IonPac NS1 Manual
Document No. 034024-06
Page 12 of 35
3.6
Regenerant Preparation for the AMMS-ICE II
5 mM tetrabutylammonium hydroxide (TBAOH) is the recommended regenerant for use with the Anion-ICE II MicroMembrane
Suppressor (AMMS-ICE II). Tetramethylammonium hydroxide or potassium hydroxide may be used as alternate regenerants, but
cause higher background conductivity and therefore compromise total system performance. For ease of preparation and guaranteed
purity, use Dionex Cation Regenerant Solution (P/N 039602). For detailed information on the operation of the AMMS-ICE II, see
Document No. 032661.
3.7
Using AutoRegen and Eluents Containing Solvents
When performing Mobile Phase Ion Chromatography (MPIC) using an Anion MicroMembrane Suppressor for Mobile Phase Ion
Chromatography in the analysis of anions with ion pair reagents (AR1 or AR2) or a Cation MicroMembrane Suppressor in the
analysis of cations with ion pair reagents (CR1 or CR2) and a Conductivity Detector Module, Dionex recommends using an
AutoRegen Accessory (P/N 039594). Typical regenerant flow rates required in MPIC analyses varies from 5 to 15 mL/min.
The use of an AutoRegen Accessory saves regenerant preparation time and reduces regenerant consumption and waste. However,
when using an AutoRegen Accessory to continuously remove contaminants from the regenerant and restore the regenerant to the
correct state, it is necessary to replace the regenerant on a regular basis. How often the regenerant is replaced will depend on the
application and the concentration of the solvent in the eluent. Minimally, the regenerant should be replaced once a week. It is not
necessary to change the AutoRegen Regenerant Cartridge until it is completely expended.
Solvent, much like the sodium ions, passes through the membrane of the MicroMembrane Suppressor from the eluent to the
regenerant stream. The solvent and the sodium ions are carried from the suppressor to the regenerant reservoir by means of the
regenerant stream. As the recycled regenerant is pumped through the AutoRegen Regenerant Cartridge, the sodium ions are
exchanged for hydrogen ions. However, the solvent is not removed from the recycled regenerant and continues to accumulate in
the recycled regenerant stream. Eventually the concentration of solvent in the recycled regenerant can cause the background
conductivity to increase which can result in a noisy background. Most solvents have no affect on the cartridge lifetime.
In all cases, the ionic strength of the eluent determines the lifetime of the AutoRegen Regenerant Cartridge. However, if the eluent
contains acetonitrile and is used with a cation AutoRegen Regenerant Cartridge in the AutoRegen Accessory, the acetonitrile will
decompose to acetate and ammonium in the strong basic environment of the cartridge. Acetate ions will exchange onto the Cation
AutoRegen Regenerant Cartridge and severely limit its lifetime. Solvents other than acetonitrile have no effect on the cartridge
lifetime.
CAUTION
Acetonitrile decomposes to ammonium acetate when subjected to basic solutions such as the 0.1 M
tetrabutylammonium hydroxide (TBAOH) used as the regenerant solution in the AutoRegen Cation Regenerant
Cartridge. The acetate ion exchanges onto the AutoRegen Cation Regenerant Cartridge. If high levels of
acetonitrile are used in the eluents, the cartridge can become expended within a few hours. A pressurized
regenerant delivery system should be used as an alterative.
When replacing the recycled regenerant, the first 200 mL of the regenerant should be pumped to waste before recycling of the
regenerant is started. Utilizing AutoRegen in this manner will allow the use of high regenerant flow rates with the minimum of
consumption and waste.
3.7.1 ASRS ULTRA II in MPIC Suppression or Chemical Suppression Mode
To save regenerant preparation time, consumption, and waste, it is recommended that the AutoRegen Accessory (115 V ac version,
P/N 039594; 230 V ac version, P/N 039608) be purchased. The AutoRegen Accessory should be equipped with an Anion
AutoRegen Regenerant Cartridge (P/N 039564). For detailed information on the operation of the AutoRegen Accessory, see
Document No. 032853. For detailed information on the use of the AutoRegen Regenerant Cartridge, see Document No. 032852.
However, when using an AutoRegen Accessory, it is necessary to replace the regenerant on a regular basis. How often the
regenerant is replaced will depend on the application and the concentration of solvent in the eluent. Minimally, the regenerant
should be replaced once a week. It is not necessary to change the AutoRegen Regenerant Cartridge until it is completely expended.
Solvent, much like the TBA + ions, passes through the membranes of the ASRS ULTRA II suppressor from the eluent into the
regenerant stream. The solvent and the TBA + ions are carried from the suppressor to the regenerant reservoir by means of the
