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Column Storage
Top of Liquid Chromatography Q&A
Q1
Q2
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Q7
  Q8
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  Q10
Q1
How should a reversed phase column be stored?
A1
If you are not using the column for one or two days, it is recommended to keep the flow at a reduced rate. For medium-term storage (several days to about one month), seal the column without rinsing unless the mobile phase is harsh acid or alkali and keep it where the temperature does not change greatly. For long-term storage (several months to about one year), store the column after replacing the mobile phase with one containing at least 50% organic solvent. (If the mobile phase is NH2, replace it 100% with CH3CN when storing the column.)
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Q2
How should an ion exchange column be stored?
A2
An ion exchange column is usually stored with a mobile phase. There is no problem if the storage period is about two weeks. For long-term storage of over one month, replace the mobile phase with buffer solution containing neutral organic solvent. The buffer solution may contain salts if they are neutral and about 20 to 100 mmol/L
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Q3
How should the carbohydrate analysis column SUCREBEAD I be stored?
A3
Replace the mobile phase with 1 mol/L NaOH and seal the column for storage.
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Q4
What will happen if the column deteriorates?
A4
Since silica support is dissolved when deteriorated by alkali, peak leading and peak splitting by void are seen. Deterioration by acid may reduce retention by losing alkyl groups. Deterioration by the contamination of packing materials may reduce retention, break the peak shape, increase the column pressure, and reduce separation efficiency.
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Q5
The number of theoretical plates is decreasing. Is there any problem?
A5
The column can be used with no problem provided the decrease does not affect separation or measurement. If the number of theoretical plates is remarkably low, the column may be aged, in which case it should be replaced.
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Q6
For the periodic management of column performance, what management items should be set?
A6
For periodic management, test the column under the same conditions as the column report delivered with the column. The test items are the naphthalene retention time, the number of theoretical plates, the peak shape, and the pressure. Set the level according to the needs of your applications. For the tests, it is recommended to use the same LC system for measurements wherever possible. The results slightly differ depending on the LC system.
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Q7
How can a column packing fault be identified?
A7
Analyze the fault under the same conditions as the column report delivered with the column by measuring the naphthalene retention time, the number of theoretical plates, the peak shape, and so on. If the result is remarkably different from that given in the column report (slight differences between instruments), the packing condition may be faulty. Contact Shiseido.
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Q8
What is the standard column life?
A8
The column life varies with the concentration of organic solvent, the type and concentration of salt, the acid type, pH, and so on. In general, an alkali mobile phase shortens the column life. The life is also shortened if the ratio of organic solvent is 10% or less, especially if the mobile phase is alkali with 100% buffer solution, if a salt containing boracic acid ions or halogen (excluding sodium perchlorate) is added, or if a surfactant like an ion-pair reagent is added. Note that organic bases like triethylamine make the life shorter than inorganic bases. This is true also if an acidic mobile phase is used. When using trifluoroacetic acid for protein analysis, for example, set the concentration of the initial organic solvent to 10% or higher for a gradient system wherever possible. Starting from 0% (100% water) imposes load on the column.
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Q9
What will the column life be in pH10 or stronger alkali?
A9
At pH11 where the hydroxide ion concentration is 10 times greater than that at pH10, for example, the life will be reduced to about a tenth or less, although this depends on the temperature, organic solvent content, and other conditions.
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Q10
We are analyzing proteins. What will the column life be?
A10
We cannot say specifically because the column is greatly affected by the conditions of analysis and the sample matrix. If the initial CH3CN concentration is 10% or less at a gradient, for example, the life will be extremely short because alkyl groups are easily detached by TFA. In case of a gradient, retention tends to become small because increasing the acetonitrile concentration causes the elution of alkyl groups. If the retention has become remarkably low, replace the column. Top of Liquid Chromatography Q&A.
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