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Sen Han Juanjuan Feng Xiangping Ji Chunying Li Xiuqin Wang Yu Tian Min Sun 《Journal of separation science》2019,42(21):3363-3371
Nano‐molybdenum trioxide was prepared from nano‐molybdenum disulfide by simple firing in muffle furnace. Nano‐molybdenum trioxide was used as the extraction coating on the stainless steel wire. Four wires were filled in a polyetheretherketone tube to get an extraction tube. The tube was connected to the six‐port valve of a high performance liquid chromatograph, and the online analysis system was constructed. Extraction selectivity of the tube for different types of compounds, including polycyclic aromatic hydrocarbons, plasticizers, estrogens, anilines and neonicotinoids, was studied. Good enrichment ability for polycyclic aromatic hydrocarbons, but the extraction efficiency of others was not satisfactory. Using eight polycyclic aromatic hydrocarbons as the targets, an analytical method was established after optimizing main factors such as sampling volume, sampling rate, methanol content, and desorption time. The established method exhibited wide linear range to 0.016–20.00 μg/L and low limits of detection to 0.005 μg/L, and the enrichment factors can be up to 2443. The method was applied to the detection of trace polycyclic aromatic hydrocarbons in tap water and river water, and a good recovery was obtained. The tube showed good durability and chemical stability, and it still remained good extraction effect after more than 140 run. 相似文献
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采用在线富集/高效液相色谱(HPLC)与电感耦合等离子体质谱(ICP-MS)联用技术,建立了玩具中超痕量可迁移六价铬的测定方法。以10 mmol/L硝酸铵为流动相,样品在Agilent BIO WAX NP5阴离子交换柱(4.6 mm×50 mm,5μm)中富集,再通过阀切换,以75 mmol/L硝酸铵将六价铬洗脱至Dionex AG7阴离子柱(4.0 mm×50 mm,10μm)中分离,最后经ICP-MS进行分析。优化得到在线富集时间为4 min,进样量为900μL,富集流速为0.4 mL/min,洗脱流速为0.6 mL/min。结果显示,六价铬在2~20 ng/L范围内线性良好,检出限为1.93 ng/L,相对标准偏差(RSD)为3.9%。与直接进样相比,浓缩因子约为8.1倍,富集效率约为90%。对欧盟玩具安全指令2009/48/EC规定的3类玩具材料在5、10 ng/L的浓度水平下进行加标回收,回收率为93.4%~111%。 相似文献
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The present article describes a capillary zone electrophoresis method which relies on a multilayered water-alkali solvent stacking with online ionization to enhance detection of mannose, arabinose, and their oligosaccharides, which are used as the migration profile standards but are also the distinctive structural components of lipoarabinomannan. Lipoarabinomannan is detected in patients having tuberculosis. The capillary electrophoresis method with ionization of the whole saccharides without degradation in alkaline solution inside the capillary is based on the structural deprotonation of the molecules under ultrahigh pH conditions. The validation of the capillary electrophoresis parameters revealed that the 15-fold electrolyte–water-injection plug allowed detection of one-third lower concentrations than detected without online concentration. For the first time, the better detectability was seen especially for highly polymerized, but otherwise poorly ionized, arabinooctaose. The applicability of the method for detecting whole large biological saccharide complexes was confirmed by the glycolipid lipoarabinomannan. For the first time also, the migration of the indestructible lipoarabinomannan was detected together with oligosaccharides used representing the capping units, namely mannose, mannobiose, and mannotriose. The myo-inositol-phosphate-lipid unit was seen to migrate separately from the arabinomannan, since it was hydrolyzed from one lipoarabinomannan product under alkaline conditions in capillary electrophoresis. 相似文献
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A capillary electrophoresis-acid barrage stacking online enrichment method has been established to detect the four isoflavones which are Daidzein, Genistein, Formononetin, and Biochanin A. The proposed method was optimized using a single factor alternative method, and the optimal conditions obtained from the optimization were: the BGE was 25 mM borax and 2 mM β-cyclodextrin, the applied separation voltage was 20 kV, and the detection wavelength was 260 nm. The time ratio of the injection of sample and the injection of acid was 150 s:20 s, and the acid used was 250 mM acetic acid. The sample solvent used was 60% v/v acetonitrile. The established method had the enrichment factor of these four isoflavones at 24.5, 32.0, 29.2, and 33.7, respectively, LOD and LOQ are as low as nanograms per milliliter. Finally, the CE-acid barrage stacking method was successfully applied to the determination of four isoflavones in rat plasma and red clover extract, verifying the applicability and feasibility of the method. 相似文献
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结合大学化学的教学现状,针对学生的需求,深入思考在教学过程中设置习题课的重要性和相关问题。从教师素质、班级规模、教学方法、习题构建与讲解以及考试等不同角度提出有效提高习题课效率的策略。进一步探讨线上线下混合式习题课教学模式的可行性,并提供可参考的教学案例,以期促进大学化学专业课程的教与学。 相似文献
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为了准确测定黄精中稀土元素的含量,采用电感耦合等离子体质谱(ICP-MS)法同时测定黄精中15种稀土元素(La、Ce、Pr、Nd、Pm、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu)的含量,进而绘制稀土元素指纹图谱,以稀土元素含量的平均值构建黄精稀土元素标准指纹图谱,作为鉴定黄精中药材的参考依据。黄精样品采用微波消解法处理后,通过在线引入内标溶液,采用ICP-MS法测定15种稀土元素的含量,采用OriginPro 2021绘制稀土元素指纹图谱和进行主成分分析,采用SPSS 26.0进行聚类分析。15种稀土元素的线性关系、重复性、精密度良好,平均加标回收率在97.0%~103.3%,相对标准偏差小于等于1.74%。黄精中Ce、La、Nd含量相对较高,Ce含量为53.02~2004.58 μg/kg,位居第一。聚类分析和主成分分析结果表明,样品聚为2类,同一产地的样品能够较好地聚在一起。黄精药材中15种稀土元素的指纹图谱具有相似的分布形态,具有较强的特征性和一致性,相似度均大于0.950。该方法操作简单,准确可靠,能满足实验分析要求,可为黄精的质量控制和药理研究提供参考;建立的指纹图谱可用于黄精的鉴别。 相似文献