| In the new century, people have gradually realized that the sediment of the environmental persistent pollutants (mainly refers to the metal contaminants and antibiotic residues) in the soil, air, and water have damaged to the environment and human health. Metal pollutants can not easily be biodegradable; on the contrary they are able to biomagnification in the food chain, and enrich with the thousands of times. So that metal pollutants have a long-lasting harm in the water. At the same time, as the migration and transformation of pollutants, toxic metal ions enter into the living body through the food chain and accumulate, thus upset the equilibrium of the ecosystem and endanger human body health. Antibiotics are used in large amounts in clinical, aquaculture and agriculture. On the one hand, antibiotics transfer to the human body through the residues of the animals; On the other hand, birds also produce resistant strains which transmitted to humans. It is a serious threat to human health and existence. For the analysis of environmental samples, the sample pretreatment is an important aspect. Liquid-liquid extraction and solid phase extraction are the common environmental sample pretreatment methods. However, the methods are still undesirable for most analyses due to consumption of time and a large amount of volatile, toxic, pollution organic solvents. Additionally, these method can cause secondary pollution and high cost. Thus, the establishment of efficient, nontoxic, pollution-free and green separation/enrichment method is particularly important. Therefore, we established a green and non-toxic aqueous two-phase system (small molecular alcohol-salt aqueous two-phase system) to separate and concentrate the environmental persistent pollutants. Meanwhile, we also established a method which combined solvent sublation with spectrum method to separate/concentrate trace heavy metals in the environment. Once again, we created a new and green separation and concentration system which combined aqueous two-phase system and solvent sublation:Aqueous two-phase gas solvent sublation. And we used this system to analyse and detect the environmental persistent pollutants. The main subject of study from the following three aspects:(1) Separation and concentration the environmental persistent pollutants by aqueous two-phase extractiona. A new method for extraction of Cd(Ⅱ) by aqueous two-phase system with ethanol-(NH4)2SO4 was investigated. The main factors for Cd(Ⅱ) extraction and extraction mechanism were investigated with flame atomic absorption spectrometry (FAAS) FT-IR spectrum, respectively. The results showed that Cd(Ⅱ), I- and crystal violet could form a purple stable complex in the aqueous two-phase system of ethanol-(NH4)2SO4 while the pH value ranges from 5.0 to 6.0. Under the optimum conditions, the extraction yield of Cd(Ⅱ) reached 100.00%. The linear range was from 0 to 0.500μg·mL-1, and correlation coefficient of linear was 0.99926 with a RSD of 2.8%, and the detection limit of Cd(II) was 0.012μg·mL-1. Then the method was applied to the determination of Cd(Ⅱ) in actual water samples, and the satisfactory recovery (>95.00%) was obtained.b. An extraction indirect fluorophotometric method for determination of trace ampicillin was established in this paper. The method was based on the ampicillin degradation catalyzed by Zn (Ⅱ) ions with boiling water bath, the degradation product can be extracted with a n-butanol-salt-water two-phase system, and then the fluorescence intensity of the degration product was determined by spectrofluorimetry. The experimental conditions, such as the types of salts, the concentrations of K2CO3 and Zn (Ⅱ) ion, as well as heating temperature and time, were discussed and optimized. Linear range was from 5×10-6 to 9.0×10-5 mol·L-1, and the detection limit was 5.16×10-10 mol·L-1。The enrichment factor of this method can reach 26 times and a few of n-butanol is used. Under the optimum conditions, this method could be successfully applied for the analysis of Chang Jiang water, Well water and yu dai river water and the recoveries were in the range of 94.5%～100.2%. The method has been applied to the determination of trace ampicillin in water sample of the environment.