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Serum calcium isotope ratios

Table IIB Calcium Isotope Ratios In Serum (Relative to Ca)... Table IIB Calcium Isotope Ratios In Serum (Relative to Ca)...
Isotopically enriched iron tablets have been used to study absorption of iron from nutritional sources. Iron is a very problematic element for ICP-MS in biological samples because there are significant interferences from Ar-based and Ca-based molecular ions. Vanhaecke et compared sector-field ICP-MS with a collision cell ICP-MS for the determination of iron isotopes in semm The problem exists mostly because typical levels of calciumin semm are approximately 50 times higher than those of iron. This study found that sector-field ICP-MS at a mass resolution of 3000 allows accurate determination of iron isotope ratios in human serum but only Fe/ Fe ratios could be determined with sufficient accuracy and precision using CO as a reaction gas with a DRC-ICP-MS. This was due to the DRC-ICP-MS not being able to correct for both the argon and calcium interferences. [Pg.390]

Fitzgerald et al,54 studied the monitoring of calcium metabolism in patients in the final stages of renal disease using serum by AMS after isotopic labelling with a 41 Ca radiotracer. The authors hypothesized that bone resorption can be studied directly by serial measurements of the 41Ca/Ca,otal ratio in serum after in vivo labelling of the calcium pool with 41 Ca.54... [Pg.347]

The intravenous administration of a second isotopic label can also be used to assess true absorption of the oral isotopic labels for elements that are excreted via the kidneys, such as calcium and magnesium. As in plasma appearance studies, the intravenous label serves as a reference dose. When the second label is infused or injected slowly following administration of the labeled test meal, both labels appear in parallel in serum/plasma. Some of the circulating labels, however, are excreted via the kidneys, during which the amount ratio of the two labels in blood should ideally be preserved. If this is so, a single spot urine sample can be used, at least in theory, to determine the amount ratio of the two labels in serum. As the intravenous dose is known, this ratio can then be converted into the amount of oral label absorbed. As for most stable isotope techniques, this method was originally developed for radiotracers [31] and adapted for stable isotopes in the 1980s [32]. [Pg.447]


See other pages where Serum calcium isotope ratios is mentioned: [Pg.19]    [Pg.223]    [Pg.447]    [Pg.459]    [Pg.460]    [Pg.470]   
See also in sourсe #XX -- [ Pg.20 ]




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