The Application Of Atmospheric Pressure Gas Chromatography Quadrupole Time-of-Flight Mass Spectrometry For The Analysis Of Pesticide Residues

Gas chromatography has been widely applied for the analysis of pesticide residue detection.Some difficulties have been caused by the tradtional ionization which was relatively hard ionization resulting in more fragment ions,poor characteristic ions and weak quasi-molecular ion and may cause false positives.With the restriction of scan time and dwell time,it is difficult to monitor more than hundreds of compounds by using these traditional techniques.Atmospheric pressure ionization and time of flight mass spectrometry were the newly developed analysis technique in recent years.The soft ionization of atmospheric pressure gas chromatography ionization source has the strong potential in the qualitative and quantitative analysis which provides higher fragmentation of molecular ion and helps to produce high seletivity and sensitivity analysis in the pesticide residue anlysis.Therefore,it is of great research and practical significance to develop and to evaluate atmospheric pressure gas chromatography quadrupole time-of-flight mass spectrometry(APGC-QTOF-MS)and to develop a sensitive,accurate and reliable method for the pesticide detection and screening in environment matrix.Thus,in order to evaluate the application the APGC-QTOF-MS,the quantification and qualitative analysis of analytes were carried out in this paper.The main results are listed as following:1.The comparison of APGC-QTOF-MS and GC-EI-MS on sensitivity was conducted and the results showed higher sensitivity for the analysis of fifteen organochlorine pesticides by using APGC-QTOF-MS which the sensitivity were increased by 7-305 times.The limit of detection was 0.26?g/kg.The residue analysis methods of organochlorine pesticides in soil and water samples were built by using APGC-QTOF-MS.The linearity,accuracy,precision and sensitivity of the method were also investigated.The results showed excellent linearity of the method with all the r~2?0.9931 in soil and samples.The results showed that the mean recoveries for all the pesticides from the soil samples were70.3–118.9%with 0.4–18.3%intra-day relative standard deviations(RSD)and the mean recoveries of water samples were 70.0–118.0%with 1.1–17.8%intra-day RSD which meet the demand for pesticide residue analysis.2.The differentiation of APGC-QTOF-MS and GC-EI-MS on sensitivity was compared.The results showed that the sensitivity were enhanced by 1.0-8.2 times.The limit of detection was 0.13?g/kg.The residue analysis method of fifteen organophosphorus pesticides residues in fruits and vegetables were carried out.The results showed excellent in soil and samples.The results showed that the mean recoveries for all the pesticides in fruits and vegetable samples were 70.0–115.9%with the intra-day relative standard deviations(RSD)less than 19.7%which meet the demand for pesticide residue analysis.3.The application of building a scientific screening library method of organic pollutants employing APGC-QTOF-MS combined with UNIFI scientific information system and a screen for detection and identification of 110 organic pollutants(91 pesticides,13 organic pollutants and 6 plasticizer)in seven fruits and vegetables have been reported.The screening and detection method were developed for the analysis of 110 organic pollutants in fruits and vegetables.The molecular ion or proton ions and the fragment ions were included in this scientific screening library which can be used for the automatic screening of target analytes and resulting in low false positives.Then to further demonstrate the practicality of the screening method and the established library,a total of 42 real samples collected from several areas(The Province of Shanxi,Xinjiang,Gansu,Tianjin,Hebei,Ningxia,Sichuan,Shandong and Beijing)in China were randomly analyzed following the developed procedure for the screening of110 organic pollutants.In total,23 organic pollutants were detected in 42 real samples and difenoconazole,dimethomorph and acetofenate were the most frequently identified pesticides which provided reliability guarantee for the screening of pesticide and organic pollutans due to the reliable characteristic of automatic screening.