The DESI technique has several outstanding advantages over traditional techniques, including ambient sampling, high analysis speed and direct sample analysis with little need for sample preparation/preseparation. In the DESI technique, a pneumatically assisted electrospray jet is directed toward the sample surface to facilitate desorption/ionization. developed a new ambient surface sampling/ionization technique for mass spectrometry, termed desorption electrospray ionization (DESI) 17. Moreover, a known behavior about ELCAD is that the elemental emission intensity strongly depends on the pH of the solution, which restricted their applications 11, 16. However, most of the ELCAD are operated with flowing solution as one electrode, which necessitates the use of a sampling pump in the system 13. These liquid discharge devices offer advantages of small size, elimination the use of a nebulizer, low sample/power consumption and cost effectiveness. 11, 12, 13, 14 and liquid-film dielectric barrier discharge (LFDBD) developed by Zhu et al. In recent years, electrolyte-cathode discharge (ELCAD) has proven to be successful for solution analysis such as solution-cathode glow discharge (SCGD) developed by Hieftje et al. However, these technologies still have some shortcomings, such as expensive equipment required in nebulizer with the increased risk of clogging 8, 9 and serious memory effects on ETV 10. Later technologies such as micro-nebulizers and electrothermal vaporization (ETV) providing higher sample introduction efficiency with reduced sample consumption have indeed attracted some interests 5, 6, 7.

Conventional pneumatic nebulization as the most common sample introduction device suffers from low nebulization efficiency (<5%), high sample uptake rates (1вЂ“2вЂ‰mL min -1) and serious matrix interferences, which is problematic when sample volumes are small or sample with complex matrices 3, 4. The development and improvement of sample introduction systems have been one of the main challenges for scientists working in this field 2. In plasma based atomic spectrometry, the sample introduction has long been considered as the AchillesвЂ™ heel 1. The proposed MAPAES provides a new way for atomic spectrometry which offers advantages of fast analysis speed, little sample consumption, less sample pretreatment, small size and cost-effective. The detection limits were down to pg level with linear correlation coefficients better than 0.99. Qualitative and quantitative determinations of metal ions were achieved by atomic emission measurements for elements Ba, Cu, Eu, In, Mn, Ni, Rh and Y. The FP matrix served as the partial energy producer and also the sample substrate to adsorb sample solution. The matrix-assisted plasma atomization excitation phenomenon was observed for multiple elements. The FP absorbs energy from the plasma source and releases combustion heating to the analytes originally present on its surface, thus to promote the atomization and excitation process. MAPAES was carried out by direct interaction of the plasma tail plume with the matrix surface. An innovative technology has been developed involving a simple and sensitive optical spectrometric method termed matrix-assisted plasma atomization emission spectrometry (MAPAES) for surface sampling elemental analysis using a piece of filter paper (FP) for sample introduction.

Elcad plasma spectra