Is this separation normal phase or reversed phase? oragano pesticides with a cyano stationary phase and a hexane/methylene chloride mobile phase Normal Phase Reverse Phase Is this separation normal phase or reversed phase? phthalates with an amino stationary phase and a hexane/ethanol mobile phase? Reverse Phase Normal Phase In RP separations, which is the strong solvent water or methanol? methanol O water What would be appropriate pH range(s) for the analysis of butanoic acid pKa 4.8 to ensure reproducibility? Between 2.8 and 6.8 4.8 Above 6.8 Below 2.8 What would be appropriate pH range(s) for the analysis of butanoic acid pKa 4.8 to ensure reproducibility and highest retention? Between 2.8 and 6.8 Below 2.8 Above 6.8 4.8