抑霉唑的毛细管电泳手性拆分及其在线富集

采用毛细管电泳法对抑霉唑进行手性拆分,研究了手性选择剂β-环糊精 (β-CD)、有机添加剂、NaH₂PO₄、NH₄H₂PO₄和分离电压对手性拆分的影响;同时,采用堆积法对抑霉唑进行在线富集,研究了进样压力和进样时间对在线富集的影响。结果表明:在分离电压为20 kV、β-CD浓度为5 mmol/L及缓冲体系为2.5% 异丙醇 + 75 mmol/L NaH₂PO₄ + 5 mmol/L NH₄H₂PO₄时,抑霉唑获得最佳分离度,分离度可达3.0;在分离电压为20 kV、β-CD浓度为5 mmol/L、缓冲体系为75 mmol/L NaH₂PO₄ + 5 mmol/L NH₄H₂PO₄ + 50 mmol/L H₃PO₄及进样条件为13.8 kPa × 99.9 s时获得最高富集倍数,富集倍数达91~92倍。     

Determination of ultratrace cadmium in food and environmental samples by ETAAS after vapor generation and in situ preconcentration

A method is described for the determination of ultratrace cadmium by coupling a continuous flow vapor generation system with in situ preconcentration technique and electrothermal atomic absorption spectrometry (ETAAS). A graphite tube coated with Ir as permanent chemical modifier was used for trapping cadmium vapor species. The effects of the flow rates of carrier gas and sample injection in vapor generation systems on the trapping measurement for cadmium were respectively investigated. Graphite tubes with different characteristic surfaces were comparatively studied for trapping cadmium vapor. The experimental results showed that the permanent chemical modifier of Ir is an alternative to the thermolabile modifier of Pd for simplifying the trapping measurement. The trapping efficiency of cadmium on the graphite tube coated with Ir was estimated. The trapping temperature and time were also investigated. A detection limit (3σ) of 0.005 μg·L⁻¹ was obtained for this proposed method. The relative standard deviation (RSD) was 1.4% for 0.5 μ·L⁻¹ of Cd (n = 11). This method can be applied to the determination of ultratrace cadmium in food and environmental samples with good agreement between the certified and found values.     

Separation of Ag(I) Ions from Lepidium draba L. Plant and Water and Standard Samples by Carrier Element-Free Coprecipitation Method Prior to their Flame Atomic Absorption Spectrometric Determination

In this work, silver iodide (Ag(I)) ions were separated via the carrier element-free coprecipitation (CEFC) method using an organic coprecipitating agent, 1,6-diamino-4-(4-chlornphenyl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile [DCODD] prior to its determination by ?ame atomic absorption spectrometry (FAAS). Analytical parameters including pH of aqueous solution, amount of DCODD, standing time, centrifugation rate and time, and sample volume were studied and optimized. Under the best experimental conditions, it was found that extraction can be performed from the sample volume of 500.0 for silver ion (preconcentration factor of 100.0). Linearity was maintained between 0.006 and 1.50 µg.mL^?1 for silver. Detection limit for silver based on 3Sb was 1.60 ng.mL^?1. The relative standard deviation of eight replicate measurements of 0.20 µg.mL^?1of silver was 2.10%. Finally, the developed method was successfully applied to extraction and determination of the silver ions in the Lepidium draba L plant, water and standard samples and satisfactory results were obtained.     

Preparation of Modified Magnetic Cobalt Nanoparticles as a New Magnetic Sorbent for the Preconcentration and Determination of Trace Amounts of Lead Ions in Environmental Water and Soil (Air-Dust) Samples

In this study, cobalt magnetic nanoparticles (MNPs) were synthesized and then modified by sodium dodecyl sulfate (SDS) and 2-(5-bromo-2-pyridylazo)-5-diethyl aminophenol ligand (5-Br-PADAP), through a chemical precipitation method. Characterization of the prepared MNP adsorbents was performed by Fourier transform infrared and transmission electron microscopy. Cobalt nanoparticles (NPs) surface modified with SDS and 5-Br-PADAP was evaluated as a nanoparticulate solid-phase extraction (SPE) absorbent for lead ions Pb(II) from water and standard samples, prior to its flame atomic absorption spectrometry determination. Effects of pH, amount of sorbent, desorption solvent, adsorption time, desorption time, and interfering ion concentration on extraction efficiency were investigated. Under optimal conditions, the calibration curve was linear in the range of 1.0–500 ng mL^?1of Pb(II) with R² = 0.998. Detection limit was 1.6 ng mL^?1 in the original solution (3S_b/m), and the relative standard deviation for replicate determination of 0.5 μg mL^?1 Pb(II) was ±2.7%.     

