The Research Of New Hg/ As Vapor Generation Technique And Its Application In The Atomic Spectrometry

A review on the theory and application of vapor generation/electrochemical hydride generation(VG/EC-HG) sampling technique used in Atomic Spectrum(AS) was introduced in detail in this article. Determination of metal elements inenvironmental samples with atomic spectrum has been a very excellent analytical method. However, many analytical workers pay more attention to sample on-line, miniature apparatus and environment-friendly in actual works. In the article the experimental apparatus were set up ; the design theory was discussed ; the effect of detecting conditions were studied; the sample pretreatment techniques were investigated and analytical methods were developed.In the chapter one, the various vapor sampling techniques that applied to AS including cold vapor generation(CVG), hydride generation(HG) and volatilization generation were introduced firstly. Then, the atomic mechanism of chemical hydride generation(CHG)/EC-HG, possible interference and elimination, the design of electrolysis cell, the choice of electrode material and electrolyte, etc. were discussed. Finally, the improvement and application of CHG/EC-HG technique in AS were described.In the chapter two, a novel miniature CVG-AFS system was developed using amorphous Teflon AF-2400 tube as the gas-liquid separator and detection cell for the determination of Hg in tobacco, based on the Teflon AF-2400 tube's excellent gas transport behavior and high UV transparence. At the same time,the mechanization of design and gas permeation were discussed in detail. Under the optimal conditions, the detection limit was 0.02μg/L, and relative standard deviation ( RSD ) was 3.3% for eleven consecutive measurements of 0.50μg/L Hg standard solution. The novel system showed the advantages of micro-scale, low sample consumption and high sensitivity. The method had been successfully used in the determination of Hg in tobacco sample with recoveries of 97%–102%.In the chapter three, solid polymer electrolyte hydride generation technology (SPE-HG) for metal elements determination was first applied in AS analysis. A new SPE-HG cell, mainly composed of three components was laboratory manufactured and employed for detecting As in tobacco samples by coupling to AFS. A corrosion- resisting Ti mesh modified by Ir was chosen as anode material which could lengthen the cell's using life; high porous graphite felt with high hydrogen overvoltage was used as cathode, which enhanced the productivity of AsH3; Nafion 117 membrane as the ion exchange membrane and close contaction between electrodes with membrane reduced the power efficiency. Water as an alternative anolyte was first used in the SPE-HG cell. The entire arrangement was fastened with four clamps of C type at fourdifferent directions. So the new system has advangtages of low-cost, long-life, easy-assembly and environment friendly. It was successful to detect As in tobacco by coupling the new cell to Atomic Fluorescence Spectrum with high precision.