Abstract: The difference in concentration of a selected isotope in two materials is measured by directing gaseous beams of the materials towards the inlet of a mass spectrometer. A shutter alternately blocks transmission of the two beams. Means is also provided for blocking either of the two beams for any period of time desired. Provision is made for automatically passing either one of the gaseous beams or both of the gaseous beams through the shutter to the mass spectrometer. The output signal from the mass spectrometer is passed to a synchronous detector as is a reference signal which is representative of the speed of operation of the shutter. The output signal from the synchronous detector is representative of the concentration of the selected isotope in a first material if only the gaseous beam of the first material is being passed through the shutter to the mass spectrometer.

Abstract: The difference in the concentration of a selected isotope in a first material and a second material, which may be a reference material, is measured by means of a mass spectrometer. The analysis is carried out with only a small amount of sample by introducing only a small slug of sample of the first material into the mass spectrometer by means of a sample valve. If there is a sufficient quantity of the second material, the first material my be compared directly to the second material. Direct comparison is also used when the second material is a reference material. If there is also only a small supply of the second material then the first material is compared to a reference material and in like manner the sample valve is utilized to supply a small sample of the second material to the mass spectrometer to be compared to the reference material. An indirect comparison of the first and second materials is thus provided.

Abstract: Electromagnetic radiation is detected, using a photoacoustic cell employing a uniform absorber of radiation which absorbs independently of wavelength.

Abstract: An apparatus and method for separating and collecting chromatographic samples in which three separate chromatographic columns are cycled through an elution mode, an elevated temperature back-flush mode, and a cooling back-flush mode in continuous repetition so that at any one time one of the columns is in an elution mode, another of the columns is in elevated temperature back-flush mode, and the remaining column is in cooling back-flush mode.

Abstract: A process for the removal of radon from hydrocarbon streams by insertion and removal of radon-selective carriers.