Study Of Dispersive Liquid-liquid Microextraction-chromatography-mass Spectrometry Detection Methods Of Pesticide Residues In Food

Pesticide residues of food had been affected the human health by food chains.It was very important to build the simple and effective detection methods.Dispersive liquid-liquid microextraction(DLLME)was a new kind of pretreatment method,which advantages are low organic solvent consumption,simple operation,high enrichment factor and sensitivity.This paper used the dispersive liquid-liquid microextraction as pretreatment.In order to reduce the influence of matrix effectively,it detected pesticide residues in food with gas chromatography mass spectrometry(GC-MS/MS)and liquid chromatography mass spectrometry(LC-MS/MS).The main research contents and results were as follows:1.Using salting-out and vortex assited DLLME-GC-MS/MS detected 8kinds of amide herbicide residues in food,exploreding the GC-MS/MS and the optimition condition of DLLME.The types and volumes of dispersive solvent and extraction solvent,vortex time,ionic strength and centrifugal time was optimized.The best conditions were: dispersive solvent was 9.5 mL of acetonitrile,extraction solvent was 30 ?L bromobenzene,vortex time was5 s,the centrifugal time was 6 min.The limit of detection range were 0.03~0.6 ng/L,limit of quantitative were 1.0 ng/L,the correlation coefficient were over 0.992,the enrichment ratio were 3480 ~ 3920,relative standard deviations were below 9.6%,the recovery of 250 ng/L ? 750 ng/L adding samples were 87 ~ 103%.This method had high extraction efficiency and repetition rate,that suited for vegetables tea pesticide residue analysis.2.The salting out and vortex assited DLLME-LC-MS/MS method to determined the 6 kinds of organophosphorus residues in tea and fruit juice.Methanol and water were mobile phase(containing 0.1% formic acid).Detection was in the positive ion mode by multiple reaction monitoring and external standard method of quantitative analysis.The volumes and types of dispersive solvent and extraction solvent,vortex time,and ionic strength conditions were optimized.The best conditions: 7.5 mL n-propanol wasdispersive solvent,30 ?L 1-bromine-3-methyl-butane was extraction solvent,0.5 g NaCl was added,the first vortex time was 2 min,the second vortex was50 s.The limit of detection range were 10~25 ng/L,the limit of quantitative were 50.0 ng/L,the correlation coefficient were over 0.990,the enrichment ratio were 3640~4120,relative standard deviations were below 10.6%,the standard addition(200?800 ng/L)recovery rate were 85~107%.It was a simple and rapid method of pesticide residue analysis.3.Building a ?-solid phase extraction-DLLME-LC-MS/MS detected 4kinds of pesticides in tea and fruit juice analysis method.Acetonitrile and water were mobile phase(containing 0.1% formic acid),the method was in the positive ion mode by multiple reaction monitoring and external standard method of quantitative analysis.Experiment using metal organic frameworks(MOFs)as solid phase extraction adsorbents,reducing the influence of the substrate.Experiments mainly from the varieties and amount of MOFs,extracting agent?the varieties and amount of dispersant and vortex time to optimize the experimental conditions.The best conditions: 150 mg of MIL-100(Fe),acetonitrile was the elution agent and dispersant,1.3 mL/time,elution 3 times,40 ?L bromobenzene was extraction agent,vortex time was50 s.The limit of detection range were 0.3 ~ 0.6 ng/L,the limit of quantitative were 1.0 ng/L,the correlation coefficients were over 0.993,the enrichment ratio were 890 ~ 990,relative standard deviations were below9.3%,standard addition(250?750 ng/L)recovery rates were 88~103%.Low organic solvent consumption and less influence matrix were suitable for more complex matrix of pesticide residues in food detection.