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NMPA is an acronym you know very well, but it is used for several different chemical components. Please post the real name(s) or even structure(s) so the community might be able to help.
Anyway, there is no magical function to transform normal phase (NP) into reversed phase (RP) conditions. You typically use RP when the hydrophobicity (log P) of a molecule is greater than 1.5, i. e. it will have retention on C18 phases (or other). Below 1.5 NP is the technique to use as polar interactions rule. And then there is HILIC, a kind of aqueous normal phase technique. But all depends on the chemical structure of the analyte.