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Geochron Laboratories services

Tritium Analyses

Tritium (3H) is a short-lived radioactive isotope of hydrogen which decays by beta emission to stable 3He. The half-life of tritium is 12.43 years. Tritium analyses are reported in units of concentration called Tritium Units (TU), where one TU is one tritium atom in 1018 atoms of hydrogen. Tritium analyses can also be reported in units of radioactivity (picocuries) per unit volume. One picocurie is 2.22 disintegrations per minute (dpm). A liter of water with a tritium concentration of 1 TU would yield about 7.1 dpm, which is equivalent to 3.2 picocuries per liter (pC/l). At Geochron, the tritium activity in water samples is determined by liquid scintillation. By using a long (2000 minute) counting period, we obtain a detection limit of about 4 TU or 14 pC/l. Geochron"s tritium detection limit may not be appropriate for some groundwater studies. Feel free to contact us to discuss the applicability of our service to your particular problem.

Radiocarbon Age Determinations

Radiocarbon dating is the principal method for determining the age of carbon-bearing materials from the present to about 50,000 years ago. The method takes advantage of the natural occurrence of a radioactive isotope of carbon (14C or "Carbon 14"). 14C is continuously produced in the upper atmosphere by the interaction of cosmic ray neutrons with 14N. The newly formed 14C rapidly oxidizes to carbon dioxide which is taken up by plants during photosynthesis, and also mixes with carbon dioxide dissolved in the hydrosphere.

Stable Isotope Ratio Analysis

Stable isotope ratio analysis is the precise measurement of the abundance ratio of two stable isotopes of a particular element. Many elements have two or more naturally occurring stable isotopes. Since the isotopes of a particular element have identical chemical properties but slightly different masses, they may enter into chemical reactions at different rates which can induce local variations in isotopic composition. The measurement of these variations can reveal information about the origin and/or the processes that have affected the material analyzed.