The HPLC system (Shimadzu) was comprised of a model LC-10A
pump, a Rheodyne injection valve with a 20 ll injection filling
loop, and a model RF535 fluorescence spectrophotometer operating
at an excitation wavelength of 330 nm and an emission wavelength
of 375 nm. The HPLC column was a Reliasil ODS-1 C18
column (5 lm packing material) with 250 4.6 mm i.d. The
mobile phase was 30% water and 70% acetonitrile, containing
1 ml/l acetic acid and 1 ml/l o-phosphoric acid. The NPM derivatives
were eluted from the column isocratically at a flow rate of
1 ml/min. Quantitation of the peaks from the HPLC system was
performed with a Chromatopac, model C-R601 (Shimadzu).