T.Frentiu, M. Ponta, S.D. Anghel, A. Simon, A.-M Incze, E. Cordos, Investigation of medium power radiofrequency capacitively coupled plasmas and their application to atomic emission spectrometry for the determination of aluminium in water samples, Microchimica Acta, 147/1-2 (2004) 93-103

Title: Investigation of medium power radiofrequency capacitively coupled plasmas and their application to atomic emission spectrometry for the determination of aluminium in water samples

Abstract: A medium power radiofrequency capacitively coupled plasma (275 W, 27.12 MHz) with low argon consumption (0.5 L min⁻¹) was investigated to be used for the determination of aluminium in water samples pneumatically nebulised by atomic emission spectrometry. The plasma torch was operated in two geometric configurations, coaxial and coaxial-annular with single (SRTr.f.CCP) or double ring electrodes (DRTr.f.CCP), respectively. The optimum experimental parameters (observation height, Ar flow rate, distance between ring electrodes, matrix interference of Na⁺ and Ca²⁺ and anion nature) for Al 396.152 nm emission were established. Under optimum operating conditions of the DRTr.f.CCP torch (6 cm distance between annular electrodes), a detection limit of 70 ng mL⁻¹ aluminium was found. Both operating parameters and several figures of merit of the investigated plasmas were compared to those of microwave plasmas and inductively coupled plasma used in atomic emission spectrometry. The method was used to control the quality of drinking and industrial water. Samples were mineralised with 2 mL of 1+1 HNO₃ and 10 mL of 1+1 HCl. In the range of 0.15–3.5 mg L⁻¹ Al³⁺ the relative standard deviation varied between 3.7 and 8.6% (n=3). For two certified drinking water samples containing 0.206 and 0.218 mg L⁻¹ Al³⁺ the recovery (n=5) was 97.6±6.8% and 98.6±7.3%, respectively.

Key words: Plasma optical emission spectrometry; capacitively coupled plasma; aluminium determination; drinking water analysis

Author: A.M Incze