Investigations On Dielectric Barrier Discharge-optical Emission Spectrometry For The Simultaneous Determination Of Halogens By Vapor Generation

As a micro-plasma generation approach,dielectric barrier discharge(DBD)has many unique advantages,e.g.,small size,simple configuration,ease of operation,low temperature and low power consumption,which provide a feasiblility for the miniaturization of analytical instruments and has thus been paid wide attention in the field of spectrometric analysis.In the present work,DBD micro-plasma as a radiation source has been applied for the excitation of halogens and their simultaneous determination by optical emission spectrometry(OES)with oxidation vapor generation sampling approach.In the experiment,halide ions in an acidic sample solution are on-line reacted with an oxidant(KMnO4)to generate molecular halogen vapor by using a sequential injection system.The vapor species of halogens via gas-liquid separation are subsequently transferred into a DBD micro-plasma by a helium stream for the excitation and performing characteristic emission spectra,which is collected and recorded by a small charge-coupled device(CCD)spectrometer for the detection of halogens.Under certain experimental conditions,the characteristic emission of Cl at 837 nm,Br at 827 nm and I at 905 nm as the analytical lines are measured by the DBD-OES system for the simultaneous determination of Cl/Br and Br/I,respectively.Several factors governing the vapor generation efficiency and the DBD micro-plasma performance are investigated,including acidity of sample solution,concentration of KMnO4,input voltage and helium flow rate.A linear range of 0.03-10 mg L-1 is obtained for the simultaneous determination of chloride and bromide by the present system,along with detection limits of 0.017 mg L-1(C1-)and 0.011 mg L-1(Br-).The precisions of 1.7%(C1-)and 1.2%(Br-)are achieved at 3 mg L-1 chloride and bromide,respectively.The linear ranges of 0.03-10 mg L-1(Br-)and 0.30-10 mg L-1(I-)are obtained for the simultaneous determination of bromide and iodide by the present system,along with detection limits of 0.010 mg L-1(Br-)and 0.095 mg L-1(I-).The precisions of 1.4%(Br-)and 2.0%(I-)are achieved at 3 mg L-1 bromide and iodide,respectively.To demonstrate the reliability and practical usefulness,the present DBD-OES system is applied for the determination of chlorine,bromine and iodine contents in real samples,i.e.,GBW10023 laver,GBW13150 seawater,BW-HZ001 wakame and environmental seawater,giving rise to favorable results.