The Study Of Detection Technique Using Extractive Electrospray Ionization Mass Spectrometry

Ambient mass spectrometry(AMS),which can be used for rapid analysis of analytes in ambient environment without sample pretreatment,have been developed over a decade.It provides effective approach for online analysis of complex samples.Extractive electrospray ionization mass spectrometry(EESI-MS)is a typical AMS technique which is suitable for a variety of samples.And this technique has been applied to various research fields including biomedical analysis,public security,food safety and so on.This paper characterized EESI-MS for rapid analysis of various samples.The main content includes:1.The commercial ESI-TOFMS has been transformed into EESI-TOFMS,and parameters including electrospray voltage,spray flow rate,sampling carrier gas flow rate,dry gas flow rate have been optimized.Moreover,ion transport voltages in TOFMS were also optimized.For gaseous samples,direct sampling and diffused sampling were applied.For solid samples,in particularly water-containing biological sample,laser ablation(LA)devices have been used.A qualitative analysis method was also developed for preliminary identification of analytes.First,the ion charge number can be established,the accurate m/z value and isotopic pattern can be used for calculation of the ion formula.Then,compounds which followed this ion formula were selected out.Finally,collision induced dissociation(CID)analysis using QTOFMS was performed to show the fragmentation of this substance.The compound can be identified by comparing fragment spectra with that in database and in previous references.2.Online analysis of two kinds of gaseous samples including human exhaled breath and disposable syringe residual volatiles using EESI-QTOFMS.A total of 21 components were found in exhaled breath,and 4 of them were observed for the first time.By comparing mouth exhaled breath with nose exhaled breath,11 nitrogen-containing compounds showed significant difference.Further investigation was performed through mouth exhaled breath after gargling and drinking pure water.The results showed that these nitrogen-containing compounds are from oral cavity and pharynx,and 7 of these nitrogen-containing compounds are endogenous metabolites.It was found that nitrogen-containing compounds have strong ion suppression effect on acetone,which is a metabolite from alveolar breath.This result demonstrates that cleaning the oral cavity and pharynx is necessary before breath test.Online analysis of residual volatiles in disposable syringe with different brands and volumes was also performed.And 10 ions with relatively high intensity were identified.which include dibutylformamide,benzothiazole,4-hydroxy-4-methyl-5-hexenoic acid gamma lactone,diethyl urea,4-vinyl-1-cyclohexene,ethylbenzene,cyclohexanone,morpholine,dimethyl sulfoxide and dimethylformamide.The result showed that disposable syringe with different brands followed different content of benzothiazole,4-vinyl-1-cyclohexene,morpholine in characteristic mass spectra.And syringe with larger volumes would release more volatiles including benzothiazole,cyclohexanone,morpholine and dimethylformamide.Semi-quantitative analysis of cyclohexanone in disposable syringe was also performed,and the LOD is calculated to be 0.13 ?g·L-1.3.Online analysis of different meat species,animal tissues and in-vitro cancer tissues using LAESI-TOFMS.LAESI-TOFMS has been used for rapid analysis of 5 meat species including pork,beef,mutton,chicken and duck.Discriminant model was built basing on statistical analysis,and characteristic ions of each kinds of meat were found.The result exhibited discrimination accuracy of 100%for all meat species.This study provides a new method for identification of meat species.In addition,porcine liver and kidney have been analyzed.The result showed good reproducibility of LAESI-MS for detection of tissue with the same type.Different type of tissue also can be distinguished effectively.The recognition of different tissue area was carried out,and the response time was less than 6 s.Two cases of in-vitro cancer tissue including liver cancer tissue and renal cancer tissue were analyzed.The result revealed that cancer tissue and health tissue showed significant differences in lipid species and content,and cancer tissue can be identified rapidly basing on mass spectral characteristics.This study indicates that LAESI-MS is a promising technique for intraoperative online analysis of cancer tissue and definition of resection boundary.