The Development Of Solution Cathode Glow Discharge Atomic Emission Spectrometer For Determination Of Anions And Cations

With the development of modern industry, the pollution of the environment problem is becoming more and more serious. Many heavy metals and anions are released into soil, rivers and oceans which cause serious damage to the soil and water ecological environment. Therefore, fast, easy and efficient detection of metal ions is important for environmental monitoring.At present, solution cathode glow discharge atomic emission spectroscopy（SCGD-AES） technology is one of the fastest growing and most potential elements detection means. As a new element detection tool, it has attracted more and more attention in atomic spectrum analysis. Compared with traditional instruments（atomic absorption spectrometer, inductively coupled plasma atomic emission spectrometer / mass spectrometer）, it can be operated at atmospheric pressure, without acetylene or high purity argon as working gas, the less than 100 W operating power, sample injection without the use of nebulizers. However, due to its low excitation temperature of plasma, the detection sensitivity of some heavy metal was poor and can not meet the demand of practical application.In this paper, the atomizer of the SCGD-AES has been improved by changing its institutions which showed better stability and portability. The optimal working conditions utilized 0.1 mol/L HNO3 sample solutions and operated at a voltage of 1060 V with a flow rate of 2.0 mL/min.In order to improve the detection of lead, a flow injection-technique based on an on-line solid-phase extraction separation system coupled with solution-cathode glow discharge-atomic emission spectrometry（SCGD-AES） was developed for the determination of lead in aqueous samples. A newly synthesized adsorbent GO-SBA-15 was prepared and used as packing material for solid-phase extraction. In this system, lead was separated and preconcentrated on GO-SBA-15 and was detected by SCGD-AES. The dosage of SPE loading, preconcentration rate and condition of eluent has been optimized. And an enrichment factor of 15 was achieved under optimized experimental conditions. This method was applied in detection of lead in human hair（GBW09101b） and stream sediment（GBW07310） standard reference material. Measured values of SCGD-AES and the measured values ICP-MS（Inductively Coupled Plasma Mass Spectrometry） were consistent and agreed well with the reference values.On the basis of Schwartz et al, a replacement-ion chromatography technique coupled with solution-cathode glow discharge-atomic emission spectrometry（SCGD-AES） detection was developed for the determination of trace anions in aqueous samples. In this system, anions are stoichiometrically converted to Li salts when they pass through the replacement column, and are subsequently detected by SCGD-AES. By employing an offline regenerating resin replacement column, the continuous bleeding of the regenerant was reduced and the detection limits of anions were greatly improved. The optimal conditions operated at a voltage of 1060 V with an additional solution flow rate of 0.9 mL/min and utilized a 15 mM KOH eluent. The detection limits of several anions(F^-, Cl^-, Br^-, NO₂^-, NO₃^-, SO₄^2- and CH₃COO^-) were between 4 and 17 μg/L. The analytical methodology was successfully applied to real water sample analyses, and the results agreed well with the corresponding values obtained by ion chromatography.