Extra Column Dispersion - Low Dispersion Gradient Elution Apparatus > Page 50
Low Dispersion Gradient Elution Apparatus
Gradient elution with high efficiency low dispersion columns, particularly small bore columns that operate at very low flow rates, present another instrumental problem for the designer of the modern chromatograph. Not only must the gradients be formed accurately and precisely, they must be also formed at very low flow rates and sometimes the total volume employed for the analysis will be less than 1 ml. The apparatus can be basic and accommodate only to solvents systems. It usually consists of two pumps controlled by an appropriate solvent programmer special modified to cope with the small flow rates used with small volume columns.
Figure 25 A Low Volume Mixing T