Blog / Degassing

How to get maximum lifetime from your degasser

Modern online degassers used in liquid chromatography, (U)HPLC, and other instruments handling liquids with high precision and accuracy, are fortunately essentially maintenance-free. However, there are a few things to keep in mind not to shorten the lifetime of your online degasser.

Firstly, one should always use a degassing chamber that is compatible with the solvents that will be used. Organic solvents such as hexane, heptane, toluene, tetrahydrofurane (THF), and dichloromethane (DCM), typically demand specially designed degassing chambers. These degassing chambers are often labelled GPC to highlight their suitability in gel permeation chromatography, but they are equally suitable for normal phase and flash chromatography applications where such organic solvents are also employed.

As with any fluidic component it is advised not to leave your degassing chamber with liquid inside when disconnected from use. This is especially important when there are salts or buffer components dissolved into the liquid since they may precipitate. Precipitates will block the flow path and are notoriously very problematic to wash out again. In addition, buffered aqueous solutions exposed to open air may constitute an attractive environment for microbial growth, which can also cause blockage of the flow path.

Finally, it is strongly recommended to always suck solutions through the degassing chambers, rather than pumping or pushing liquids through them. The internal semi-permeable membrane material that allows gases to penetrate while blocking liquids, is designed to withstand a certain pressure difference. That limit may accidentally be exceeded if liquids are pumped too fast into the degassing chamber, which may cause irreparable damage.

Biotech Fluidics is dedicated to supporting our customers and we look forward to guiding you to the most suitable degasser model for your application. Special design options might also be available on request, including for example, high pressure rated degassing chambers.

Popular one-piece fingertight fittings

The original One-Piece Fingertight Fitting was introduced almost 30 years ago and is still one of the most popular fittings offered by Biotech Fluidics for making liquid chromatography fluid path connections of 1/16 inch OD tubing to standard 10-32 coned ports in HPLC instruments. This PEEK fitting (F-120) can hold up to 345 bar (5000 psi) and is convenient and very easy to use since the only tool it requires are your fingers to tighten the fitting into the receiving port. It is available in colours of natural, blue, black, green, red, and yellow. This fitting also comes in a longer version (F-130) which can be more suitable for instrument designs with alternative layouts but requiring similar performance.

In addition, Biotech Fluidics offers a similarly designed Ultra High-Performance version of the One-Piece Fingertight Fitting. This is called VHP PK One-Piece fitting (PK-120BLK) and can withstand temperatures up to 200 °C and pressures up to 827 bar (12 000 psi) thanks to a proprietary PEEK polymer blend. Note that this material may be conductive to electricity and should thus be used with caution in high voltage applications.

Many of the fittings are available in packs of 10 pieces, as indicated by “x” at the end of the product number. Browse our online catalogue from IDEX Health & Science LLC for more information about fittings or contact Biotech Fluidics for guidance and to discuss your application needs.

High-precision dispensing facilitated by effective degassing
Dissolved gasses present a challenge in most liquid handling situations since off-gassing and the resulting formation of bubbles typically leads to inaccurate results. This is especially troublesome in high-precision dispensing equipment, where exact volumes of chilled solutions must be distributed at high speed during long sequences. The presence of temperature gradients and pressure differences in these setups accelerates bubble formation, which immediately impacts volume accuracy to an unacceptable level. Dispensers are therefore often furnished with alarms that stop and divert the flow if bubbles are detected, which instantly has a negative impact on throughput and productivity.
The most efficient way to reduce formation of bubbles is to resolve the root cause of the problem by removing the excess of dissolved gasses. This is efficiently accomplished by an in-line degasser where a controlled vacuum withdraws dissolved gasses through a gas-permeable membrane that do not allow liquids to pass. The wide range of Biotech DEGASi® PLUS degassers offers flexibility since they are designed to meet several different requirements in terms of volumes, flow rates and solvent compatibility.
The number of daily bubble alarms during dispensing in a production machine carrying nine positive-displacement precision syringes was significantly reduced when the apparatus was equipped with two Biotech DEGASi® PLUS SEMI-PREP 6-channel degassing units. The average number of daily dispensing alarms decreased by nearly 80% when using a degasser and reached a level where this did not significantly disturb the productivity, as displayed in the figure below.

Dissolved gasses in liquid chromatography eluents may increase background levels and can cause bubble formation that severely disturb the baseline and analyses. When performing ion chromatography separations with suppressed conductivity detection for analysis of anions, the penalties of dissolved gasses are typically poorer signal to noise ratio and consequently worse detection levels. The dissolved gasses can also lead to failed analysis if bubble formation coincide with analyte elution and thus disturb peak integration. A convenient way to eliminate all such problems is to install an online degasser between the eluent reservoir and the pump.
The laboratory at Diduco AB in Umeå (diduco.com) has a number of analytical ion chromatography instruments from several manufacturers installed, and they have fitted Biotech DEGASi™ PLUS Classic degassers with 480 µL internal volume to most of these systems to improve results.
“We have noted significantly more stable output from our ion chromatography analysis after installing degassers”, says Tobias Jonsson, CEO at Diduco AB. “The most distinct effect was in our quality control where we consistently use rather weak hydroxide eluents at high flow rates to test every suppressor we manufacture”.
Data from Diduco’s ion chromatography setup for suppressor quality control shows that the background level decreased about 30% and noise reduced by more than 40% when a degassed was installed. The degasser also completely eliminated the random bubble formation that otherwise would have disturbed these test procedures.

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We are very proud to represent IDEX and and their top of the line components for fluidics systems – all to provide our customers with degassers, tubing, fittings, adapters, sensors, filters, valves, HPLC column hardware and more, for a wide variety of fluidic systems, including HPLC and UHPLC instruments.