Why is a pump required in HPLC?
An HPLC pump is also called a “solvent delivery system.” The purpose of the pump is to maintain a constant flow of mobile phase through the HPLC system. A standard HPLC pump can pump against back pressures up to 6,000 psi where a uHPLC pump typically exceeds 8,500 bar and can go as high as 20,000 psi or more.
Which pumps are used in HPLC?
Most HPLC pumps are reciprocating pumps. The solvent is drawn into a small chamber (with the solvent check valve open) and pumped out of it (when the column check valve is open) by the back and forth motion of a motor driven piston.
What causes pressure drop in HPLC?
A pressure being constantly too low can be a sign of a small leak or air bubbles in the pump system. Do not forget the obvious reasons, such as a too low flow rate or different column temperature. Even a blocked suction filter in the solvent bottle can lead to reduced pressure.
How many types of pumps are there in HPLC?
Types of HPLC pump hplc-pump-types Three common types of pumps are constant pressure pumps, syringe type pumps and reciprocating piston pumps.
What is back pressure in HPLC?
High Back Pressure is defined as an unexpected increase in the pressure readings during normal HPLC operation that approach or exceed the maximum pressure capability of the system. Higher than expected pressure is the most often reported problem in HPLC.
How many columns are used in HPLC?
Types of HPLC columns: There are four types of HPLC columns used in liquid chromatography.
What is the difference between high pressure and low pressure HPLC?
A low pressure gradient system consists of one pump with an integrated mixing block that enables the delivery of up to four different solvents at the same time. High pressure gradient systems are composed of two pumps. These systems are limited to two solvents which are pumped by the separate pumps.
What causes RSD failure in HPLC?
Column temperature fluctuations (especially evident in ion exchange systems). Column overloading. (Retention times usually decrease as mass of solute injected on column exceeds column capacity.) Sample solvent incompatible with mobile phase.
Why are there negative peaks in HPLC?
Negative peaks are most often caused by difference in refractive index between the sample solvent, sample and mobile phase. They are also caused after routine maintenance when the system has not been reconfigured correctly.