In reversed-phase liquid chromatography, which description best represents the typical stationary/mobile phase relationship?

In reversed-phase liquid chromatography, which description best represents the typical stationary/mobile phase relationship?

• A. Nonpolar stationary phase with polar mobile phase
• B. Polar stationary phase with nonpolar mobile phase
• C. Polar stationary with polar mobile
• D. Nonpolar stationary with nonpolar mobile

Answer: (A)

In reversed-phase chromatography, the stationary phase is nonpolar and the mobile phase is polar. This setup uses hydrophobic interactions to retain nonpolar parts of analytes on the nonpolar surface, so more hydrophobic compounds are held longer while polar compounds elute earlier as they dissolve readily in the polar mobile phase. The polar mobile phase also allows finer control of retention by adjusting its composition (for example, increasing organic content to boost elution strength and shorten retention times). Therefore, the typical relationship is nonpolar stationary with a polar mobile phase. The other combinations would describe normal-phase or different retention mechanisms and do not reflect the standard reversed-phase approach.

In reversed-phase chromatography, the stationary phase is nonpolar and the mobile phase is polar. This setup uses hydrophobic interactions to retain nonpolar parts of analytes on the nonpolar surface, so more hydrophobic compounds are held longer while polar compounds elute earlier as they dissolve readily in the polar mobile phase. The polar mobile phase also allows finer control of retention by adjusting its composition (for example, increasing organic content to boost elution strength and shorten retention times). Therefore, the typical relationship is nonpolar stationary with a polar mobile phase. The other combinations would describe normal-phase or different retention mechanisms and do not reflect the standard reversed-phase approach.