On-line Separation And Preconcentration Of Arsenic In A Sequential Injection System With Detection By Hydride Generation-atomic Fluorescence Spectrometry And Arsenic Speciation

The purpose of this thesis was to develop a new method for the determination and speciation of arsenic by using sequential injection coupled with on-line separation and preconcentration-hydride generation-atomic fluorescence spectrometry.Chapter 1 is a brief review on the recent advances of arsenic speciation and on-line separation and preconcentration methods by coupling with flow/sequential injection. Atomic fluorescence spectrometry is also introduced.Chapter 2 described a sequential injection system incorporating dual micro-columns coupled with on-line separation and preconcentration hydride generation atomic fluorescence spectrometry for the speciation of inorganic arsenic. Silica bonded C18 beads and 717 anionic exchange resin were employed as adsorbents. As(Ⅲ)-PDC and As(Ⅴ) are retained in an appropriate acidic medium. Thereafter, two micro-columns were eluted separately by HC1 and the eluates were determined by atomic fluorescence spectrometry. The enhancement factor of C18 micro-column for As(Ⅲ) was 7, the relative standard deviation at 1μg L-1 (n=11) level was sr=2.8%,the detection limit was 0.02μg L-1 and the linear range was 0.05-1.5μgL-1. The enhancement factor of 717 anionic exchange column for As(V) was 8.2, the relative standard deviation at 1μg L-1 (n=11) level was sr=2.9%,detection limit was 0.03μg L-1 and the the linear range was 0.1-1.5μg L-1.The procedure has been validated by analysing a certified reference material of riverine water (SLRS-4) and spiking recovery of a lake water sample was performed.Chapter 3 developed a new method for the determination of arsenic by hydride generation atomic fluorescence spectrometry, using wood cellulose as adsorbent. In the experiment, the complex of arsenic could be retained onto the wood cellulose packed micro-column, which realized the purpose of the preconcentration of arsenic. The adsorbed arsenic was eluted by HC1 and determined by atomic fluorescence spectrometry. The linear range of the method was 0.05-1.0μg L-1,the enhancement factor was 8.8, the detection limit was 0.02μg L-1.The determination result of the national standard material (GBW10010) was in agreement with the certified value and the spiking recovery of a seawater was performed.