(2) Separation and concentration the heavy metals by a method which combined solvent sublation with spectrum methoda. It is based on that diphenylcarbzide (DPC) can be oxidized by chromium (Ⅵ) to amaranthine diphenylcarbazone, which can associate with chromium (Ⅲ) to form a claret chromium (Ⅲ)-diphenylcar bazone complex in acid medium. This ternary complex has bad solubility and instability in water phase, whereas it can be dissolved easily in organic solvent of benzene with good stability and floated by N2 into benzene to form a real solution. Chromium (Ⅵ) content is determined in the solution by measuring the absorbance of organic phase. Then chromium (Ⅲ) is oxidized into chromium (Ⅵ) by ammonium persulfate and the total chromium can be determined by the same way, so that chromium (Ⅲ) content can be calculated by minus. The sensitivity of this method is improved about 10 times higher than that of water phase spectrophotometry through large dose enrichment. The apparent molar absorptivity is 4.2×105L·mol-1·cm-1, Beer’s law is obeyed in the range of 0～12μg/50 mL for Cr (VI). The relative standard deviation is 1.80%, the detection limit is 7.1×10-9mol/L, Because of the selectivity of the complexation and flotation, the method has highly good selectivity (most coexistence ions don’t interfere with the determination).b. Mn(Ⅱ) and 1,10-phenanthroline can form a stable coordinated cation [Mn(phen)3]2+, this cation can generate association complex Mn(phen)3(TIF)2 with basic dyes four iodine fluorescence (TIF). This association complex is unstable in water, but it is stable and easy dissolves in organic solvent. So a new method that ternary associated complex was flotated into the solution of benzene by N2 was established for the determination of Mn by photometry. The sensitivity of this method is high (8=9.6×105L·mol-1·cm-1), the relative standard deviation is 2.3% by measured six times of 4.0μg/200mL of Mn and the detection limit is 0.5μg·L-1. The method is suitable for the determination of Mn in natural water and wine.c. Cu(Ⅱ) and sodium diethyldithiocarbamate can form a coordination compound Cu(DDTC)2. The coordination compound is insoluble and unstable in water, while it is soluble and stable in organic solvent. So a new method that Cu(DDTC)2 was flotated into the solution of benzene by N2 was established for the determination of Cu by solvent flotation photometry. The sensitivity of this method is high (ε435=2.9×105L·mol-1·cm-1), the accuracy is satisfactory that the relative standard deviation is 2.0% by measured six times of 5μg/400mL of Cu(II), the limit of detection (LOD) is low that the LOD is 2.8×10-2μg·L-1when the flotation volume is 400 mL. The method is suitable for the determination of trace Cu in natural water.d. Pb2+ and I- can form a coordinated anion [PbI4]2-, this anion can generate ternary associated complex with basic dyes rhodamine B(RhB+). The ternary system is unstable in water, but stable in organic solvent. So a new method that Pb(Ⅱ)——I-——RhB+ system was flotated into the solution of benzene by N2 was established for the determination of Pb by solvent flotation. The sensitivity of this method is high (ε=2.2×105L·mol-1·cm-1), the selectivity is good and the accuracy is satisfactory that the relative standard deviation is 1.7% by measured ten times of 5μg of Pb. The electroplating wastewater before treatment was detected in semiconductor factory.(3) Separation and concentration the environmental persistent pollutants by aqueous two-phase gas solvent sublationa. Combining solvent sublation with aqueous two-phase extraction (ATPE), a new preconcentration/separation method was established:aqueous two-phase gas solvent sublation (ATGS). Then ATGS was applied to preconcentrate/separate Cd (Ⅱ) in the environment prior to flame atomic absorption spectrometric determination. The effects of analytical parameters including pH, proper condition of phase separation, volume of complex reagent and flotation time on the recoveries of heavy metals were investigated. The recovery of Cd (Ⅱ) was 100%. Cadmium was concentrated 10 times using this method, which is much better than aqueous two-phase extraction alone. For concentrations of Cd (Ⅱ) from 0.050 mg·L-1 to 5.000 mg·L-1, the linear equation was F= 2.8967C-0.1474 and the linear correlation coefficient (R2) was 0. 9996. The detection limit of Cd (Ⅱ) was 0.0113 mg·L-1. Averaging 15 determinations of 1 mg·L-1 Cd (Ⅱ) gave a relative standard deviation of 1.8%. The proposed method is shown to be promising for preconcentration/separation before the determination of trace and ultra-trace substances.b. Studied on separation/enrichment of erythromycin antibiotic by [Bmim]BF4-inorganic salt aqueous two-phase solvent sublation.Taking [Bmim]BF4 as sublation solvent, color reaction agent was 75% H2SO4, the sublation solvent was [Bmim]BF4-H2O(V[Bmim]BF4:VH2O=1:1), the salting-out agent was Na2CO3 with 0.32 g·mL-1, pH=11.5 for ROX, and (NH4)2SO4with 0.32 g·mL-1, pH= 11.5 for ACE, respectively. The sublation time was 50 min, gas flow rate was 15 mL·min-1. Under the optimum conditions, the sublation efficiency was 75%～85% for ROX with enrichment multiple 21.25 and 80%～90% for ACE with enrichment multiple 22.5, respectively. |
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