US Patent 6890489 Mass rate attenuator

While a large primary stream (24) of analytes flow from a chromatographic column (20) to containers of a receiver (108), small samples of the analytes are diverted for flow to a mass spectrometer (54) for analysis, by use of a transfer module (102). The transfer module includes a stator (110) and a rotor or shuttle (114). The shuttle has an aliquot passage (120) that initially lies in a first position where the primary stream flows through it so the aliquot passage receives a small sample. The shuttle then moves to a second position where the aliquot passage (at 122) is aligned with a pump (134) that pumps fluid out of the aliquot passage to the mass spectrometer.