Characterization of a microwave microstrip helium plasma with gas-phase sample introduction for the optical emission spectrometric determination of bromine, chlorine, sulfur and carbon using a miniaturized optical fiber spectrometer

Continuous flow generation of Br2, Cl and H2S Coupled to a low-power 2.45 GHz microwave microstrip He plasma exiting from a capillary gas channel in a micro-fabricated sapphire wafer with microsttip lines has been used for the optical emission spectrometric determination of Br, Cl and S using a miniaturized optical fiber CCD spectrometer. Under optimized conditions, detection limits (3 sigma) of 330, 190 and 220 mu g 1(-1) Br, CI and S, respectively, under the use of the Br II 478.5 nm, Cl 1439.0 mn and S 1469.0 run lines were obtained and the calibration curves were found to be linear over 2 orders of magnitude. In addition, when introducing CO2 and using the rotational line of the CN molecular band at 3 85.7 run the detection limit for C was 4.6 mu g 1(-1). The procedure developed was found to be free from interferences from a number of metal of C02 cations and non-metal anions. Only the presence CO32- and CN- was found to cause severe spectral interferences as strong CN and C-2 molecular bands occurred as a result of an introduction of co-generated CO2 and HCN into the plasma. With the procedure described Br, CI and S could be determined at a concentration level of 10-30 mg 1(-1) with accuracy and precision better than 2%. (c) 2007 Elsevier B.V All rights reserved.