Hello

I analysed sorbic acid and benzoic acid in wines using HPLC.
Between those two peaks, appears another peak, but I don't know what analyte is this. Please, could someone help me?

Mobile phase:
70 % acetate amonium buffer (0,4 g/L) pH 4,5 (ajusted with acetic acid)
30 % acetonitrile

wave lenght = 254 nm

The samples are diluited 10 x.

column C18

Thank you!