The HPLC-method used a C18 column with a dual gradient elution. Solution A was 0.1% formic acid in H2O and solution B was 0.1% formic acid in acetonitrile. The elution protocol started with 75%A and 25%B changing to 70%A and 30% B over 7 minutes. Then the solution changed to 58%A and 42%B over 3 minutes. Detection was fluorescence based using 488nm excitation and 555 nm emission wavelengths.