Papers by Author: Yan Li Zhang

Abstract: A new modified organo-bentonite using dithizone(D-O-bentonite) was used for preconcentration, separation and determination of silver(I) in natural water by flame atomic absorption spectrometry (FAAS). The experimental conditions for effective adsorption and elution of trace levels of silver (I) were optimized with respect to different experimental parameters. The influences of some common coexisting ions were also examined. The results show that the silver ion could be adsorbed on the D-O-bentonite. The adsorbed quantitively was affected by the pH value of medium and contact time. In the medium of pH 4-8, the contact time was 15 min, and capacity of the sorbent was 19.7 mg·g^-1. The silver(I) adsorbed on the sorbent could be completely eluated by using 1 mol·L^-1 HNO₃. The preconcentration factor is 100. The detection limit of the method for silver was 0.02 µg·L^-1. The method was applied to the pre-concentration/separation of silver in the environmental water with satisfactory results.

Abstract: A new system for determination of trace mercury based on separation and preconcentration with porous nano-barium-strontium titanate microspheres (PBSTM) prior to its determination by a hydride generation-atomic absorption spectrometry (HG-AAS) was propounded. The optimum experimental parameters for preconcentration of mercury, such as pH of the sample, contact time, sample volume, eluent and interfering ions, have been studied. The result showed that mercury could be quantitatively retained by PBSTM in the pH range of 4-8, the shaking time was 10 min, and the amount adsorbed was 12.2 mg·g^-1. The mercury adsorbed on the sorbent could be eluated completely with 2 mol·L^-1 HNO₃. The detection limit of this method for mercury was 6.3 ng·L^-1 with an enrichment factor of 60. The method has been applied for the determination of trace amounts of mercury in whole blood and urine with satisfactory results.

Abstract: A new method for the determination of traces of mercury in environmental and biological samples is described. The present methodology combines determined using a hydride generation-atomic absorption spectrometry (HG-AAS) with pre-concentration/separation of the analyte on dithizone-anchored organobentonite (D-O-bentonite). Optimal experimental conditions for the adsorption of the Hg, including pH, contact time, eluent concentration and volume and co-existing ions have been studied. The result showed that the mercury could be adsorbed on the D-O-bentonite. The adsorbed quantitively was affected by the pH value of medium and contact time. In the medium of pH 5.0, the adsorption time was 15 min, and capacity of adsorption was 23.2 mg·g^-1. The mercury adsorbed on the sorbent could be completely eluated by using 3 mol·L^-1 HCl. The adsorption agent has been applied to the pre-concentration/separation of mercury in surface water and human hair samples with satisfied results.