GB872905A - Improvements in or relating to frames for use in two dimensional paper chromatography - Google Patents

Abstract

The chromatography frame comprises end plates 1 and 2 arranged in parallel by means of fixed spacers 3. Two pairs of paper supporting <PICT:0872905/III/1> <PICT:0872905/III/2> <PICT:0872905/III/3> bars 4 and 5 respectively extend perpendicularly to the end plates between opposite top and bottom corners of the plates with a floating connection with the end plates. The ends of the supporting bars 4 and 5 are pivotally connected with carrier arms 6 running in diagonal directions along the insides of the end plates 1 and 2. These arms 6 have bosses 7 extending through slots 8 in the end plates and fitted with bushes 9 outside the end plates and on which bear light stainless steel springs 10 to load the bars 4 and 5 for outward movement. Each supporting bar has a series of spaced transverse slots adapted to locate the paper sheets (only one, 11, of which is shown) in spaced relationship parallel to the end plates. The slots 12 on the bars 5 which are at the bottom of the frame when it is in use are preferably arranged to receive the bottom edges of the paper sheets 11 near the corners of the sheets and the slots 13 in the other two bars 4 are preferably arranged to receive the side edges of the sheets near the top corners. Each supporting bar has a longitudinal bore in which a removable skewer 14 is located. The paper sheets 1 are inserted into the frame and engaged in the locating slots 12, 13. The skewers 14 are then inserted in the longitudinal bores in the bars, 4, 5 during which operation they will pierce holes in the sheets. When all the skewers have been completely inserted in the bores the locking device 15 is released so that there is a tendency for the paper sheets, the corners of which are held by the skewers, to be stretched under the action of the loading springs 10 as the cam followers 17 of the carrier arms 6 are free to move outwards. The loading by the springs 10 is such that if one of the sheets 11 is tighter than the other, the holes produced in that sheet by the skewers 14 may tear very slightly. In this way the frame can move to stretch the other sheets evenly and no further tearing will take place as soon as the strain is taken by two or more sheets. The sheets must be loaded with their fibre axes parallel.