A Slmpllfled Method for Loading a Narrow Separation Column Frequently, we are forced t o work with a very small amount of compound during liquid chromatography, and, since there is little product to work with, we must use a narrow separation column t o gain an effective result. Up to now, loading a narrow column has proven very difficult. Silica suspensions do not readily "float" to the bottom of the column, and air gets trapped inside-allowing the solventtoevaporate--eausing a "crystallization" effect on the silica. We have found a simple method that allows trouble-free loading in a relatively short time. The first step is t o set up the column (see figure). Securely connect the regulator valve, and leave i t closed. Insert a small amount of glass wool through the top of the column using a narrow instrument or wire, and push the wool down t o the hottom. By inserting the wool after attaching the regulator valve, we can he sure no fibers will he tangled in the threads, allowing for slow leakage once solvent is added. When this is done, place the column on a stnnd. --.-held hv ..-~--, .* clnmna. Next we fill our column with the solvent, and only solvent, approximately five-sixths full (mark that level on the column). Having already prepared a silica suspension (silica and solvent), we are ready to continue. Using a 9-in. disposable Pasteur pipet, we transfer a small amount of the suspension to the column. Be sure to have the pipet tip below the solvent level. By loading this way, no air will contact the silica. Slowly eject the suspension, stopping when the content level reaches top of the column. Open reeulstor valve sliehtlv. .. . allowine some solvent to drin out. This will also helo the silica settle faster. When solvent level has reached the starting point, close the valve, and again transfer suspension to column. Hgcuntinually piperring thesuspension in t h ~ manner, s you will find that inapproximately five minuter sour column will have been loaded trouble-free, without mwnnted air trapped inside the silica. Marc Tantlllo Management Information System Department Long Island Jewish Medical Center New Hyde Park. NY 11042
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254
Journal of Chemical Education
