Ammonium acetate, ammonium formate or ammonium hydroxide
typically find use in mobile phases for analysis of PFC. In
this study, most of PFC showed best responses in methanol containing
neither buffers, nor acids. Nevertheless, the peak shapes of
PAP, PFAPA and late eluting PFCA were notably distorted. The
addition of ammonium acetate substantially improved the peak
shapes and provided still acceptable responses as documented in
Fig. 6 which made this composition a good choice for the final
method.