HPLC analysis was conducted on an Agilent 1200 series HPLC
(Agilent Technologies, Santa Clara, CA) fitted with an Agilent Eclipse
XDB-C18 (150 mm 4.6 mmi.d.; 5 lmparticle size) columnwith a
C18 guard column (Phenomenex, Macclesfield, UK). Mobile phase
flow rate was 1 ml/min at 30 C using a 25 mM phosphate buffer/
methanol mixture. Phosphate buffers of pH 6 were used for riboflavin
and pH 7 for both amino acids and peptides. Detection was at
210 nm for the amino acids and peptides and 270 nm for riboflavin.
Injection volumes of 10 ll for amino acids and peptides and 20 ll
for riboflavin were used. Mobile phase (buffer:methanol) ratios of
93:7, 60:40 and 50:50 v/v were used for analysis of the amino acids,
riboflavin and peptides respectively.