Accurate Mass Measurement And Online Determination For Enzymatic Reaction By Dual-spray Microfluidic Chip Coupled With Electrospray Ionization Mass Spectrometry

Microfluidic chip coupled with mass spectrometry(MS)gradually developed into an important determination platform,due to its high sensitivity,low sample consumption and good qualitative property etc.However,conventional single taperchip showed some limitation in their functions and poor versatility.Therefore,the interface technique of the microchip with tandem MS is urgent to improve and refine.In this work,a dual-spray emitter microchip based on polydimethylsiloxane(PDMS)was designed and carried out the following researches.1.In this part,a precise mass determination was achieved based on the dual-spray emitter microchip coupled with time of flight mass spectrometry(TOF-MS).By adding a certain internal standard(known mass)as the reference,the online real-time calrbration for the target mass-to-charge ratio was acconplished.Based on the proposed method,accurate mass determination for rhodamine B(RhB),reserpine,emamectin benzoate as well as superoxide dismutase enzyme(SOD)were achieved.Compared with conventional pulsed switching ionization,the proposed method owned simple structure,without any additional voltage control equipments.2.In this chapter,preceding method was explored to monitor online enzymatic reaction based on dual-emitter microchip coupled with mass spectrometry(chip-MS).It supported the hydrolysis of acetylcholine(ATCh)under the catalysis of acetylcholinesterase(AChE),which was triggered in the overlapping region of the dual electrospray.The relationship between the ionic strength of the product and the concentration of reactants was in linearity,and thus the enzymatic reaction was confirmed to be a second-order reaction.Compared with the conventional strategy by microreactors,the proposed method provided a fast analysis,and it could accomplish the online real-time characterization of the whole reactio.Therefore,a characterization for the transient intermediates in rapid chemical reactions would be achieved.3.In order to address the sensitivity decreasing due to the open instrumental configuration in the proposed chip-MS system,a closed system was constructed used 3D printing technology.The closed system in a certain extent enhanced the stability of the electrospray,and thus the sensitivity as well as the reproducibility of the analytical method was improved.