Electrohydrodynamic spray

Atmospheric pressure chemical ionization APCI is a method closely related to electrospray ionization. It uses ion-molecule reactions to produce ions from analyte molecules. The sample is electrohydrodynamically sprayed into the source (Figure 14.3). The evaporation of the solvent is often supported by a heated gas at temperatures between 80 and 400°C. Within the source, a plasma is created using a corona discharge needle that is placed close to the end of the metal capillary. In this plasma, proton transfer reactions occur, leading to the ionization of the analyte, mainly by the formation of [M+H]+ ions. Compared to ESI MS, APCI MS is very well suited for the analysis of less-polar components and can therefore... 

Hayati, L, A. Bailey, and T.R Tadros. Investigations into the mechanism of electrohydrodynamic spraying of liquids II. Mechanism of stable jet formation and electrical forces acting on a liquid cone. Journal... 

Cloupeau, M. and B. Prunet-Foch. Electrohydrodynamic spraying functioning modes A critical review... 

M. Cloupeau, B. Prunet-Foch Electrohydrodynamic spraying functioning modes a critical review, J. Aerosol Sci. 22, 1021-1036 (1994). 

Keywords Aerodynamic effects Charged droplets Cone jet Droplet evaporation Droplet deformation Electrohydrodynamic spray Electrospray Ion source Mass spectrometry Mass spectroscopy Rayleigh charge limit Spray modes Taylor cone... 

When the ions are at the fluid/air interface they form an electric double layer [3]. Here they apply an electrostatic force on the interface, which opposes the surface tension forces and deforms the drop. If a large enough electric field is applied, these ions can actually overcome the surface tension forces and break through the liquid/ air interface barrier [4]. This is essentially what happens in an electrospray (ES), also called electrohydrodynamic spray (EHD). This phenomenon is illustrated in Fig. 32.2. 

Prunet-Foch, Cloupeau, M., Bernard. (1994). Electrohydrodynamic spraying functioning modes. Journal of Aerosol Science, Vol. 25 (6), 1021-1036. Figures reprinted with permission from Elsevier. 

Sericin is a protein present in silkworm cocoons and is normally discarded in the degumming process. Sericin microparticles have been prepared by electrohydrodynamic spraying for use in drug delivery (61). 

Inkjet printing technology can be used with an electrohydrodynamic spraying technique (24). A conventional electrohydrodynamic inkjet device is based on DC voltage and requires two electrodes a nozzle electrode and an extractor electrode. However, this device suffers from drawbacks such as electrical breakdown. A more stable jetting technique uses the extractor electrode alone without the nozzle electrode and AC voltage. Thus, a continuous ejection of droplets can be obtained due to AC voltage. 

Hayati, I., A. I. Bailey, and Th. F. Tadros (1987). Investigations into the mechanisms of electrohydrodynamic spraying of liquids I. Effect of electric field and the environment on pendant drops and factors affecting the formation of stable jets and atomization. Journal of Colloid Interface Science 117(1) 205—221. 

O. Wilhehn, Electrohydrodynamic spraying -Transport, mass and heat transfer of charged droplets and their application to the deposition of thin functional films, Swiss Federal Institute of Technology, Zurich, (2004). 

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