A New Sample Introduction System of Mass Spectrometer for a Very Small Amount of Gas Mixtures

概要

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A sample reservoir with the capacity of about 30ml contains a very small amount of sample at about 10μHg. At first the upper end of th reservoir is communicated with the ionization chamber through a leak. After a given short time interval the lower end of the reservoir is communicated with reservoir containing a liquid, preferably mercury, and the liquid begins to flow into the reservoir at a rate which is a definite function of time. If now the scanning is performed with a definite time schedule, it may easily be proved that the height of the peak corresponding to a given substance is proportional to its initial partial pressure, which is a necessary condition for the exact analysis of the gas mixtures. The smaller the sample reservoir, the more pronounced is the change with time in relative concentrations of the substances with different molecular weights. But a proper choice of the time function for the flow-in rate of the liquid and the scanning beginningwith ions of lighter component, can largely compensate this tendency. A preliminary test of the present method of analysis for a very small amount of sample was performed with a Ne+N2 mixture contained in the 3 litre reservoir attached to a CEC 21-401 mass spectrometer. The usual macro-analysis and the micro-analysis of the sample were repeated several times alternately. The results obtained with the two kinds of analysis agreed within ±0.5%.
日本質量分析学会の論文