Characterization of rapidly-prototyped, battery-operated, argon-hydrogen microplasma on a hybrid chip for elemental analysis of microsamples by portable optical emission spectrometry

• Microplasma emission spectra for Ag, Ba, Ca, Eu, Pd, Rb and Sr are reported.
• Absolute amount detection limits ranged between 45 pg and 180 pg.
• Relative unit detection limits ranged between 15 and 60 μg/L (using 3 μL).
• The effect of vaporization temperature on analyte signals is reported.
• Ca and Mg concentrations in (medicinal) thermal spring water were determined.

A rapidly-prototyped, battery-operated, atmospheric-pressure, self-igniting Ar-H2 microplasma was interfaced to a portable fiber-optic spectrometer. The microplasma-spectrometer combination was used to document the spectral lines emitted when μL of dilute solutions of single element standards of Ag, Ba, Ca, Eu, Pd, Rb and Sr were first dried and then vaporized into the microplasma. A small-size, electrothermal vaporization system was used for microsample introduction. Identification of the prominent spectral lines for these elements is reported. It was found that the most prominent spectral line for Ba, Ca and Sr was different than that emitted from an inductively coupled plasma (ICP). In general, prominent spectral lines with low excitation energy were dominating, thus resulting in spectra simpler than those emitted from an ICP. Detection limits were between 45 and 180 pg (expressed in absolute amounts). When expressed in relative concentration units, they ranged between 15 and 60 μg/L (obtained using 3 μL diluted standards). Calibration curves were linear (on the average) for 1.5 orders-of-magnitude. Average precision was 15%. Analytical capability and utility was demonstrated using the determination of Ca and Mg in (medicinal) thermal spring water.