Enhanced Paper Spray Mass Spectrometry And Application

Mass spectrometry(MS)analysis is a kind of method with high specificity and high sensitivity,which has been widely used in pharmaceutical analysis,life science,and environmental monitoring.For conventional MS analysis,the pretreatment for samples of complex matrix is time-consuming.Ambient MS ionization sources are characterized with minimal sample preparation for MS analysis.Ambient MS analysis is real-time,in-situ and on-line,which has been demonstrated as a rapidly growing field.Paper spray ionization(PSI)is a kind of ambient ionization source,in which paper spray mass spectrometry(PS-MS)can be performed on a piece of paper.The sample loaded on paper is extracted and transported to MS inlet by solvent with high voltage.PSI-MS has a promising potential for applications because of the characteristics of simple operation and low cost.With the development of PS-MS and the improvement of analysis requirements,the improvement of PS-MS is a hot topic of research.The spray solvent plays a significant role in PS-MS.The solvent is important to the performance of PS-MS,which not only plays a role in extraction and transportation of sample,but also has an effect on spray time and detection efficiency.Therefore,it is significant to have research on the solvents in PS-MS,but there are still some problems in research about solvent as follows:1.The solvent in paper-based analytical device(?PAD)flows slowly on the paper substrate for the method of ?PAD combined with PSI,and the flow rate of so lvent is required to be accelerated.2.The solvent in PS-MS evaporates easily,which results in short spray time and detection time.In addition,when the solvent carrying with analytes migrates to the paper tips for ionization,the diffusion is around the paper substrate,which impacts on the sensitivity of detection for target analyte.Based on the above problems,we have the research of improved PS-MS and application,mainly from the following two aspects.Firstly,we put forward a method to accelerate the flow rate of solvent on the paper substrate for ?PAD combined with PSI,including the design and manufacture of ?PAD with razor-crafted open channels and ?PAD with two-ply channels to accelerate the flow rate of solvent on paper substrate.We made comparative studies with conventional?PAD.For ?PAD with razor-crafted open channels,longitudinal micron-sized grooves were carved in the hydrophilic channel along the path of liquid flow,and the flow rate of solvent was increased by laminar flow effect.For ?PAD with two-ply channels,an additional layer of hydrophilic channel was stacked on top of the conventional ?PAD.The effective pore radius of the paper channel were increased to accelerate the flow rate of solvent.In MS analysis,the flow rates of solvent for ?PAD with razor-crafted open channels and ?PAD with two-ply channels were accelerated in comparison with conventional ?PAD.Secondly,we presented a facile approach as PSI with a Teflon tube.The device of PSI with a Teflon tube was simply made up of the rectangular strip with tip inserted into a Teflon tube,and only the front end and back end of the paper were exposed.The front of the paper was closed to the MS inlet and the end of the paper was held by a stainless clip applied with a voltage.PSI with a Teflon tube could extend the spray time three times longer than that in conventional PSI by reducing the evaporation of volatile solvent(methanol).The application of detection of slowly eluting compound(methylene blue)consumed less solvent by PSI with a Teflon tube and more solvent by conventional PSI,and the MS analysis results were consistent in PSI with a Teflon tube and conventional PSI.Moreover,improved signal stability and better analytical performance could be achieved via analysis of amitriptyline in blood and fetal bovine serum samples.In addition,PSI with a Teflon tube could control the flow direction of solvent on the paper substrate because of the unique configuration of paper and introduced teflon tube.PSI with a Teflon tube reduced the solvent diffusion around the paper substrate and improved the detection efficiency of analytes carried by solvent to the MS inlet.The improved signal intensity was obtained in the application of analysis of tioconazole in urine samples.