Column chromatography in chemistry is a method used to purify individual chemical compounds from mixtures of compounds. It is often used for preparative applications on scales from micrograms up to kilograms. The main advantage of column chromatography is the relatively low cost and disposability of the stationary phase used in the process. The latter prevents cross-contamination and stationary phase degradation due to recycling.
The classical preparative chromatography column, is a glass tube with a diameter from 5 mm to 50 mm and a height of 5 cm to 1 m with a tap and some kind of a filter at the bottom. Two methods are generally used to prepare a column: the dry method, and the wet method.
⁕For the dry method, the column is first filled with dry stationary phase powder, followed by the addition of mobile phase, which is flushed through the column until it is completely wet, and from this point is never allowed to run dry.
⁕For the wet method, a slurry is prepared of the eluent with the stationary phase powder and then carefully poured into the column. Care must be taken to avoid air bubbles. A solution of the organic material is pipetted on top of the stationary phase. This layer is usually topped with a small layer of sand or with cotton or glass wool to protect the shape of the organic layer from the velocity of newly added eluent. Eluent is slowly passed through the column to advance the organic material. Often a spherical eluent reservoir or an eluent-filled and stoppered separating funnel is put on top of the column.
Columns
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A neverending puzzle game made originally for segas 16bit arcade hardware and ported to the Megadrive.
Was later ported to the 8bit Master System but the less said about that the better.
Often wrongly referred to as a tetris clone as the gameplay is completley different - colored gems must be aligned together to destroy them and prevent them filling the screen. Columns pwns Tetris ass all night long
This was where the fun began, Without the arcades timing system constantly badgering you for money you are free to start a game of colums and forfeit the rest of the day. The haunting music in your dreams for eternity.
Eventually as the game speeds up the gems can be slowed by dropping them, but by this stage you aint blinked in an hour and the game seems to be playing itself any way.
More adictive than crack; A truly great game.
Is basically a metaphor for life, but I aint got time to explain
A universal excuse for not doing something.
Columns meaning & definition 1 of Columns.