An HPLC-MS/MS method was developed for the quantitative determination of 1-deoxynojirimycin (DNJ), a potent glucosidase inhibitor presented in mulberry leaves (Morus alba L.). DNJ was separated from an extract of mulberry leaves on a TSK gel Amide-80 column using a mixture of 0.1% formic acid and acetonitrile as the mobile phase at a flow rate of 0.6 mL/min. A triple quardupole mass spectrometry using turbo spray ionization source in the positive ion mode under multiple reaction monitoring with the [M-H]+ ions, m/z164.4/ 109.9 was used. The detection limit (S/N=3) was 75 pg and quantification limit (S/N=10) was 100 pg. The DNJ was higher in young shoots of mulberry in comparison with young leaves and mature leaves.
