Determination of Amino Acids in Escherichia Coliª±by Ultrahigh Performance Liquid Chromatography Combined with Hollow Fiber Membrane Microextraction

KeyWord:Escherichia coli.  amino acid  ultra high performance liquid chromatography£¨UHPLC£©  hollow fiber membrane phase microextraction

Abstract:

      A three phase hollow fiber membrane microextraction/ultrahigh performance liquid chromatography£¨HF-LPME/UPLC£© was developed for the determination of eight amino acids in Escherichia coli..The three phase hollow fiber membrane micro extraction system was designed.The extraction conditions for HF-LPME were optimized as follows:the supported liquid membrane:n octanol,the concentration for NaOH in receiving phase:0ª±30 mol/L,the concentration for hydrochloric acid in sample solution:5ª±0 mmol/L,the concentration for NaCl:200 g/L,the extraction temperature:25 ¡æ,the stirring speed:500 r/min and the extraction time:4 hours.Eight kinds of amino acids were extracted after derivatization,and finally analyzed by UPLC.A baseline separation was achieved within 5 min.The calibration curves for the analytes were linear in range of 0ª±20-4ª±9¡Á103 ¦Ìmol/L with their correlation coefficients£¨r2£© more than 0ª±999,the enrichment factors of 110-290 and the detection limits of 0ª±0l/L.At a spiked concentration of 10 ¦Ìmol/L,the recoveries for eight amino acids in Escherichia coli.were 88ª±7%-103ª±1% with the relative standard deviations of 3ª±2%-4ª±3%£¨n=5£©.The proposed method was highly sensitive and reproducible,and could be used for the detection of amino acids in bacteria.