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Error propagation in normalization of stable isotope data: a Monte Carlo analysis
Author(s) -
Skrzypek Grzegorz,
Sadler Rohan,
Paul Debajyoti
Publication year - 2010
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.4684
Subject(s) - normalization (sociology) , isotope , propagation of uncertainty , monte carlo method , chemistry , isotope dilution , stable isotope ratio , statistics , mass spectrometry , analytical chemistry (journal) , algorithm , mathematics , chromatography , nuclear physics , physics , sociology , anthropology
A higher analytical precision of a stable isotope ratio mass spectrometer does not automatically guarantee accurate determination of the true isotope composition ( δ ‐value) of samples, since estimates of true δ ‐values are obtained from the normalization of raw isotope data. We performed both Monte Carlo simulations and laboratory experiments to investigate aspects of error propagation during the normalization of carbon stable isotope data. We found that increasing both the number of different reference standards and the number of repetitions of each of these standards reduces the normalization error. A 50% reduction in the normalization error can be achieved over the two‐point normalization by either analyzing two standards four times each, or four standards two times each. If the true δ ‐value of a sample is approximately known a priori , the normalization error may then be reduced through a targeted choice of locally optimal standards. However, the difference in improvement is minimal and, therefore, a more practical strategy is to use two or more standards covering the whole stable isotope scale. The selection of different sets of standards by different laboratories or for different batches of samples in the same laboratory may lead to significant differences in the normalized δ ‐values of the same samples, leading to inconsistent results. Hence, the same set of standards should always be used for a particular element and a particular stable isotope analytical technique. Copyright © 2010 John Wiley & Sons, Ltd.