| 1 PrefaceIn recent years,ultra-high performance liquid chromatography（UHPLC）technology is an emerging field of rapid development,and has been widely applied to the analysis of various substances.This part concisely recommends the theory,instrument system,characteristics of UHPLC,and the detection technologies combined with UHPLC as well as liquid phase micro-extraction technology principle and its applications.This paper is based on the three-phase hollow fiber membrane liquid-phase micro-extraction technology to purify and enrich the analytes in the actual samples,and then combined with UHPLC-DAD analysis system to detect and analyze them.Finally,this chapter also introduces the research purpose and significance of the paper.2 Determination of six kinds of sulfonamides in chicken by ultra-high performance liquid chromatography with hollow fiber membrane microextractionDevelopment of an analytical method for the determination of chicken meat based on a three-phase hollow fiber membrane microextraction-ultra high performance liquid chromatography（HF-LPME-UHPLC）has been explored.Three-phase hollow fiber membrane microextraction system was designed to optimize the optimum extraction conditions of HF-LPME:the extractant was n-octanol,the concentration of NaOH in receiving phase was 200 mmol/L,the concentration of hydrochloric acid in sample solution was 1.0 mmol/L,the concentration of Na2SO4 was 375 g/L,the extraction temperature was 30℃,the stirring rate was 300 r/min,and the extraction time was 4hours.Chicken meat samples were extracted and analyzed by UHPLC,and chromatographic analysis showed that the six sulfonamides reached baseline separation within 6 min.The linearity of the six sulfonamides in the mass range was good with the correlation coefficient R2>0.998,and the enrichment factors are range from 188 to 950times;the detection limit was 0.03-0.1 ng/mL（S/N=3）.The recoveries of the sulfonamides spiked in chicken were 86.3%-95.6%with the relative standard deviations were 3.13%-4.33%（n=5）at the concentration of 50μg/kg.The studied method is highly sensitive and reproducible,and can be used for the detection of sulfonamides in chicken.3 Determination of amino acids in escherichia coli by ultra high performance liquid chromatography combined with hollow fiber membrane micro-extractionThe determination of eight amino acids in Escherichia coli based on a three-phase hollow fiber membrane microextraction-ultra high performance liquid chromatography（HF-LPME-UHPLC）has been explored.Three-phase hollow fiber membrane microextraction system was designed and the extraction conditions of HF-LPME was optimized:the extractant was n-octanol,the concentration of NaOH in receiving phase was 0.3 mol/L,the concentration of hydrochloric acid in sample solution was 5.0 mmol/L,the concentration of NaCl in sample solution was 200 g/L,the extraction temperature was 25℃,the stirring speed was 500 r/min,and the extraction time was 4 hours.Eight kinds of amino acids were extracted and analyzed by UHPLC,and a baseline separation was achieved within 5 min.The linearity of the eight amino acids in the mass range was good with the correlation coefficient R2>0.999,the enrichment factors are range from 110 to 290,and the detection limits were in the range of 0.08-0.35μmol/L（S/N=3）.The recoveries of the eight amino acids spiked in E.coli were 89.61%-102.74%with the relative standard deviations ranging from3.15%to 4.28%（n=5）at the spiked concentration of 10μmol/L.The studied method was highly sensitive and reproducible,and could be used for the detection of amino acids in bacteria.4 Determination of short-chain fatty acids in Escherichia coli fermentation by ultra-high performance liquid chromatography combined with hollow fiber membrane micro-extractionThis experiment explored a three-phase hollow fiber membrane microextraction-ultra high performance liquid chromatography（HF-LPME-UHPLC）method for the determination of six short-chain fatty acids produced by E.coli fermentation.A three-phase hollow fiber membrane microextraction system was designed and the extraction conditions of HF-LPME was optimized.The extractant was n-octanol,the concentration of NaOH in the receiving phase was 1.0×10-4 mol/L,the concentration of hydrochloric acid in sample solution was 0.06 mmol/L,the extraction temperature was 25°C,the stirring speed was 400 r/min,and the extraction time was 60 minutes.Six kinds of short-chain fatty acids were extracted and then chromatographed by UHPLC.The baseline separation was achieved within 6 min.The linear relationship was pretty good.R2 was greater than 0.999.The enrichment factor was 95-146 times and the detection limit was 0.26-1.33μmol/L（S/N=3）.The spiked recoveries were86.07%-95.51%in samples with a 10μmol/L spiked concentration of E.coli and the relative standard deviations were 3.01%-4.29%（n=5）.The experimental results told that the method had high sensitivity and reproducibility,and could be used for the detection of short chain fatty acids produced in E.coli fermentation. |
