A Preliminary Study On Screening Method For Derivatization Reagents In Electrospray Ionization Tandem Mass Spectrometry

Derivatization is a common techinique in the field of chemistry and biology that changes the properties of compounds by converting them into derivatives with similar structures to those of derivatization reagents,in order to improve the detection sensitivity.Up to date,derivatization has been widely employed for electrospray ionization tandem mass spectrometry?ESI-MS/MS?.However,for chemical derivatization-assisted ESI-MS/MS method,we often face with the following problems:?1?how to select reasonable derivatization reagents from great varieties of derivatization reagents??2?how to improve the ionization efficiency of analytes in MS detection??3?collision-induced dissociation progress of a compound is often very complex,how to change the collision-induced dissociation behavior of the compound by different derivatization reagents??4?what is the relationship between the ionization efficiency and collision-induced dissociation of derivatives and their sensitivity during ESI-MS/MS analysis?To tackle with these problems,it is still imperative to systematically study the ionization efficiency of analytes in electrospray ionization source and the mechanism and rules of collision-induced dissociation.This thesis mainly focused on theoretical calculation assisted screening methods for derivatization reagents during ESI-MS/MS analysis,including the following aspects:1.It has been reviewed that the ionization efficiency of compounds,collision-induced dissociation mechanism,and their relationship with the compound detection sensitivity during ESI-MS/MS analysis,also the derivatization techniques for ESI-MS/MS.2.By summarizing the collision-induced dissociation rule of thiourea,N,N-dimethylaminobenzene isothiocyanate was synthesized for derivatizating amino acids.The reagent,4-isothiocyanate-N,N-bis?methyl-[²H₂]?aniline was also synthesized,and its derivatives of amino acids were surved as internal standards to replace isotope labelled amino acids as internal standards.In total 12 amino acids associated with inherited metabolic diseases in dry blood spots could be simultaneously quantified with the established method.3.A simple screening procedure for derivatization reagents was established with the aid of theoretical calculations from their physico-chemical properties.Specifically,N-?9-acridine?-2-bromoacetamide?AYBA?for derivatizating carboxyl-containing or mercapto-containing compounds was synthesized based on this reagent screening method.With this reagent,we successfully established analytical methods for the spatio-temporal profiling of three acid phytohormones from single rice seed during seed germination,and quantification of 6 low-molecular-weight thiols from a single human cervical cancer cell.4.A quantitative structure-activity relationship?QSAR?model was established between the physicochemical properties of derivatization reagents and the detection sensitivity of their derivatives.From the established model,the most important physicochemical parameters were found that have the greatest influence on the sensitivity of derivatives during ESI-MS/MS analysis,and a preliminary quantitative screening method for derivatization reagents was established.