Determination of Streptomycin and Dihydrostreptomycin in Vegetable Foods by High Performance Liquid Chromatography-Tandem Mass Spectrometry with Solid Phase Extraction

KeyWord:vegetable foods  streptomycin  dihydrostreptomycin  HPLC-MS/MS

Abstract:

      A method was established for the determination of streptomycin(STR) and dihydrostreptomycin(DHS) in vegetable foods(apple,celery,capsicum and lentil) based on high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS).The sample was extracted with phosphate buffer and cleaned up with a WCX solid phase extraction cartridge.The extracts were separated on an Atlantis Hilic Silica column(100 mm¡Á3ª±0 mm,3 ¦Ìm) using acetonitrile-0ª±1 mol/L ammonium formate and 0ª±1% formic acid as mobile phases by isocratic elution,then detected by HPLC-MS/MS in positive ion mode under multiple reaction monitoring(MRM) mode.An external standard method was used for quantitative analysis.The calibration curves for streptomycin and dihydrostreptomycin showed good linearity in the range of 10-120 ¦Ìg/L with their correlation coefficients(r) more than 0ª±999.The limits of quantitation(LOQs) were both 125 ¦Ìg/kg.The average recoveries for streptomycin and dihydrostreptomycin at three spiked levels of 125,250 and 500 ¦Ìg/kg ranged from 83ª±6% to 101%,with the relative standard deviations(RSDs) of 2ª±3%-7ª±6%.With no need of ion pair reagents resulting in the contamination of liquid chromatography-mass spectrometer,the method is simple,rapid,reliable and stable,and could meet the requirements for determination of streptomycin and dihydrostreptomycin residues in most vegetative samples.