Abstract: Efficiency of fluid analysis can be improved by utilizing a rotary valve capable of sequentially coupling 3 or more buffer chambers to 3 or more tasks. Such a rotary valve can be provided using a rotor having connections that geometrically form parallel chords of a circle. During analysis, such a valve can provide for parallel processing of several tasks and buffers. For example, one buffer chamber can be connected to a cleaning/evacuation port, another buffer chamber can be connected to a sample input port, and a third buffer chamber can be connected to an analytical instrument. Stepping the valve through its various positions can simultaneously move each of the buffer chambers to the next step in an analysis process.

Abstract: The present invention relates to the separation, quantitative measurement, and analysis of trace species using a combination of three steps in succession. First, trace species are separated from other species that are present. Second, the trace species are chemically modified to convert them into specific species that are advantageous for the third and final step. In this last step, cavity enhanced optical detection of the converted species is performed to detect and measure the concentrations of the species of interest. Because the last step has spectroscopic resolution, the concentration of isotopologues in each converted species can be determined. Further processing can provide the ratios between pairs of isotopologues, in particular the ratio of the rare isotopologues to the most abundant isotopologue.