage magnesium can be utilised by the ruminant. AVhy this is so in ruminants is not known. Since adult animals have only very small readily available reserves of body magnesium, they are dependent upon a regular dietary supply. 

Becker, J.S., Fiillner, K., Seeling, U.D., Fornalczyk, G., and Kuhn, A.J. (2008) Measuring magnesium, calcium and potassium isotope ratios using ICP-QMS with an octopole collision cell in tracer studies of nutrient uptake and translocation in plants. Anal. Bioanal. Chem., 390, 571-578. 

Magnesium oxide has been investigated by Robertson and by Henney and Jones. Surface diffusion was identified as the dominant mechanism of transport in both of these studies. The activation energies appeared excessive for this interpretation. In the reevaluation of these data it was shown that interpretation as volume diffusion produced = 0.02 exp (—70,000/i 7, which is in agreement with the tracer and mass spectrometer results compiled by Harrop in which the mean activation energy for Mg and O migration is 70,500 cal/mole. 

The use of stable isotopes as tracers in clinical studies is becoming more commonplace. Human metabolism studies have been reported with enriched Mg and Mg measuring plasma, faecal and urine samples. In another study using Mg, the absorption of magnesium was seen to increase when certain fatty acids were also administered. Enriched boron stable isotopes have also been determined in rat urine and faeces to establish excretion pathways and found that... 

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