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Some of our products and methods have been acknowledged by USP-PQRI column database. They are
| Sunnist |
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C18 |
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C8 |
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PhE |
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RP-AQUA |
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| SunShell |
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C18 |
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C8 |
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PFP |
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Phenyl(hexyl) |
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RP-AQUA |
About PQRI
The PQRI procedure for choosing an equivalent column that can be substituted for the original column was developed over a 10-year period from 1998 to the present time. 1 2 On the basis of almost 3000 retention-time measurements for 150 different test-compounds and 100 different alkylsilica columns, it was possible to show that five column properties completely account for column selectivity:
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Column hydrophobicity
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Measured by the Column Parameter
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H
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Column steric interaction
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" "
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s*
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Column hydrogen-bond acidity
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" "
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A
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Column hydrogen-bond basicity
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" "
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B
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Column ion-exchange capacity
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" "
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C
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Values of these parameters do not vary much with other column conditions, except that C depends on mobile phase pH. Therefore, it is necessary to specify whether a high-pH or low-pH mobile phase is used for the separation. The USP program allows a choice of pH = 2.8 (low) or 7.0 (high), whichever value is closest to the actual mobile phase pH. Column selectivity for carboxylic acids is measured by the parameter B, while selectivity for basic compounds is measured by C. If it is known that the sample to be separated contains acids, it is necessary to check the "acids present" box in the program. Similarly, if the sample contains bases, the "Bases present" box should be checked. If it is not known whether acids or bases are present in the sample, both boxes should be checked.
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