Determination of Water-Soluble and Acid-Soluble Zinc in Soils by Flame Atomic Absorption Spectrometry after Cloud Point Extraction

A cloud point extraction (CPE) procedure has been developed for the determination of water-soluble and acid-soluble zinc (Zn) in soils by flame atomic absorption spectrometry. Deionized water and 0.1 mol L^–1 hydrochloric acid (HCl) were selected as extracting agents. In the proposed approach, 2-(5-bromo-2-pyridylazo)-5-diethylam-inophenol (5-Br-PADAP) was used as a chelating agent, and polyethylene glycol octyl phenyl ether (OP) was selected as the surfactant. Some factors including the pH of analytical solution, concentrations of the chelating agent and surfactant, equilibration temperature and time, and salt effect, which would affect the extraction efficiency and subsequent determination of Zn, were studied and optimized. Under the optimized conditions, the calibration graph was linear in the range of 5.0?×?10^–3 to 0.5 μg mL^–1, and preconcentration of 20 mL sample solution gave an enhancement factor of 25. The detection limit was 4.93?×?10^–3 μg mL^–1. Recoveries in the range of 95.0–110% were obtained. Some metal ions including iron (Fe²⁺), cobalt (Co²⁺), and manganese (Mn²⁺) would interfere with the determination of Zn. The interference from these ions can be eliminated using thiourea (0.5% w/v) and triethanolamine (0.5% w/v) as masking agents. The proposed method was applied to the determination of water-soluble and acid-soluble Zn in soils, which were collected from the suburbs of Zhengzhou, and satisfactory results were obtained. To have more understanding of the soils, we determined the total content of Zn in soils. The results showed that the water-soluble and acid-soluble Zn contents in different soils are not correlated with the total content. For example, the total content of Zn for the soil from a farm in north loop was very low, but the percentage of water-soluble Zn was very high.     

Determination of Trace Amounts of Cadmium Ions in Water and Plant Samples Using Ligand-Less Solid Phase Extraction-Based Modified Co3O4 Nanoparticles

In this study, a new Co₃O₄ nanoparticles (NPs) coated with sodium dodecyl sulphate (SDS) is developed for preconcentration of trace amounts of cadmium ions (Cd ²⁺) as a prior step to its determination by flame atomic absorption spectrometry (FAAS). The effects of various parameters, including pH of sample solution, amount of sorbent, flow rates of solution and eluent, sample volume, type, and least amount of the eluent for elution of the Cd ²⁺ from Co₃O₄ NPs were studied and optimized. Experimental conditions for effective separation of trace levels of the Cd ²⁺were optimized with respect to different experimental parameters in Column method. Under the best experimental conditions, the calibration curve was linear in the range of 1.0–500.0 ng.mL^?1 of cadmium (Cd) with R² = 0.999. The detection limit was 0.4ng.mL^?1 in the original solution (3S_b/m) and the relative standard deviation for eight replicate determination of 0.1µg.mL^?1 Cd was ±2.1%. The method was validated by the analysis of a certified reference material with the results being in agreement with those quoted by manufactures. The developed method was successfully applied to the extraction and determination of Cd in water and food samples with satisfactory results.     

分子印迹技术在线富集测定玉米中嗪草酮残留

为了对玉米中的嗪草酮残留进行高效的分离、富集和测定,以嗪草酮为模板分子,采用原位聚合法制备了分子印迹聚合物,并将印迹聚合物作为固相萃取柱用于玉米样品的前处理过程,建立了在线富集液相色谱法测定玉米中嗪草酮残留的分析方法。研究结果表明,嗪草酮印迹聚合物具有良好的亲和性和特异选择性,在0.01~0.50 μg/mL质量浓度范围内有良好的线性关系(r=9991),最低检出浓度(S/N=3)为1.8×10-3 μg/mL,在0.01,0.05,0.10 mg/kg 3个浓度的添加水平下,方法的平均回收率在80.9%~94.5%之间,相对标准偏差低于5.98%。方法简化了样品前处理步骤,提高了检测灵敏度度,分析时间短,无基质干扰,精密度和准确度高,可应用于玉米中嗪草酮残留的分析检测。     

介孔SiO_2分离富集-火焰原子吸收法测定果汁中痕量铅

研究了介孔SiO_2分离富集-火焰原子吸收法测定果汁中痕量铅的新方法。探讨了溶液pH值、吸附温度、吸附时间、洗脱条件及共存离子对铅分离富集的影响。结果表明:在pH值为7.0、25℃吸附15 min条件下,Pb~(2+)可被介孔定量吸附,其静态饱和吸附容量为9.95 mg/g。吸附在介孔SiO_2上的可用0.05 mol/L EDTA完全洗脱。该方法线性范围0.2~10.0μg/m L,检出限为2.04 ng/m L,相对标准偏差(RSD)为3.4%(n=11,ρ=2.0μg/m L)。加标回收率为95.0%~97.5%。该方法可用于食品果汁样品中痕量铅的测定。