Improvement Of Paper Spray Mass Spectrometry And Its Application In Analysis Of Complex Samples

Accurate measurement of trace compounds in complex samples is of great importance in clinical diagnosis,life science and other fields.Paper spray ionization mass spectrometry is often used for the detection and analysis of analytes in samples because of its simplicity and economy.However,it suffers from matrix effect when dealing with complex samples,thereby reducing the sensitivity of the method,which limits the application of paper spray ionization mass spectrometry in these fields.Hence,it is of great importance to reduce the matrix effect generated by paper spray ionization mass spectrometry in the detection of complex samples.To make the paper spray ionization mass spectrometry more suitable for the detection of analytes in complex samples,we propose two methods to improve and develop it.One is to introduce paper-based analytical devices into paper spray,the advantages of paper-based analytical device in sample pretreatment can reduce the matrix effect;the second is to combine protein precipitation and paper spray with a tube,which was developed from the paper spray,to reduce matrix effect produced by blood samples.In the first part,we develop a new paper-based analytical device.Superimposing the hydrophilic channels of the multi-layer paper chip,and then eluting the analytes using the elution solvent.Due to the different solubility of different analytes in the elution solvent,high-efficiency chromatographic separation of complex samples can be achieved.This method separate two different dyes successfully,and it can separate analytes and matrix in complex samples.In addition,on the basis of paper spray,we have proposed graphite conductive paper spray.With the method of graphite conduction,it can reduce the effect of the hydrophobic barrier in paper-based analytical device,making it more convenient to combine paper-based analytical devices and paper spray.Compared with paper spray,graphite conductive paper spray also enhances the signal intensity of the analytes.In the second part,we combine protein precipitation and paper spray with a tube.A low-cost Teflon tube is used as a platform to precipitate the protein in blood.The analytes are extracted to organic solvent and the precipitated protein can be adsorbed by the chromatography paper inserted.Hence,the Teflon tube after precipitating can be directly subjected to paper spray ionization with a tube mass spectrometry,achieving one-step analysis of blood.High sensitivity and satisfactory stability are achieved when analyzing pharmaceuticals,acids and endogenic metabolites in blood.The absolute signal intensity of characteristic fragment ions of the tested analytes is 8-20 times higher than those obtained from paper spray with a tube.Detection limits and quantitative performance are evaluated for three drugs:carbamazepine,metformin and tioconazole.And the limits of detection and limits of quantitation are improved 9-14 and 8-12 folds,respectively.The experimental results show that protein precipitation coupled to paper spray with a tube mass spectrometry is sensitive,stable,convenient and economic for direct analysis of blood.