“Signal-to-Noise” Ratio can often be improved by using Aqueous Normal Phase (ANP) Methods in LCMS instead of Reversed Phase (RP) Methods. This results in improved Limits of Detection for a Method making it more “Sensitive”.

The simple reason is that Mass Spec is a Gas State Method and it is easier to fully and quickly Evaporate Organic Solvents used in ANP than Water which is the dominant Solvent in Reversed Phase.  Hence better Signal to Noise or in the vernacular, better Sensitivity.