| 摘要 |
1,263,737. Gas chromatography. BRYGGERIINDUSTRIENS FORSKNINGSLABORATORIUM and SENTRAL-INSTITUTT FOR INDUSTRIELL FORSKNING. 11 Feb., 1969 [14 Feb., 1968], No. 7340/69. Heading B1X. [Also in Divisions F2 and G3] Enhanced discrimination and sensitivity in the gas chromatographic analysis of samples held in tube 11 is achieved by heating tube 11, through which carrier gas is passing, so rapidly that transfer to column 13 is achieved by thermoinjection, the carrier gas being passed through flow resistrictor 18 upstream of the precolumn so as to establish sufficient pressure differential to prevent back pressure. Initially, a sample is passed through selection unit 110 in a stream of carrier gas, valve 19 (see Division F2) being kept open by a flow of carrier gas from source 17, so that the sample condenses and is trapped in tube 11 which is immersed in a bath 12 of solid carbon dioxide or liquid nitrogen. When the trapped sample is to be investigated, valve 19 is closed by carrier gas from source 20 and valve 15 is closed to the atmosphere by carrier gas from source 16. Tube 11 and contents are then heated for less than 1 second to 150-200‹C., causing the sample to volatilise and be carried to column 13 in the stream of carrier gas. Constructional details are also provided of gas flow restrictors 18, 112 (see Division G3), of thermoinjector tube 11 and of selection unit 110, which latter enables the system to be operated in a number of different modes for different purposes. |
