Q13. How do I wash columns?

1. Eliminate buffer, salt or acid from the column:
   Wash the column with the current mobile phase without buffer, salt or acid for 10-15 min.
   (E.g., for a mobile phase of methanol : 20 mmol/l phosphoric acid buffer = 50 : 50, wash with methanol : water = 50 : 50)
   If the ratio of organic solvent and water is changed, salt may precipitate.
2. Wash impurities in a column to achieve a stable base line:
   Use a solvent with strong elution properties in which the sample dissolves well.

   Type		Usable Solvent / Additive
   Reversed Phase		Sample is not protein Methanol and/or tetrahydrofuran Cleaning Solution Kit for Reversed Phase HPLC Columns (Product No. 08966-30) Sample is protein 50-70% acetonitrile in water containing 0.1% trifluoroacetic acid. Caution: Some proteins may precipitate when concentration of organic solvent is high.
   Normal Phase		Methanol, tetrahydrofuran, ethanol
   Column for Fullerene Separation		1,2,4-trichlorobenzene and others
   Sugar-D, NH2, HILIC		Acetonitrile : water = 50 : 50 * Sugar-D and HILIC can be washed with 100% water.
   SFC		After completing analysis, wash the column with acid- and base-free mobile phase first, then with methanol or ethanol. Store the column with caps tightly plugged.

   Do not use alkaline solutions (pH 7.5 or higher), as they dissolve silica gel. Do not use strongly acidic solutions (pH 1.5 or lower), as they may cleave the bonded phase.

3. Eliminate impurities clogging the column inlet: Pump solvent through in the reverse direction at half the flow rate of regular analysis.
   Caution:
   Disconnect column from the detector during washing. Doing this frequently may disrupt the packing and damage the column. Filter samples and use a guard column to prevent problems like this.
4. If column pressure is high, please refer to Technical Information, Troubleshooting for Increased Pressure (PDF 568 KB)

Q14. How do I store columns?

1. Short-term
   Wash the column with the current mobile phase without buffer, salt or acid for 10-15 min. (E.g., for a mobile phase of methanol : 20 mmol/l phosphoric acid buffer = 50 : 50, wash with methanol : water = 50 : 50)
   COSMOGEL IEX can be stored with a 20-50 mmol/L buffer solution (pH 4.5-9.5).
2. Long-term (one month or longer)
   In addition to the above, replace solvent with the following to avoid fungus, drying, and/or deterioration of column.

Store tightly plugged columns in a cool, dark place where they will not fall or be bumped.

Q15. How long does a column last?

Column lifetime varies depending on the operation conditions (sample, mobile phase, buffer, pH, temperature, etc.). The most common cause of a short column lifetime is inadequate sample treatment. Please refer to Technical Information, Sample Pretreatment for HPLC (PDF 1,090 KB)