BPE-001 Ion chromatography eluent preparation unit

Aquilon has created a very convenient unit for the Stayer-M system, structurally and from the point of view of control, combining a generator and a suppressor of background conductivity of the eluent. Thus, the user receives a single unit that completely takes care of all the problems of obtaining an eluent of the desired composition.

Ion chromatography eluent generator

For the separation of anions by ion chromatography, alkaline eluents are often used, which, in some cases, give better results than carbonate-bicarbonate buffer solutions. For all its advantages, alkali solutions are difficult to use, since they are rather difficult to prepare in an accurate concentration and must be protected from the access of carbon dioxide from the air.

An electrochemical eluent generator allows you to obtain an alkaline eluent from concentrated solutions of potassium or sodium carbonates and deionized water using the principle of electrodialysis. The resulting accuracy and reproducibility of the eluent composition is fundamentally unattainable in the case of manual preparation of solutions.

The chromatograph pump supplies clean water to the generator inlet, and the generator outlet produces an alkali solution with a concentration that is precisely determined by the eluent flow rate and the generator current, according to Faraday's laws. Software control of the current passing through the generator allows you to use not only isocratic, but also gradient separation.

A significant difference between this generator and its available analogues is that both electrodes are placed outside the eluent generation chamber. This eliminates gas formation in the high-pressure path of the liquid chromatograph, which dramatically reduces noise and baseline drift. When designing the generator, the developers abandoned the cartridge principle, which allows users to choose the sodium or potassium eluent independently and does not limit the operating time by the cartridge capacity.

Typically, ion chromatographs use pumps made of PEEK both to avoid contamination of the eluent and to avoid corrosion. In combination with the eluent generator, you can use any pump, including a metal one, since it supplies only clean water.

Main features of the generator

• The generator design eliminates gas formation in the liquid path of the chromatograph, which minimizes noise and baseline drift.
• A built-in peristaltic pump provides a user-selected supply of working solution from an external container.
• The principle of operation of the device provides unique stability and reproducibility of the eluent composition in both isocratic and gradient modes.
• he stepwise eluent concentration gradient allows you to use the analyte accumulation mode in the separation column itself.
• Switching on the specialized regenerating cartridges at the detector outlet puts the chromatograph in closed-loop mode. Only a small regular addition of water is required to compensate for losses.
• The generator can operate both under the control of chromatographic software and as a stand-alone module as part of any ion chromatograph.

Electrodialysis background conductivity suppressor

To separate anions by ion chromatography, it is necessary to suppress the background electrical conductivity of the eluent by replacing alkali metal ions with protons. The use of suppressive columns with a cation-exchange resin for these purposes not only requires a periodic procedure for their regeneration, but also drastically degrades the efficiency of the method due to a strong blurring of peaks. Capillary suppressors are devoid of this drawback, but they require periodic replacement of the regenerating solution, do not cope well with the suppression of the conductivity of concentrated eluents and are of little use for gradient chromatography.

To solve the problem of suppressing the background conductivity of the eluent, Aquilon offers to use an electrodialysis suppressor of the background conductivity. The device provides the necessary sensitivity for the analysis of anions using carbonate-bicarbonate, borate and alkaline eluents. The design of the instrument minimizes the blurring of chromatographic peaks. The electrodialysis suppressor provides a good signal-to-noise ratio over a wide range of concentrations and eluent flow rates, which allows it to be used in conjunction with an eluent generator in gradient methods of anion analysis.

An additional advantage is the presence of a replaceable cartridge, which makes it possible to quickly replace the cartridge with the end of its resource by the users themselves.

Main features of the suppressor

• The non-removable cartridge, made of an inert and stable PEEK material, allows the use of aggressive media if necessary.
• The peristaltic pump of the device makes it possible to operate not only in the electrochemical mode, but also, using an external regenerating solution, in the mode of chemical suppression of background electrical conductivity. This mode can be useful in cases where highly concentrated eluents are used.
• An integrated peristaltic pump allows deionized water to be pumped into the external chambers of the suppressor, further reducing noise and increasing sensitivity.
• The possibility of using the eluate after the detector to flush the external chambers ensures convenient operation and a minimum number of external hydraulic connections.