Syringe Filter Efficiency on HPLC Column Life

Injection of particulate-laden samples will plug High Performance Liquid Chromatography (HPLC) columns, shorten injector life, and result in extensive maintenance on pumps. Particulate finding its way into a column results in increased column backpressure, disrupted nominal band shape, and reduced plate number, consequently shortening column life and making analytical results difficult to interpret. Using Membrane Solutions syringe filters with GHP (hydrophilic polypropylene) membrane is the most efficient way to remove particulate and prolong the life of HPLC system components. Membrane Solutions’ syringe filters with GHP membrane are widely used for this purpose. The average retention efficiency of 0.45 µm rated syringe filters with GHP membrane at removing 0.45 µm average diameter latex spheres is 94.9%. Compared to filters from two other manufacturers, Membrane Solutions syringe filters significantly prolonged HPLC column life with virtually no backpressure increase after 972 injections.

Of the four common causes for HPLC column failure (plugging, voids, adsorbed sample, and chemical attack), plugging is the most frequently encountered by analytical chemists or analysts. Injection of samples containing particulate will eventually block the column inlet, cause high column backpressure, and shorten the normal lifetime of the column. Operations of pump components, injectors, and detectors can be expected to be less troublesome when fluids are filtered. For HPLC applications, the 0.45 µm pore size filter is typically selected for removal of particulates. Although there are several seemingly equivalent such products on the market, lack of knowledge about the differences between filters leads to ore frequent column replacement and extensive operation downtime.

Filtration as a preventative maintenance tool for HPLC analyses is well documented. It is commonly taken for granted that column life will be extended if samples are filtered prior to injection, but the extension of the column life has not been well quantified. It is the intent of this work to demonstrate that filter efficiency must be considered when choosing an HPLC sample-prep filter and that filtration will lengthen the life of a column.

In this paper, retention efficiency of three effectively equivalent 0.45 µm rated syringe filters was examined using 0.45 µm average diameter latex spheres. This work was conducted with latex spheres to offer the best possible reproducibility in both sample preparation and filter efficiency measurements.

In order to correlate the retention of spheres to the actual application, the quantitative effect of filtration on HPLC column life was investigated. This involved examining column life without filtration compared to column life when samples were filtered. It should be recognized that extending the column life is dependent on the particulate within the sample and actual column life extension may vary.

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