Packed column:

The category of column most generally used is the packed column whereas the tubing is filled along with a coated solid support, polymer or absorbent. Glasswool that is commonly used to retain the packing along the column is placed on both sides of column. The end of the column that is fitted to the sample introduction system commonly has 4 to 6 cm of glasswool, while the opposite or the detector end has about 6 mm of glasswool. The schematic of a packed column is display in Figure.

Figure:  Packed column

In common, stainless steel columns are used, packed where straight to acquire a uniform packing and coiled to facilitate long lengths. The spiral diameter should be at least ten times the column diameter to minimize diffusion and racetrack effects if coiled. Packed column lengths vary from a few centimeters to various metres. General analytical columns are 1 to 3m in length. Column diameters vary from 0.25 mm to 50 mm I.D. and larger. As smaller the column diameter as the higher the column efficiency. Standard analytical columns are of 3 mm to 6 mm I.D.