Paper aerosol has been developed as a fast sampling ionization method for direct analysis of natural biological and chemical samples using mass spectrometry (MS). through the analysis of a mixture of the methyl violet 2B and methylene blue. The mode of applying the aerosol solvent was found to HOXA11 have a significant impact on the separation. The results in this study led to a better understanding of the analyte elution on-paper separation as well as the ionization processes of the paper aerosol. This study also help to establish a guideline for optimizing the analytical overall performance of paper aerosol for direct analysis of target analytes using mass spectrometry. Keywords: Mass spectrometry paper NVP-BVU972 aerosol ionization on-paper separation therapeutic drug monitoring elution method hemoglobin blood analysis INTRODUCTION Paper is definitely a material that is produced by pressing collectively moist materials (normally composed of cellulose) and drying them into flexible sheets. Various types of papers have been made with appropriate modifications for chemical separation or permeability and several paper-based analytical techniques have been developed. For example in-paper size exclusion separation has been developed using filter papers [1 2 Paper chromatography has been well developed and applied since 1940s . Paper was used like a chromatographic substrate for quick separation and recognition of pigment mixtures based on the variations in the chemical affinity [3-5]. Considerable progresses in chemical analysis have been accomplished with on-paper separation methods through sophisticated derivatization of the paper substrates.[6-8] Combinations of the on-paper separation with additional analytical techniques NVP-BVU972 have also been wildly used among which the mass spectrometry (MS) is definitely a major method for the qualitative and quantitative analysis after the chemical separation [7 9 Mass spectrometry (MS) is definitely a powerful technique for chemical identification owing to its high sensitivity and specificity. To avoid severe matrix effects in the analysis of complex mixtures dedicated sample preparation and chromatographic separation are typically performed prior to the analysis having a mass spectrometer. Ambient ionization techniques  have been developed to allow fast analysis of uncooked samples by mass spectrometry with little or no sample preparation.[13 14 Recently paper aerosol (PS) was developed [15 16 as an ambient ionization method and applied for quantitative analysis of blood samples. With this method the analytes NVP-BVU972 inside a uncooked sample spot on a paper substrate are eluted by a small amount (about 10μL) of solvent to the tip of the substrate and then ionized for MS analysis with a high voltage applied on the wetted substrate. Paper serves as a good candidate material for consumable sample substrates and the dried blood places (DBSs) in writing have been used as a standard method for storing and transferring blood samples. One recent study showed by applying coagulant to new blood sample in writing substrate fast screening of therapeutic medicines in blood could be completed in 45s using PS-MS . Besides the software for analysis of dried blood places [18-20] PS-MS has also been shown for a direct and quick analysis of additional complex samples such as urine  cells  and food stuffs . Earlier studies have shown the properties of the paper substrates and the solvents for elution and ionization have significant impacts within the PS-MS analysis results such as the transmission duration transmission intensity and the ultimate level of sensitivity [21 23 In a study of the geometry of paper substrate spray tips of smaller angles generated higher spray currents but the highest NVP-BVU972 MS transmission intensity for the analyte was acquired with at 90o of the tip . The solvent applied for paper aerosol plays an important part in both analyte elution and the aerosol ionization processes. The amount of the solvent NVP-BVU972 utilized for PS affects the size of the sprayed droplets . By using solvents of relatively low boiling point and polarity for any silica-coated paper substrate limits of quantitation (LOQs) for restorative drugs in blood NVP-BVU972 were acquired at levels better than 1 ng/mL having a commercial triple quadruple and at 10-20 ng/mL having a home-built miniature ion capture mass spectrometer . The methods of applying the solvent for example inside a gradually wicking mode or a fast dumping mode were.