Assuring retention of polar compounds in an Aqueous Normal Phase ANP gradient in positive ion mode LCMS

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Assuring retention of polar compounds in an Aqueous Normal Phase ANP gradient in positive ion mode LCMS - Tips & Suggestions

When using a Cogent TYPE-C™ column such as the Diamond Hydride prepare your solvents for positive ionization in LC-MS:

Solvent A: 50% methanol / 50% DI water + 0.1% formic acid
Solvent B: 90% acetonitrile /10% DI water + 0.1% formic acid.

Aqueous Normal Phase ANP gradients need to start between 100% - 90% of Solvent B (to retain polar compounds) and then reduce the percent of Solvent B as much as 20% solvent B (when 50% methanol / 50% water is used as Solvent A).

One important advantage to note about the Cogent TYPE-C columns is that they equilibrate between gradient runs very fast (5 minutes) compared to HILIC columns which require up to 20-30 minutes or more.

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