Conical Torch: The Next-Generation Inductively Coupled Plasma Source for Spectrochemical Analysis

Abstract

A completely new ICP torch for optical/mass spectrometry is introduced with a conical geometry leading to significant reduction in gas and power consumption. As a new holistic methodology, the torch has been designed on the basis of fluid flow patterns, heat transfer, plasma physics, and analytical performance. Computer simulations, capable of accounting for magneto-hydrodynamic effects, have been used to optimize torch geometry. The result is a "conical" torch with up to 70% reduction in argon flow and more than 4 times power density compared with traditional "cylindrical" torches. Based on experimental measurements, these features lead to a stable plasma with 1000-1700K higher excitation/rotational temperature and a 5-fold increase in electron number density compared to common torches. Interferences from easily ionizable elements (e.g., Na) are also observed to be minimized due to 3 times higher robustness (Mg II/Mg I ratio). Eventually, analytical parameters including detection limits for multielement analysis indicate comparable/better performance of the new torch in comparison with conventional torches.

Analytical performance of the Conical torch in inductively coupled plasma optical emission spectroscopy operating methanol and 1-propanol solutions

“…2,16 However, most of the approaches are not easy to apply in routine analysis and entail more Recently, a new Conical ICP torch has been presented as an alternative to the conventional (cylindrical) Fassel design. 18,19,20,21 Because of its geometry, the new torch is able to produce a plasma with 4 times higher power density (leading to higher excitation/rotational temperature, higher electron density, and higher robustness) compared with that generated with the Fassel torch, while consuming 50 to 70% less argon and up to 800 W less power. 18,19,20 Despite operating at lower argon flow and r.f.…”

“…18,19,20,21 Because of its geometry, the new torch is able to produce a plasma with 4 times higher power density (leading to higher excitation/rotational temperature, higher electron density, and higher robustness) compared with that generated with the Fassel torch, while consuming 50 to 70% less argon and up to 800 W less power. 18,19,20 Despite operating at lower argon flow and r.f. plasma power, the Conical torch shows comparable figures-of-merit and lower Na-based matrix effects than those of the Fassel torch in both axially-and radially-viewed ICP-OES.…”

“…plasma power, the Conical torch shows comparable figures-of-merit and lower Na-based matrix effects than those of the Fassel torch in both axially-and radially-viewed ICP-OES. 18,21 Given its analytical features, the use of the Conical torch may be advantageous for the direct analysis of organic matrices without requiring complex experimental arrangements.…”

Development and Characterization of Ion Mobility Spectrometer

“…Atmospheric pressure plasma sources (APPS) are used for direct ionization of gas phase compounds or evaporated samples producing the ions to be transported to the analytical devices [2]. These analytical devices vary from optical emission spectrometer for liquid phase samples [3], ion mobility spectrometer for atmospheric gas samples [4], and time-of-flight systems for proteins and lipids [5].…”

“…The geometry of the ion source is also an important aspect which should be optimized for further stability of the produced plasma. An example is the optimized conical torch with the improved performance of ICP leading to a more stable operation of the plasma [3].…”