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

摘要

Continuous flow generation of Br2,Cl2 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 microstrip 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(3a)of 330,190 and 220 mu g l~(-1)for Br,Cl and S,respectively,under the use of the Br II 478.5 run,Cl I 439.0 nm and S I 469.0 nm 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 385.7 nm the detection limit for C was 4.6 mu g l~(-1).The procedure developed was found to be free from interferences from a number of metal cations and non-metal anions.Only the presence of CO_3~(2-)and CN~-was found to cause severe spectral interferences as strong CN and C2 molecular bands occurred as a result of an introduction of co-generated CO2 and HCN into the plasma.With the procedure described Br,Cl and S could be determined at a concentration level of 10-30 mg l~(-1)with accuracy and precision better than 2%.