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High performance liquid chromatography requires extremely accurate pumping systems delivering an accurate, precise and pulse-free flow of the mobile phase.

An HPLC pump system is a complex device with multiple moving parts subject to wear. Standard operating procedures should be in place to both minimize wear such as caused by particulate matter settling in valves and other components, and having spares on hand to replace components subject to wear (i.e. valves, piston and piston seal components). As one of many maintenance steps it is always a good idea to flush your HPLC system with rinse solvents after analysis with buffered mobile phases.

HPLC Pumping System Problems are not Uncommon

A review of the literature discloses that pumping system malfunction ranks high as the cause of incorrect readings. We will not go into detail here other than to make that point. While preventative maintenance is certainly important – such as periodically replacing piston seals – one sure way to minimize if not completely head off incorrect HPLC measurement is periodically checking the pump flow rate. This is accomplished by scheduling routine performance verification of the HPLC system, which includes testing for pump flow rate accuracy.

As a slight aside, a point we at Tovatech like to make is not to equate accuracy with precision.   Remember that an HPLC system may test out as precise – always giving the same result – but it may be precisely inaccurate.  In contrast, legendary William Tell and Robin Hood are rumored to be precisely accurate in bowmanship.

When and How to Recalibrate HPLC Systems

In this case “when” is usually guided by regulatory bodies.   In “how” there is a choice:  the hard way and the easy way.   As noted in our HPLC flowmeter buyer’s guide, chemists can measure flow rates by using a timer and either volumetric or gravimetric measurement of collected solvent.  This is time consuming, tedious and prone to operator error.  A far superior method for pump flow rate measurement is accomplished with a liquid flow meter such as the FlowCal 5000 flowmeter compatible with all HPLC systems.

Simplicity of use is a strong point for frequently testing HPLC systems with this 12-ounce portable digital flowmeter. The unit is supplied with a traceable calibration certificate.  It measures flow rates from 0.05 to 25 ml/min with an accuracy of 1% of the digital readout making it a great tool for IQ, OQ and PQ validations. Performance data can be transferred to a computer or printer for record keeping.The FlowCal 5000 can also be used to diagnose common HPLC pump system problems.

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