Simulation and parametric study of a novel multi-spray emitter for ESI–MS applications
- 293 Downloads
In this work, we propose a novel carbon nanofiber (CNF) emitter for electrospray ionization (ESI)–mass spectrometry (MS) applications. The proposed emitter comprises an array of CNFs around the orifice of a microscale capillary. The electrospray ionization process is simulated using a CFD code based on Taylor–Melcher leaky-dielectric formulations for solving the electrohydrodynamics and volume-of-fluid (VOF) method for tracking the interface. The code is validated for a conventional multiple electrospray emitter and then applied to simulate the CNF emitter model. The modeling results show that under steady state condition, individual cone-jets are established around each of the CNFs resulting in an array of electrosprays. The approach being taken to fabricate the CNF emitter is briefly discussed. Effects of geometrical parameters including aspect ratio of CNFs, total number of CNFs and distribution pattern of the CNFs on the electrospray performance are studied. The influence of operating parameters such as flow rate, potential difference and physical properties of the solvent on the electrospray behavior is thoroughly investigated. The spray current, ‘onset’ potential and jet diameter are correlated with total number and distribution of CNFs and physical properties of the liquid. The correlation results are compared with the available results in the literature. Higher spray current and lower jet diameter indicate that the device can perform equivalent to nanospray emitters while using a micro-scale orifice. This allows higher sample throughput and eliminates potential clogging problem inherent in nano-capillaries.
KeywordsCarbon nanofiber Electrospray ionization–mass spectrometry Taylor–Melcher leaky-dielectric formulations Electrohydrodynamics Volume of fluid
Supported in part by a grant from the University of South Carolina Research and Productive Scholarship Fund, NIH grant CA86285 and the NHLBI proteomics Initiative via contract N01-HV-28181 (D.R.K.).
- Amirkhani, A, Wetterhall M, Nilsson S, Danielsson R, Bergquist, J (2004) Comparison between different seathless electrospray emitter configurations regarding the performance of nanoscale liquid chromatography-time-of-flight mass spectrometric analysis. J Chromatogr A 1033:257–266CrossRefGoogle Scholar
- Bocanegra R, Barrero A, Loscertales IG, Marquez M (2003) Multiplexing electrosprays emitted from an array of holes. In: 56th annual meeting of the division of fluid dynamics, Bull Am Phys Soc 48Google Scholar
- Castellanos A (1998) Basic concepts and equations in electrohydrodynamics. In: Electrohydrodynamics, Springer, Berlin Heidelberg New YorkGoogle Scholar
- Chhowalla M, Teo KBK, Ducati C, Rupesinghe NL, Amaratunga GAJ, Ferrari AC, Roy D, Robertson, J, and Milne WIJ (2001) Growth process conditions of vertically aligned carbon nanofibers using plasma enhanced chemical vapor deposition. Appl Phys Lett 90:5308Google Scholar
- De la Mora FJ, Loscertales IG (1994) The current emitted by highly conducting Taylor cones. J Fluid Mech 260: 155–184Google Scholar
- J Liu, KW Ro, R Nayak, DR Knapp (2006) Monolithic column plastic microfluidic device for peptide analysis using electrospray from a channel opening on the edge of the device. Int J Mass Spectrom (in press)Google Scholar
- Kaiser S, Kyritsis DC, Dobrowolski P, Long MB, Gomez A (2003) The electrospray and combustion at the mesoscale. J Mass Spectrom 51(1):42–49Google Scholar
- Melcher J R (1981) Continuum electromechanics. MIT Press, CambridgeGoogle Scholar
- Schultz GA, Corso TN (2000) Proceedings of the 47th ASMS Conference on mass spectrometry and allied topics, Long BeachGoogle Scholar
- Wang XQ, Desai A, Tai YC, Licklider L, Lee TD (1999) Polymer based electrospray chips for mass spectrometry. In: Proceedings of the IEEE micro electro mechanical systems (MEMS), Orlando, pp 523–528Google Scholar