Computer Aided Development Of Extractive Electrospray Ionization

Extractive electrospray ionization (EESI) is a new technology developedresently, which apply to analyze directly complex matrices sample using massspectrometry (MS) without any pretreatment and has been studied comprehensivelyover the years. EESI source consists of electrospray ionization (ESI) channel andsample channel, of which the spatial location parameters, relative to MS sample inlet,needs to be optimized to get the best detection signal. However, the homemade EESIsource, composed of stainless steel bar, cardan, three-way pipe, can not be operatedstably and precisely for spatial location parameters, that restricts development ofEESI technology.Firstly, in the paper, the principle and constitution of EESI source wereintroduced to illustrate theoretically the effect of spatial location parameters betweenEESI source and MS inlet to MS detecting signal intensity. And the existingequipments, features and outlook of EESI were presented to underline importance todevelop domestic instruments.Then, the general design scheme of an adjustable equipment for EESI was cameup with, of which the detailed structure, dimensions and materials were designedlately. The problem of angle changed leading to displacement was solved in theory.The design performance was listed in the end of the section.And next, with computer aided method,3D models for the adjustable system forEESI source were created, on basis of which kinematics analysis and simulation weremade proving feasibility of the design. Basing on computer vision technology, minihead holes of the main bodies were detected with photos. And a program using leastsquare method was made to evaluate diameter and diameter error, which was used tocompare two types of process, electrical discharge machining and welding mouldingpipe, to make mini head holes.Finally, an EESI-MS system was built, basing on which amino acid,chloramphenicol, reserpine etc were tested, existing EESI source the adjustable EESIsource were tested and compared, and the representative amino acids, valine, phenylalanine praline and so on, in blood samples obtained from patients with lungcancer, had been tested continuously for5days and the average RSD for each samplewas less than10%.The experimental results showed that the newly developed adjustable system forEESI source has been improved, particularly on the aspects such as stability, precisionand sensitivity.