Detection of Content and Isotope Abundance of ¹⁵N-S-benzyl-L-cysteine

A HPLC method for determination of S-benzyl-L-cysteine in fermentation broth was established. Cosmosil C18 column(5 μm,150 mm×4.6 mm) was used with 2,4-dinitrofluorobenzene as derivatization reagent and 0.05 mol/L sodium acetate buffer (pH=6.5，including 10 mL/L N,N-dimethylformamide) and V(acetonitrile)∶V(water)=3∶1 as mobile phase. The content was detected at a flow rate of 1.0 mL/min(gradient), the detection wavelength was 350 nm, column temperature was 30 ℃. The calibration curves were linear in the range of 0.2~1.0 g/L(R²=0.998 6), the average recovery rates were 97.30%, the minimum limit was 3.95×10^-4 g/L, the relative standard deviation of results was 0.55%. Microscale high temperature combustion-MS method was also described to detect the isotope abundance of ¹⁵N-SBC. The minimum consumption of ¹⁵N-SBC product was 2 mg, the optimal combustion temperature was 530 ℃ and reaction time was 3 h. The RSD of results was 0.17%.