| Chinese herbal medicine is a unique drug that used to preventation and treatment of diseases, also is the important symbol that different from other medicine. Chinese herbal medicine is derived from heavy metal pollution in the environment pollution and in the acquisition and processing of transportation. Because of the heavy metals can not be biodegradable in environmental media, and can be riched through the food chain in the organism, eventually accumulate in the body and endanger human health, such as lead (Pb) have caused damage the nervous system, digestive system and hematopoietic function of bone, chromium (IV) would damage the skin and respiratory system, also will lead to renal failure and even cancer. Therefore, it was quite essential to build some accurate and convenient methods for the determination of heavy metals in medicinal herb samples. In this paper, analysis methods of two heavy metal ions including lead (Pb) and chromium (Cr) have been studied. The main contents are as follows:Part 1 Cloud-point extraction (CPE) of lead and chromium in Chinese herbal medicine samples prior to reacting with synthesized Schiff base by flame atomic absorption spectrometryChapter 1 Vortex-assisted cloud-point extraction (CPE) of lead and chromium in Chinese herbal medicine samples prior to reacting with synthesized Schiff base by flame atomic absorption spectrometryA new Schiff base was synthesized between O-phenylenediamine and salicylaldehyde and used as the chelating agent in this study. Non ionic surfactant AEO-9 as the cloud point extraction agent was proposed for the extraction and preconcentration of lead (Pb) and chromium (Cr) in Chinese herbal medicine samples prior to flame atomic absorption spectrometry determination. The optimum conditions of the proposed method were pH 7.0,10 μg/mL Schiff base, 100μL AEO-9,10 min equilibration time at 33℃ and 5 min centrifugation time at 3000 rpm. Under the optimized conditions, the calibration curves were linear in the range of 10-500 μg/L for Pb and Cr. The limits of detection (LOD) were 6.7μg/L and 3.2μg/L for Pb and Cr, respectively. The relative standard deviations (RSD, n=11) were 2.5-3.8%. Recoveries of Pb and Cr spiked into water samples were in the range of 90-116%, the enrichment factors of the analytes were 24 and 20 for Pb and Cr, respectively.Chapter 2 Supramolecular solvent-based extraction coupled with vortex-mixing for determination of palladium and silver in water samples prior to reacting with synthesized Schiff base by flame atomic absorption spectrometryA simple and practical extraction method of supramolecular solvents (SUPRAS) was developed for separation and enrichment of trace amounts of palladium (Pd) and silver (Ag) in water samples prior to flame atomic absorption spectrometry (FAAS) analysis. The SUPRAS selected was made up of an aqueous solution containing tetrahydrofuran and nonanoic acid. Pd and Ag reacted with diethyldithiocarbamate to form hydrophobic chelates, which were extracted into the vesicles of SUPRAS. Different parameters such as the concentration of chelating agent, sample pH, supramolecular solvent and the effect of foreign ions were studied. Under the optimal conditions, the linear ranges of Pd and Ag were from 10 to 1000 μg/L. The relative recoveries of Pd and Ag in tap and river water samples at the spiking level of 10 ug/mL ranged from 90.8 to 116%. The relative standard deviations were 3.6-4.0%(n=9), the limits of detection were 2.8 and 1.9 μg/L and the enrichment factors were 36 and 18 for Pd and Ag, respectively. The quantification limits were 3.2 and 2.4 μg/L. The method was successfully applied to the determination of Pd and Ag in water samples.Part 2 Suspension dispersive solid phase extraction for preconcentration and determination of lead, copper, and nickel in Chinese herbal medicine samples by flame atomic absorption spectrometryA novel extraction technique termed suspension dispersive solid phase extraction (SDSPE) is developed for selective separation and preconcentration of lead (Pb), nickel (Ni) and copper (Cu) in environmental water samples. The method is based on the reaction of zinc sulfate (ZnSO4) and sodium hydroxide (NaOH) and zinc hydroxide formed. The suspension state results from the dispersion of the fine particles of the sorbent in the bulk aqueous sample. The complexes of metal ions in the bulk aqueous sample with 1-(2-pyridylazo)-2-naphthol (PAN) are loaded on sorbents. After extraction, phase separation is performed by centrifugation and the enriched analyte in the sedimented phase is eluted by methanol and determined by flame atomic absorption spectrometry (FAAS). Some key parameters for SDSPE, such as the type and mass of sorbent, type and volume of eluent, concentration of the chelating agent, and equilibration time and sample volume are investigated and optimized. Under the optimal conditions, the enrichment factor (EF) of 20 is achieved with a sample volume of 40mL. The detection limit of this method for Pb, Ni, and Cu are 2.4,1.7 and 1.5μg L-1, and the relative standard deviation (RSD) are 4.3%, 2.7%and 1.6%at 10 μg L-1 concentration level of Pb, Ni and Cu, respectively. The method is successfully applied for these metals content evaluation in environmental water samples with satisfactory results.Part 3 Synthetic of colloidal silver solution combines Fe3O4 magnetic nanomaterials for preconcentration and determination of lead and chromium in Chinese herbal medicine samples by flame atomic absorption spectrometryThe method is based on the colloidal silver solution and the metal ions to form aggregates, Fe3O4 magnetic nanomaterials as adsorbents, hydrochloric acid solution as eluent for preconcentration and determination of lead and chromium in Chinese herbal medicine. The optimum conditions of the proposed method were pH7.0,2mLAgNPs,0.3g Fe3O4 magnetic nanomaterials,2mLHCl(2mol/L), vortex time for 5min,10 min centrifugation time at 3000 rpm. Under the optimized conditions, the calibration curves were linear in the range of 10-500μg/L for Pb and Cr. The limits of detection (LOD) were 0.13μg/L and 0.18μg/L for Pb and Cr, respectively. The relative standard deviations (RSD, n=11) were 2.3-3.6%. Recoveries of Pb and Cr spiked into water samples were in the range of 93-106%. The method is based on the colloidal silver solution and metal ions to form aggregates, with FesO4 magnetic nanomaterials to form double adsorption enrichment, and collecting the product was eluted by eluent, the flame atomic absorption instrument detection, it does not require the use of organic solvent and the green environmental protection, with high sensitivity and lower detection limit. |
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