Accelorator mass spectrometry for dating

One additional advantage of acceleration is that the ‘stripping process’ disassociates all molecular species with the result that carbon isotopes can be isolated, and contamination minimized.

AMS Phase 0 micro-dosing involves administering very tiny single doses of an investigational compound to humans before extensive testing in animals with the goal of culling early those compounds with problematic bioavailability or pharmacokinetics.

C atoms are required for an accurate AMS measurement, this represents a million-fold sensitivity enhancement compared to scintillation-counter detection.

Unlike the conventional organic mass spectrometry analyses described previously, AMS measures not molecules or their structural fragments, but the negatively charged , followed by its reduction to carbon (graphite).

By comparing this with modern levels of activity (1890 wood corrected for decay to AD 1950) and using the measured half-life, it becomes possible to calculate a date for the death of the sample.

It follows from this that any material which is composed of carbon may be dated.

For example, shell, in constant contact with more recent atmospheric carbon, will generally yield young dates; conversely a shell artifact deposited in older limestone sediments will obtain a much older date than its actual death.

These reservoir effects are in part mitigated by the use of various calibration algorithms, such as the CALIB (When a radiocarbon lab returns a date from a sample such as 5568 BP, it does not mean that it dates to 3619 BC, because the true half-life of radiocarbon is 5730 years, and, more importantly, the proportion of radiocarbon in the atmosphere has varied through time, as discussed above.

Micro-doses are specifically selected to not have pharmacological effects.The convention calls for reporting the provenience of the sample, the laboratory number, the radiocarbon age, and then the calibrated (in this case dendrocalibrated) age at one or two standard deviations (note that most of these dates yielded multiple intercepts).The calibration method used and any further contextual information should also be supplied.Micro-dosing studies have the potential to identify some of these failures early, thus avoiding wasted time and money in extensive animal testing.

Traditional comprehensive animal testing, building to first-in-human exposure of an investigational compound, costs

Traditional comprehensive animal testing, building to first-in-human exposure of an investigational compound, costs $1.5–3.0 million, and requires more than 18 months to complete.

By the late 1970s a number of researchers discovered that when accelerating sample atoms in the form of ions to much higher energies in particle accelerators, a much smaller sample was required to derive confident dates—in most cases only milligrams instead of tens of grams for scintillation counting.

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Traditional comprehensive animal testing, building to first-in-human exposure of an investigational compound, costs $1.5–3.0 million, and requires more than 18 months to complete.By the late 1970s a number of researchers discovered that when accelerating sample atoms in the form of ions to much higher energies in particle accelerators, a much smaller sample was required to derive confident dates—in most cases only milligrams instead of tens of grams for scintillation counting.

.5–3.0 million, and requires more than 18 months to complete.By the late 1970s a number of researchers discovered that when accelerating sample atoms in the form of ions to much higher energies in particle accelerators, a much smaller sample was required to derive confident dates—in most cases only milligrams instead of tens of grams for scintillation counting.

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