Prototype cavity ring-down spectroscopy instrument for 14C measurements

A commercial cavity ring-down spectroscopy (CRDS) instrument for the measurement of ¹⁴C in biological studies has been developed through a Cooperative Research and Development Agreement between Picarro, Inc. and Lawrence Livermore National Laboratory—where much of the initial research and development was performed. CRDS is a highly sensitive optical spectroscopic technique that enables the measurement of absolute optical extinction by samples that scatter and absorb light. It has been widely used to study gaseous samples that absorb light at specific wavelengths and in turn to determine the concentrations of species in the gas at mole fractions down to the parts per quadrillion level. 

The major components of the prototype commercial instrument include a quantum cascade laser, a high-finesse optical cavity, a mid-infrared detector, and a refrigeration system. Initial measurements performed by a third-party vendor have shown that the system has sufficient accuracy and precision for the quantification of ¹⁴C-tracer-labled tracer pulse-chase studies for biomedical applications. Throughput is approximately 100 samples a day and the cost of the instrument will be substantially less than that of a conventional Accelerator Mass Spectrometry (AMS) ¹⁴C system.

In the past, low-level ¹⁴C tracer studies for biology were processed by AMS facilities. Although AMS systems can detect extremely low concentrations of ¹⁴C, they are expensive, large, and complex, and the required sample preparation is time-consuming. Quantification of ¹⁴C by CRDS offers an approach that eliminates many of the shortcomings of accelerator-based systems. The availability of simple, inexpensive CRDS instruments could enable the proliferation of ¹⁴C tracer techniques to aid the biomedical and environmental science communities. A tabletop-sized CRDS system can now conduct most biomedical studies previously performed with AMS. 

The initial development of this technology was supported by a Laboratory Directed Research and Development project (11-ERD-044).