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CRD Carbonate Removal Device

Reduces Carbonate for Improved Sensitivity

The Thermo Scientific Dionex Carbonate Removal Device (CRD 180, 200 and 300) remove carbon dioxide from the suppressed eluent stream by diffusion through the walls of a carbonate selective gas permeable membrane. With carbonate eluent systems the Dionex CRD 300 reduces the background signal to nearly the same levels as that of hydroxide eluents. Plumbed after the suppressor, the carbon dioxide transfer is aided by a countercurrent flow of basic solution.

  • The Dionex CRD 180 and 200 are optimized for the removal of carbonate from hydroxide eluent systems
  • Minimizing carbonate using the Dionex CRD 180 or 200 can improve quantification
  • The reduced membrane length of the Dionex CRD 180 is optimized for columns based on 4 µm resins
  • The increased membrane length of the Dionex CRD 300 is optimized for carbonate eluent systems
  • Reducing the baseline with a Dionex CRD 300 results in higher sensitivity for carbonate eluent systems
  • Elimination of the carbonic acid background with a Dionex CRD 300 increases the linearity range

Dionex CRD 200 Carbonate Removal Device

Exposure to carbon dioxide can cause samples to become contaminated with carbonate. High levels of carbonate originating from dissolved carbon dioxide can interfere with the accurate determination of analytes of interest, such as sulfate and nitrite. The Dionex CRD 200 is a device used to remove the carbonate peak contributed by the sample.

The Dionex CRD 200 can be installed easily in any Thermo Scientific Dionex IC system equipped with an eluent generator, Thermo Scientific Dionex CR-ATC Continuously Regenerated Anion Trap Column, and Thermo Scientific Dionex AERS 500 Anion Electrolytically Regenerated Suppressor or Thermo Scientific Dionex ACES 300 Anion Capillary Electrolytic Suppressor, and requires no reagents or software control. The Dionex CRD 200 is a low-dispersion devices designed specifically for use with hydroxide- and borate-based chemistries using Thermo Scientific Dionex columns.

The Dionex CRD 200 is available in three formats. The Dionex CRD 200 (4 mm) supports carbonate removal from standard bore systems, while the Dionex CRD 200 (2 mm) supports carbonate removal from microbore systems; the Dionex CRD 200 (0.4 mm) supports carbonate removal from capillary-scale systems at flow rates of 5 – 30 μL/min.

A significant amount of carbonate is removed using the Dionex CRD 200 Carbonate Removal Device.

Dionex CRD 300 Carbonate Removal Device

Carbonate eluents are suppressed to relatively low-conductivity carbonate acid, but the residual conductivity of the carbonic acid has several undesirable effects. Carbonic acid can mask small peaks, decreasing the limit of detection (LOD) during trace analyses. In a background of carbonic acid, the linear range of most species is limited, and the residual background conductivity creates a large void dip which can hamper the integration of early eluting species. The CRD 300 is a device used to remove the carbonic acid from the suppressed eluent, providing hydroxide-like detection to systems using carbonate eluents.

The Dionex CRD 300 can be installed easily in any Dionex IC system running carbonate as an eluent with a Dionex AERS 500 suppressor. The Dionex CRD 300 requires either a constant flow of basic solution from a peristaltic pump or evacuation by a vacuum pump. The Dionex CRD 300 is designed specifically for use with carbonate eluent based chemistries using Dionex columns.

The Dionex CRD 300 is available in two formats. The Dionex CRD 300 (4 mm) supports carbonate removal from standard bore systems, while the Dionex CRD 300 (2 mm) supports carbonate removal from microbore systems.

Background signal is reduced using the Dionex CRD 300 Carbonate Removal Device.

Dionex CRD 180 Carbonate Removal Device

The Dionex CRD 180 is a version of the Dionex CRD 200 that has reduced internal volume. This facilitates operation in conjunction with 4 μm resin packed capillary columns without unacceptable loss of peak efficiency. However the Dionex CRD 180 has less capacity for the removal of carbonate than the Dionex CRD 200, and is therefore not recommended for use with columns packed with resin larger than 4 μm.

The Dionex CRD 180 can be installed easily in a Dionex Capillary IC system equipped with an eluent generator, Dionex CR-ATC Continuously Regenerated Anion Trap Column, and Dionex ACES 300 suppressor. The Dionex CRD 180 requires no reagents or software control. The Dionex CRD 180 is an ultra-low-dispersion device designed specifically for use with hydroxide-based chemistries using Dionex columns.

The Dionex CRD 180 is only available in capillary (0.4 mm) format for use with 0.25 mm and 0.4 mm capillary columns. Microbore and standard-bore systems using 4 μm resin packed columns should use the Dionex CRD 200.