Patent GB-1027093-A (GB)
Title: Improvements in chromatography
IPC: G01N30/20
Filed: 1963-07-12
Abstract: 1, 027, 093. Chromatographic separation of fluid mixtures. PERKIN-ELMER CORPORATION. July 12, 1963 [July 18, 1962], No. 27749/63. Headings B1L and B1X. Mixtures of fluids are separated by chromatography wherein the mixture is passed sequentially and repeatedly through a number of chromatography columns, components, if any, which are ahead of a preselected portion of the mixture are removed and a previously used column is backflushed to remove from this column unwanted components behind the preselected portion and the preselected portion is subsequently passed through the said previously used column. This method may be applied to gas-liquid, gas-solid, liquid-liquid and liquid-solid chromatography and is described in relation to the separation of a middle fraction from a mixture by gas chromatography. In embodiments, two, three or multiples of three columns are used wherein the columns are connected by valves which allow recirculation of the mixture and removal of the unwanted components (Figs. 1 and 3 to 5, not shown). In one embodiment , a fluid mixture, is allowed to pass through two columns with a detector interposed therebetween and wherein the lighter fractions are allowed to leave the front of the second column while the heavier fractions are prevented from entering the second column by altering the connections between the columns immediately after the middle fraction has passed into the second column. The heavier fractions in the first column may then be eluted by backflushing with a purge gas. Simultaneous with the altering of the connections between the first two columns, the second column is joined to a third via a detector and a similar proceedure used regarding the lighter and heavier fractions. The first column is used again for the separation but with the flow in the reverse direction when the connections between the columns are changed again and thereupon column two is purged of heavier fractions. By altering the connections between the three columns, six combinations are obtained and the mixture passed through this cycle of combinations repeatedly. Such an arrangement to produce this effect is shown in Fig. 2, three columns 10, 20 and 30 are connected to a multiport valve 40 which has carrier or purge gas sources P 1  and P 2 , vents V 1  and V 2  and detector 12, and wherein the various positions of the valve governs the combination of the columns and direction of flow of both carrier and eluting gases. In Fig. 6, valve 116 has gas sources P 1  and P 2  at different pressures the higher pressure being used to purge one column quickly while the mixture is passing down the other column prior to linking the columns in series again. The valve governs a two column 80 and 90 arrangement which is mounted on a valve rotor 110 which together with valve 116 allows the combination of and flow directions through the two columns to be altered. The purge or eluting gas may be heated and is not necessarily used at the same pressure as the carrier gas. Two samples may be injected simultaneously into two columns when a six column arrangement is used. If the lighter components of the mixture are sought then these are not vented but passed on to the next column whilst pure carrier gas would be vented or recycled.