HPLC pumps from the basic part accessory of HPLC instrumentation. Without proper pump HPLC analysis can be tough and also impossible. HPLC pumps used should suffice some requirements like sufficient pressure generation, suitability to wide range of solvents used, uniform pressure or flow rate, easy to use and also preferably inexpensive.
HPLC pumps are of three types like
- screw driven syringe pump
- reciprocating pumps and
- pneumatic pumps .
Syringe type hplc pump:
This work by producing a pulse-less delivery and by this the flow rate of mobile phase is very well controlled. They are suitable for isocratic hplc run where only a single mobile phase is used.
They have their limitations like small injection volume and one cannot use them to run gradient mobile phases i.e. multiple mobile phases in a single run.
This is most widely used pumps. Here the mobile phase is pushed by back and froth action of piston action present about a cylindrical chamber.
It is widely use due to the following reasons.
- Good pressure generation.
- Constant flow rate.
- Useful for both gradient and isocratic runs.
- Space occupancy is low.
Pneumatic pump is another simplest pumps. As the name indicates (pneumatic) there is use of gas to pressurize the mobile phase present in a collapsible solvent container. They have some advantages like low-cost or inexpensive to purchase, pulse free and also simple.
But are not widely used due to disadvantages like low pressure generation, low capacity to dispel the mobile phase and also the pumping rate varies with viscosity of the mobile phase used.
Reciprocating pumps are used most and they are used as a single pump or dual or multiple pumps to meet the needs of the analysis like isocratic or gradient elution etc. They in most advanced instruments are controlled by software with regards to their pressure and also flow rate.