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

• Published in: Analytical chemistry (Washington) Vol. 90; no. 5; pp. 3036 - 3044
• Main Authors: Alavi, Sina, Khayamian, Taghi, Mostaghimi, Javad
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 06.03.2018
• Subjects: Analytical chemistry; Chemistry; Computational fluid dynamics; Computer simulation; Detection limits; Fluid flow; Heat transfer; Inductively coupled plasma; Magnetohydrodynamics; Mass spectrometry; Mass spectroscopy; Mathematical models; Plasma physics; Plasmas (physics); Power consumption; Reduction; Spectrochemical analysis; Spectroscopy; Temperature
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/acs.analchem.7b04356

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.