Premium
Calculation of stable isotope enrichment for tracer kinetic procedures
Author(s) -
Buckley Wayne T.,
Huckin Stuart N.,
Eigendorf Guenter K.
Publication year - 1985
Publication title -
biomedical mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0306-042X
DOI - 10.1002/bms.1200120102
Subject(s) - tracer , isotope , chemistry , kinetic energy , yield (engineering) , residual , stable isotope ratio , biological system , mathematics , thermodynamics , physics , algorithm , quantum mechanics , biology , nuclear physics
The choice of method of expressing isotopic enrichment in tracer kinetic experiments utilizing stable isotopes was found to affect the calculation of tracee pool size and half‐life. The most commonly used definition, the difference between enriched and natural abundance, i.e. atom percent excess, was found to result in significant error in model systems when the dose of tracer was 10% of the pool size. Errors in determining first‐order rate constants of efflux and in pool sizes decreased with decreasing ratio of tracer to tracee. Error in determining pool size increased with longer ‘sampling’ periods, while error in determining the rate constant increased with shorter sampling periods. Of three less frequently used expressions of isotopic enrichment two were found to yield the exact answers in model systems. The correct expression of isotopic enrichment were linear functions of the quantity of tracer in the system. A practical example demonstrated the effect of choice of expression of enrichment on estimates of whole body copper pool size and turnover in dairy cattle.