Rinsing Columns for Ion Chromatography
In responses to frequent inquiries, this page describes the rinse method for columns used for ion chromatography and the corresponding precautions.
Rinsing a column used for ion chromatography mainly targets removal of polyvalent ions and organic compounds. Using ions with high elution capacity or increasing the ion concentration is effective for rinsing off polyvalent ions. Conversely, an aqueous solution containing an organic solvent is effective for rinsing off organic compounds. However, the concentration is restricted according to the column used.
Note: The rinse method shown here is not guaranteed to recover the column performance.
(1)Shared Items
Read the shared items, regardless of the column used.
(2)Shim-pack IC-A1
(3)Shim-pack IC-A3
(4)Shim-pack IC-SA2/SA3
(5)Shim-pack IC-C1
(6)Shim-pack IC-C3
(7)Shim-pack IC-SC1
(8)Shim-pack IC-C4
(1) Shared Items Read, regardless of the column used.
Methods, Flowrate, Time
- Rinse the column by pumping liquid with the pump. However, only when alkali metals are analyzed using IC-C1, rinsing can be performed by repeatedly injecting rinse solution from the injector while pumping eluent.
- Unless otherwise specified, use approximately half the normal analysis flowrate or 0.5 mL/min for rinsing. The column pressure may increase, according to the type of column contamination and rinsing solution. In this case, reduce the flowrate so that the pressure does not exceed the pressure during normal operation.
- Unless otherwise specified, use a rinsing time of 1 to 2 hours.
Rinsing the Guard Column
The rinse methods for analysis columns described below can also be directly applied to the corresponding guard columns. However, this can be counterproductive due to accumulated material on the guard column which can contaminate the analystical column when rinsed out of the guard column. Therefore, you are recommended to rinse the analytical column and guard column separately.
Suppressor Method
To prevent the column rinse solution from flowing into the suppressor, take appropriate measures such as connecting a direct pipe from the column outlet to the drain bottle before rinsing using the suppressor method.
For the same reason, pass eluent through the column after rinsing to wash out all rinse solution before connecting the suppressor.
Liquid Direction Through the Column
Generally, pass rinse solution through the column in the "normal" direction used during analysis. Pumping rinse solution in the "reverse" direction can result in deterioration in the column performance.
However, as contaminants normally accumulate near the inlet of the column, effective rinsing is sometimes achieved by pumping the rinse solution in the reverse direction from the flow direction during analysis. Note that pumping the rinse solution in the "reverse" direction can significantly change the state of the column packing and cause deterioration in column performance. (Except in cases where rinsing in the reverse direction is explicitly specified in the operation manual.)
Effects of Column Rinsing
Perform column rinsing only when necessary. Using a rinse solution with a different composition too often may change the properties of the packing, resulting in reduced performance and increased pressure.
Liquid in Column During Storage
Storage up to 1 month: Fill the column with the mobile phase used for analysis.
Storage for more than 1 month: Replace the mobile phase in the column each month
(2) Shim-pack IC-A1
| Rinse solution 1 Contamination by polyelectrolytes |
120 mM aqueous solution of potassium hydrogen phthalate |
| Rinse solution 2 Contamination by hydrophobes |
Mixture of aqueous solution containing 2.5 mM phthalic acid and 2.4 mM tris(hydroxymethyl)aminomethane with acetonitrile (9/1, v/v). (Methanol can be used instead of acetonitrile.) |
| Organic solvent concentration | 10 % max. of methanol or acetonitrile |
| Restrictions on use (IC-A1) | pH = 2 to 11, pressure < 5 MPa (normally 2 MPa), temperature < 50 °C |
(3) Shim-pack IC-A3 Precautions
| Rinse solution 1 Contamination by polyelectrolytes |
120 mM aqueous solution of potassium hydrogen phthalate |
| Rinse solution 2 Contamination by hydrophobes |
Mixture of aqueous solution containing 8.0 mM p-hydroxybenzoic acid and 3.2 mM bis-tris with acetonitrile (1/1, v/v). (Methanol can be used instead of acetonitrile.) |
| Rinse solution 3 Final remedy if pressure rises or retention times decrease. |
Mixture of 20 mM phosphoric acid (sodium) buffer solution (pH 2.5) containing 100 mM sodium perchlorate with ethanol (1/2, v/v). Reverse connections before pumping rinse solution. Details on rinse method |
| Organic solvent concentration | 70 % max. of ethanol, methanol, or acetonitrile |
