A Simple Method for Sample Application in Chromatography Paper chromatography and thin-layer chromatography are two of the indispensable analytical methods in most chemical and biochemical laboratories. Proper application of the sample onto the filter paper or the thin-layer plate is probably the mast important single factor for successful chromatography. So that a chromatogram with high resolution can he obtained, only asmall spot Rubber Bul or narrow streak of the sample should be made on the paper or plate. Commercial applicators are useful, hut they are usually expensive and sometimes unavailable. Therefore, I have devised s simple and convenient method for making an applicator. Capillary A fine capillary, 5-8 cm long, is cut from a piece of glass tubing and is then inserted directly into a rubber bulb (see figure). To fill the applicator, one simply places the end of the capillary into the sample solution, holds the h u b between the thumb and the middle finger, and then places the forefinger on the mouth of the hulh. By stopping the mouth of the hulh and squeezing the bulb with the fingers, a very small amount of the sample can then be applied to the paper or plate. This method is especially advantageous in the case of thin-layer chromatography because the sample can he deposited without disturbing the surface of the plate. However, it is useful for both paper and thin-layer chromatography in that it allows rapid application of a small amount of the sample. J. M. LO National Tsing Hua University Hsinchu, Taiwan. 300 Republic of China
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Chemical Education
