The calibration of measurements of the isotope amount ratio using a log-linear regression method with multicollector-inductively coupled plasma mass spectrometry (MC-ICPMS) is the latest development in isotope amount ratio metrology. This calibration method, however, is often met with criticism. In this work, we evaluate the robustness of this calibration strategy wherein measurements of antimo...

Fibers are often found at crime scenes and current methods can determine the chemical composition and color of the fiber as well as physical characteristics. Unless the fiber contains DNA, there is no way to compare a fiber found at a crime scene with fibers found in a suspect’s possession. This study aims to determine if isotope ratio mass spectrometry (IRMS) can be used to add an additional l...

Isotope effects are one of the most powerful kinetic tools for determining enzyme mechanisms. There are three methods of measurement. First, one can compare reciprocal plots with labeled and unlabeled substrates. The ratio of the slopes is the isotope effect on V/K, and the ratio of the vertical intercepts is the isotope effect on V(max). This is the only way to determine V(max) isotope effects...

The mechanism of L-ribulose 5-phosphate 4-epimerase of Aerobacfer aerogenes has been investigated by determining the kinetic isotope effect (KT/KH) for the epimerization of D-[4-T]xylulose 5-phosphate in the presence of D-[l-14C]xylulose 5-phosphate. The ratio of T:14C was determined for the isolated L-ribulose derived from aliquots of an epimerization reaction mixture during its progress towar...

The U-Th radioactive disequilibrium measurements with Multi-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS) were applied to a coral reference; JCp-1 distributed by the Geological Survey of Japan to evaluate homogeneity of the standard material. The two times of standard deviations (2SDs) of [U/U]isotope ratio, [ U/U]isotope ratio, U abundance, [ 230Th/ Th]isotope ratio, and T...

The isotope ratio of each of the light elements preserves individual information on the origin and history of organic natural compounds. Therefore, a multi-element isotope ratio analysis is the most efficient means for the origin and authenticity assignment of food, and also for the solution of various problems in ecology, archaeology and criminology. Due to the extraordinary relative abundance...