| Restrictions on use | pH = 3 to 8.5, pressure < 12 MPa (normally 8 MPa), temperature < 50 °C (normally 40 °C) |
| Enclosed liquid | Fill with 70 % aqueous solution of ethanol for long-term storage. Fill with mobile phase for normal storage. |
(4) Shim-pack IC-SA2, IC-SA3
| Rinse method 1 For F tailing or decreased PO4 |
Pump mixed solution of 20 mM EDTA-2Na aqueous solution* and acetonitrile (10/1, v/v) for 12 hours. (Subsequently, pump the mobile phase used for analysis at 0.5 mL/min for 15 minutes and at the analysis flowrate for approximately 2 hours before connecting the suppressor. ) * EDTA-2Na aqueous solution: Aqueous solution of disodium ethylenediaminetetraacetate |
| Rinse method 2 Contamination by hydrophiles (polyelectrolytes) |
Mobile phase solution at 10× salt concentration (Subsequently, pump the mobile phase used for analysis at 0.5 mL/min for 1 hour before connecting the suppressor.) |
| Rinse method 3 Contamination by hydrophobes |
Pump 5 % acetonitrile for 10 minutes and 100 % acetonitrile for 1 hour. (Take care, as column pressure may rise.) (Subsequently, pump purified water at 0.5 mL/min for 30 minutes and mobile phase at 0.5 mL/min for 1 hour before connecting the suppressor.) |
| Important points | Disconnect the suppressor when following any of the procedures above. Blockage may occur if EDTA flows into the suppressor. |
| Restrictions on use | pH = 3 to 12, IC-SA2: pressure < 12 MPa (normally 5 MPa), temperature < 60 °C (normally 30 °C) IC-SA3: pressure < 15 MPa (normally 11 MPa), temperature = 20 to 60 °C (normally 45 °C) |
| Enclosed liquid | IC-SA2: Aqueous solution of 1.8 mM sodium carbonate/1.7 mM sodium hydrogen carbonate IC-SA3: Aqueous solution of 3.6 mM sodium carbonate |
(5) Shim-pack IC-C1
| Rinse method 1 Alkali metal analysis (mobile phase: 5 mM nitric acid) |
Inject 1 M nitric acid from the injector while pumping eluent. Inject repeatedly to a total volume of 0.5 to 1 mL.Note 1) |
| Rinse method 2 Other analysis conditions |
Pump 20 mM ethylenediamine / 40 mM tartaric acid mixed aqueous solution. |
| Organic solvent concentration | 10 % max. of methanol or acetonitrile |
| Restrictions on use | pH = 2 to 11, pressure < 5 MPa (normally 2 MPa), temperature < 50 °C |
| Note 1) | Take care with this operation. 1 N nitric acid remaining in the flow line can lead to corrosion. For example, rinse the syringe and injection port thoroughly with purified water after injecting the acid. With a manual injector, load the 1 N nitric acid and immediately inject it. Thoroughly replace the contents of the loop with mobile phase at the injection position. |
(6) Shim-pack IC-C3
| Rinse solution 1 Contamination by polyelectrolytes |
100 mM phosphoric acid (sodium) buffer solution (pH = 2.1)Note 2) |
| Rinse solution 2 Contamination by hydrophobes |
Mixed solution of 2.5 mM oxalic acid and acetonitrile (1/1, v/v)Note 3) (Methanol can be used instead of acetonitrile.) |
| Organic solvent concentration | 70 % max. acetonitrile (Do not use high-concentration ethanol or 2-propanol.)Note 3) |
| Restrictions on use | pH = 2 to 5, pressure < 12 MPa (normally 5 MPa), temperature < 50 °C (normally 40 °C) |
Enclosed liquid |
2.5 mM oxalic acid aqueous solution |
| Note 2) | Dissolve 7.8 g sodium dihydrogen phosphate dihydrate (MW: 156.01) and 3.4 mL phosphoric acid (85 %) in water and make up to 1000 mL.td> |
(7) Shim-pack IC-SC1
| Rinse solution | Mixed solution of 20 mM EDTA-2Na aqueous solution and acetonitrile (20/1, v/v). |
| Important points | Before and after pumping rinse solution, pump approximately 5 mL water. |
| Organic solvent concentration | 5 % max. of methanol or acetonitrile |
| Restrictions on use | pH = 1 to 11 (preferably 2 to 9), pressure = 7 MPa max. (normally 4 MPa), temperature = 50 °C max. (normally 30 °C) |
| Enclosed liquid | 3.5 mM aqueous solution of sulfuric acid |
(8) Shim-pack IC-C4
| Rinse method 1 Contamination by hydrophiles (polyelectrolytes) |
Pump 1 mL ultrapure water, 50 mL mixed solution of 20 mM EDTA-2Na aqueous solution and acetonitrile (20/1, v/v), and 1 mL ultrapure water sequentially at 0.5 mL/min through the column in the normal direction (volumes are approximate guidelines). * Aqueous solution of disodium ethylenediaminetetraacetate |
| Rinse method 2 Contamination by hydrophobes |
Pump 50 mL mixed solution of eluent and organic solvent (acetonitrile or methanol) (9/1, v/v) at 0.5 mL/min through the column in the normal direction. |
| Restrictions on use | pH = 2 to 9, pressure = 6.5 MPa max. (normally 4.5 MPa max.), temperature = 50 °C max. (normally 40 °C), flowrate = 1.2 mL/min max. (normally 1.0 mL/min) |
| Enclosed liquid at shipment | 2.5 mM oxalic acid aqueous solution |