Performance Improvement Of Paper Spray Ionization Source And Its Applications

Paper spray ionization is a novel ambient source.This technique not only possesses the general characteristics of ambient ionization source,but also has the features of convenience,low-cost and high efficiency.However,the surface of paper substrate is composed of cellulosic fibers and contains a plenty of free hydroxyl groups.When analyzed with paper spray,target compounds are difficult to be eluted off in a short time,due to the strong hydrogen bond and van de Waals interactions between paper substrates and analytes.In order to weaken the interactions,improve the analysis sensitivity and expand the application of paper spray ionization,some efforts have been made in our experiment as below:?1?Metal-organic frameworks were selected and used as the coating materials to modify filter paper through a facile vacuum filtration method,by using starch as the adhesive agent.Meanwhile,the impact of different types of binder and the concentration of coating solution have been systematically investigated.The highest sensitivity analysis of verapamil was got when we used the paper coated with 0.6 g UiO-66?Zr?and 0.1 g corn starch.The acetonitrile was best spray solvent on the analytical sensitivity for verapamil using UiO-66?Zr?coated paper as the substrate for paper spray.Then the obtained MOFs coated paper acted as the substrate for paper spray to analyze therapeutic drugs in dried blood samples.Compared to uncoated filter paper,the analytical sensitivity of verapamil as a typical therapeutic drug,by using the as-prepared paper improved 13.1 fold.The repeatability?RSD=1.4%?and stability?RSD=3.1%?of the as-prepared UiO-66?Zr?coated paper substrate have been evaluated for paper spray mass spectrometry and were good enough.The analysis performance was examined using verapamil in dried blood spot samples.?2?The adsorption and desorption behaviors of MOFs[e.g.,MIL-53?Al?,ZIF-8 and UiO-66?Zr?]was systematically investigated by using paper spray mass spectrometry.Herein we explore the capability of various MOFs coated paper substrates for paper spray,in which the as-prepared UiO-66?Zr?coated paper demonstrated the highest sensitivity in the analysis of therapeutic drugs in dried blood spots.Compared to uncoated filter paper,the estimated lower limit of quantitation?LLOQ?values of the examined drugs with UiO-66?Zr?coated paper have improvements of 8.5-46.6 fold,and the values were in the range of 0.04-0.65 ng mL^-1.Based on the high sensitivity of UiO-66?Zr?coated paper in drug quantitative analysis,the developed paper has also been successfully applied for the analysis of five anti-psychotic drugs in human blood samples.?3?The adsorption and desorption behaviors of a typical therapeutic drug verapamil over various Zr-based MOFs in acetonitrile solution have also been systematically investigated by using paper spray mass spectrometry due to the UiO-66?Zr?coated paper exhibited the optimal performance in high sensitivity analysis of target drugs.we proved that the adsorption process of verapamil on the Zr-based materials fits well with the pseudo-second-order kinetic model.In contrast to other materials,UiO-66?Zr?-2COOH demonstrated a superior adsorption performance to verapamil due to their strong acid-base and hydrogen-bond interactions.To further get a better understanding on the interactions between drugs and Zr-based materials coated papers,the elution behaviors of target drug verapamil were explored from the Zr-based materials coated papers.Finally these coated papers have been used for the analysis of various drugs and proteins in the process of paper spray mass spectrometry.In summary,the present study of using MOFs coated papers not only improved the sensitivity of paper spray mass spectrometry,but also successfully applied for the analysis of five anyi-psychotic drugs.This study provides guidance for the application of metal-organic frameworks in clinical medicine.Meanwhile,We systematically investigated the adsorption and desorption behaviors of MOFs by using paper spray mass spectrometry,which provided a new measure for the study and application of new materials.