Homemade Marker for Chromatography Plates performance on thin layer chromatography plates is best if one cuts channels through the dry plate coating pmdlel to the direction of the developer flow. Parallel uniform channels are required, however, so that the flow rate of the developer will be the same in all areas of the plate. A pocket-comb scribing jig will cut reproducible channels without marring the plate surface. Approximately oneem pieces are cut from the even-numbered teeth of a pocket comb, and '/%-crnpieces from the teeth that remain (a nail clipper will do the job nicely). The longer teeth can then be evened by stroking the comb over sandpaper. When the inside of the frame of the comb is butted against the side of the plate and the jig is d r a m over the coating, the longer teeth will cut through the powder and make remarkably uniform channels. Wider paths for larger samples can be made by removing more teeth from the comb.
Volume 43, Number
I , January 1966
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29
