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Eluent Conditions for RSpak D-series

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1. General information
The following factors influence the separation for RSpak D-series columns:
  (a) Composition of the eluent
  (b) pH of the eluent
  (c) Concentration of salt
  (d) Column temperature
Polymer based columns can be used with alkaline conditions. The usable pH range for each column is mentioned in the page of the column specification.
The eluent must not contain salt in a quantity larger than 0.5M.
If the protein is contained in the sample, please remove it from the sample solution by pretreatment.

2. DS-613 and 413
The column is used primarily in reversed-phase chromatography, in which the eluent is a mixed solution of water and a polar organic solvent such as methanol and acetonitrile or a mixed solution of the same components plus salt, acid or base. The analysis conditions of ODS column are helpful in determining the eluent conditions for the RSpak DS-series columns. Generally, it is necessary that the eluent condition of RSpak D-series columns should be a slightly stronger condition in elution than that of ODS column.
Though the packing material both of DS-613 and DS-413 is styrenedivinylbenzene copolymer, the swelling degree for each organic solution is not the same.
The following solvents are usable as the eluent:
(DS-613)
DS-613 cannot be used with 100% water. As a result, the eluent condition should include some organic solution.
If the mixture of acetonitrile and water is used, at least 10% acetonitrile is needed. 100% acetonitrile is usable.
If the mixture of methanol and waters is used, at least 10% methanol is needed. 100% methanol is usable.
If the mixture of THF and water is used, at least 10% THF is needed. And the concentration of THF should be up to 50% in the eluent, if THF is included in the eluent.
The situation of toluene and chloroform is as same as THF, though these two are not mixable with water. So maximum concentration for these organic solutions is also up to 50%.
(DS-413)
DS-413 cannot be used with 100% water as DS-613. As a result, the eluent condition should include some organic solution.
If the mixture of acetonitrile and water is used, at least 10% acetonitrile is needed. 100% acetonitrile is usable.
If the mixture of methanol and water is used, at least 30% methanol is needed. 100% methanol is usable.
And if the mixture of THF and water is used, at least 5% THF is needed. 100% THF is usable.
CAUTION
The eluent must be in pH range of 2.0 to 12.0 for DS-613, and 1.0 to 13.0 for DS-413. If the eluent contains chloride ions, its pH must be 4.0 or higher.

3. DE-613, 413 and 213
The column is used principally in reversed-phase chromatography, in which the eluent is a mixed solution of water and a polar organic solvent such as methanol, acetonitrile, or a mixed solution of the same components plus salt, acid, or base. Although water and polar organic solvents can be mixed together at any ratio, it is necessary to confirm that salt does not precipitate. The analysis conditions of the silica based columns having an octyl functional group are helpful in determining the eluent conditions for the RSpak DE-series columns.
Although DE-613 is not usabe with THF, DE-413 and DE-213 can be used with THF.
CAUTION
(1) Nonpolar organic solvents such as benzene, chloroform and n-hexane must not be used as the eluent.
(2) The eluent must be in a pH range of 2.0 to 12.0. If it contains chloride ions, its pH must be 4.0 or higher.

4. DM-614
A mixture of water and a polar organic solvent such as acetonitrile, methanol and ethanol, or such mixture including some salts is commonly used as the eluent. 100% of aqueous solution is also usable as the eluent. Water and a polar organic solvent can be mixed at any ratio without precipitation of salt. The separation mode is reversed phase under the eluent condition containing higher rate of aqueous solution. This column also works as HILIC mode column under the eluent condition containing higher rate of organic solution. For the separation of organic acids, the retention will be weak under aqueous eluent condition.
In that case, some salts are effective to make the retention stronger as the additive in the eluent. Although water and polar organic solvent can be mixed at any ratio, it is necessary to confirm that salt does not precipitate.
CAUTION
(1) Nonpolar organic solvents such as n-hexane, benzene and chloroform cannot be used as the eluent.
(2) The pH value of the eluent must be in the range of 2.0 to 10.0. In case the eluent contains chloride ions, its pH must be 4.0 or higher.
(3) Do not use any strong acids, strong bases or perchlorates as the eluent.

5. DC-613
The mixture of water and a polar organic solvent such as acetonitrile and ethanol can be used as the eluent. Sodium salt is the only substance that can be added to the eluent.
A mixed solvent of 50/50 to 90/10 acetonitrile/water is used as the eluent for the separation of saccharides. The higher the water content, the earlier the elution of saccharides.
CAUTION
(1)Do not use more than 95% of polar organic solvent in preparation of the eluent; otherwise the packing material will shrink and can cause of the column to deteriorate.
(2) Strong basic sample will be adsorbed to the packing material.
(3) Do not inject any sample containing heavy metal ions; otherwise, Na+ ions of the ion exchange resin will be exchanged to the heavy metal ions, thereby causing the change of column performance. To prevent such ion exchange, EDTA-4Na is added in the amount of 50 to 100 ppm to the eluent to mask the metal ions.

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