A New Aerosol Generation Technique for Elemental Mass Spectrometry
| Authors | |
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| Year of publication | 2010 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | A new aerosol generation technique for elemental mass spectrometry. For introduction of samples to elemental analyzers, such as ICP MS, three techniques are routinely used: nebulization of liquid samples, laser ablation of solid samples and, for certain elements, volatile species generation. We have introduced substrate-assisted laser desorption (SALD) for off-line analysis of liquid samples recently; the method is advantageous for submicroliter sample analysis and for off-line coupling of ICP MS to microcolumn separations, such as capillary electrophoresis. Here we present a novel technique of aerosol generation for off-line elemental analysis of liquid samples. Unlike SALD, it does not require expensive pulse lasers. Samples for preliminary analyses were prepared by pipetting submicroliter volumes of metal salt solutions on a suitable substrate. The samples were then desorbed in a commercial ablation cell equipped with a continuous-wave diode laser and transferred into a quadrupole ICP mass spectrometer with a collision cell. For desorption, 300 mW 808 nm or 150 mW 980 nm diode laser was employed. The tested substrates included paper, plastics, glass and aluminum. Various additives, such as near infrared dyes or common printer ink were added to samples to promote aerosol generation. To prove the concept of the new aerosol generation technique, a series of samples containing 12 pmol Co (200 nL 60 uM aqueous Co(NO3)2 solution) was deposited on paper with pre-printed circles. The printer ink promoted absorption of desorption laser light. Due to substrate pyrolysis and/or combustion induced by the laser beam, sample aerosol was generated and Co was determined with RSD 9%. The method was tested for analysis of Cr, Cu, Co, Fe, Ni, Sn and Zn; sub-picomolar detection limits were achieved. Influence of experimental parameters (substrates, additives, lasers) will be discussed. Analysis of an unknown sample using a prearranged calibration set on substrate will be demonstrated and benefits of the new technique (archiving, portability, sample throughput) will be discussed.A novel aerosol generation technique for economical elemental analysis of liquid samples using diode lasers-an alternative to nebulizers. |
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