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It is not possible to measure the decay profile vs time as this is too long so the average number of disintegrations /time interval can be counted instead. From a consideration of the distribution of radioactive events the mean number of events in time $t$ is $M=N_0(1-e^{-kt})$ where $k$ is the decay constant and $N_0$ the initial number of atoms. For small ...


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There are a couple reasons this could be happening. The most interesting possibility: isotope effects during ion fragmentation You are performing LC-MS/MS, i.e., your mass spectrometer is chemically reacting the estradiol and estradiol-$d_5$ with gas molecules in the collision cell of the instrument. This process, known as CID or collisionally induced ...


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Isotopes differ in mass. Otherwise the same molecules but with the different mass have the different mean speed. The different speed means the different molecular collision rate. The different collision rate means the different kinetic constants. There are some indirect effects of different isotop mass on the kinetics, but these are much smaller than the ...


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