Electron Elimination Method Based on Single Electrode Dielectric Barrier Discharge Ion Source / 分析化学

ABSTRACT

Based on the electric field shielding and insulation technology, the single electrode dielectric barrier discharge ion source ( DBDI ) has the characteristics of uniform discharging, stability, and high ionization energy, and thus can be used to detect various samples with a large range of polarity. However, the ionization energy is too high to reduce the background signal noise, and thus affects the detection effectiveness to low polarity and low boiling point samples. To enhance the detection effectiveness to these samples, a method of eliminating electrons of single electrode DBDI by using external metal electrodes was developed in this study. Then, the single electrode DBDI was improved by an external needle electrode and an external metal net, respectively. The mechanism of those external metal electrodes was discussed, and the experimental studies were carried out. The results showed that the external metal net technology had an advantage in improving signal to noise ratio ( SNR ) , and the enhancement of SNR for the detection of isoprocarb, perfluorooctanoic acid and SudanⅢwas about 5-6 times. Based on the technology, a method for determination of Sudan Ⅲ in chili powder was developed. The recoveries, RSD and LOD were 83. 7%-94. 6% , 5. 6%-9. 0% and 23 mg/kg, respectively. The external metal electrode technique has broadened the detection range of single electrode DBDI to the field of low polarity, low boiling point and complex samples.