Normal phase solvents order of polarity:
hexane > dichloromethane > chloroform > isopropanol>ethanol, etc.

Reversed phase solvents order of hydrophobicity:
buffers > water > methanol >  acetonitril > ethanol > isopropanol

---

REVERSED PHASE to  NORMAL PHASE

waters ->  methanol  -> isopropanol -> hexane

1. Remeber: H2O, ACN, MeOH do not mix with hexane!  Do not keep any normal phase solvent in the reservoirs when working with reversed phase solvents! 2. Isopropanol (IPA) mixes with hexane or with H2O, ACN, MeOH When finishing with reversed phase solvents always wash the entire system with H2O: pump-autosampler-detector-sealwash and needlewash with H2O to remove residues of buffers.  Use a zero-dead-volume-union instead of the column. Wash with MeOH: minimum of 10 ml should pass through each line A, B, C, D, and through the injector (Purge injector) and through the detector (just use the flow). Wash with IPA: minimum of 10 ml should pass through each line A, B, C, D, and through the injector (Purge injector) and through the detector (just use the flow). Only after the entire system is flushed with IPA you can introduce normal phase solvents such as hexane and chloroform.

---

NORMAL PHASE to  REVERSED PHASE

hexane -> isopropanol -> methanol -> waters

1. Remeber: H2O, ACN, MeOH do not mix with hexane! 

• Do not keep any of those polar solvents in the reservoirs when working with normal phase solvents!

2. Isopropanol (IPA) mixes with hexane AND with H2O, ACN, MeOH

• Always keep isopropanol as a reservoir when working with normal phase solvents, it will be used as the final wash solvents to the entire HPLC system.

• When finishing with normal phase solvents always wash the entire system: pump-autosampler-detector-sealwash and needlewash with Isopropanol. Use a zero-dead-volume-union instead of the column if needed.

• Wash with IPA: minimum of 10 ml should pass through each line A, B, C, D, and through the injector (Purge injector) and through the detector (just use the flow).

• Wash with MeOH: minimum of 10 ml should pass through each line A, B, C, D, and through the injector (Purge injector) and through the detector (just use the flow). 

• Wash with H2O: minimum of 10 ml should pass through each line A, B, C, D, and through the injector (Purge injector) and through the detector (just use the flow).

• Only after the system was washed with H2O it is ready for reversed phase.