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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: jvm208 on January 14, 2017, 01:42:39 AM

Title: HPLC mobile phase question
Post by: jvm208 on January 14, 2017, 01:42:39 AM

Could someone please explain why retention would increase as the acetonitrile
portion of the mobile phase increases in HPLC?

Would this apply to non-polar analytes?

Thank you.

Title: Re: HPLC mobile phase question
Post by: Dan on January 14, 2017, 07:38:21 AM

Quote from: jvm208 on January 14, 2017, 01:42:39 AM

Could someone please explain why retention would increase as the acetonitrile
portion of the mobile phase increases in HPLC?

Depends on whether the the stationary phase is normal or reverse phase (RP), and it depends on the composition of the mobile phase (what is the other solvent?).

Title: Re: HPLC mobile phase question
Post by: jvm208 on January 15, 2017, 01:31:13 AM

The mobile phase composition is acetonitrile and water (75:25) in reversed phase HPLC

Thank you.