改良QuEChERS-气相色谱-串联质谱法同时测定土壤中17种邻苯二甲酸酯

建立了改良的QuEChERS法,结合气相色谱-串联质谱(GC-MS/MS)检测土壤中17种邻苯二甲酸酯的分析方法.样品用乙腈水溶液提取,NaCl盐析分层,上清液采用磁性氧化石墨烯(Fe3O4-GO)、N-丙基乙二胺(PSA)和无水MgSO4吸附剂分散固相萃取净化,质谱以多反应监测(MRM)模式测定,外标法定量.结果 表...     

毛细管区带电泳法快速测定阿莫西林克拉维酸钾片中阿莫西林和克拉维酸钾

阿莫西林克拉维酸钾片是阿莫西林和克拉维酸钾组成的复方制剂。阿莫西林为广谱青霉素类抗生素,克拉维酸钾本身只有微弱的抗菌活性,但具有强大的广谱β-内酰胺酶抑制作用,可保护阿莫西林免遭β-内酰胺酶水解。临床用于敏感菌引起的各种感染。其含量一般采用高效液相色谱（HPLC）法,本文采用高效毛细管电泳（HPMC）法快速测定阿莫西林克拉维酸钾片中阿莫西林和克拉维酸钾含量。     

ICP-AES法测定淀粉中的铅、汞、镉、砷

建立了ICP-AES法测定淀粉中铅、汞、镉、砷的方法。用HNO3、HClO4处理样品,然后用ICP-AES法进行测定。加标回收率为98．2％～104．3％,测定结果的相对标准偏差均小于5％(n=5)。     

超高效液相色谱-串联质谱法同时测定豆芽中氟喹诺酮类和硝基咪唑类抗生素的残留量

取5 g豆芽样品,加入100μg·L^-1混合内标溶液40μL和含1%(体积分数,下同)乙酸的乙腈溶液10 mL,振荡3 min,超声20 min,离心3 min。重复提取一次,合并上清液,用含1%乙酸的乙腈溶液稀释至25 mL。分取10.00 mL,置于装有QuEChERS吸附剂[100 mg N-丙基乙二胺(PSA)、100 mg C₁₈、800 mg无水硫酸镁]的离心管中,离心3 min,静置5 min。分取5.00 mL上清液于40℃氮吹至近干,加入1.00 mL含0.1%(体积分数,下同)甲酸的30%(体积分数)乙腈溶液,复溶后过0.22μm滤膜,滤液进入超高效液相色谱-三重四极杆质谱仪分析。12种抗生素在ACQUITY UPLC HSS T₃色谱柱(100 mm×2.1 mm, 1.8μm)上用不同体积比的含2 mmol·L^-1甲酸铵的0.1%甲酸溶液和含0.1%甲酸的乙腈溶液的混合液为流动相进行梯度洗脱分离,以电喷雾离子源正离子(ESI⁺)模式电离,以多反应监测(M...     

a,a,a,b-ZnT(o-BocThr)APP对咪唑衍生物和氨基酸酯的分子识别研究

Molecular Recognition of α,α,α,β-ZnT（o-BocThr）APP （1） toward a series of imidazole derivatives and amino acid esters was investigated. Association constants were determined in chloroform by means of UV-Vis titration method. The association constants of 1 with imidazole derivatives are larger than those of 1 with amino acid esters. 1H NMR spectra were investigated to describe the binding mode of the recognition system, showing that all the protons of the guests were shifted to upfield. The circular dichroism spectra of 1-L-/D-ValOMe showed a split cotton effect in Soret region, while those of 1-L-/D-PheOMe showed no split cotton effect. Molecular modeling was performed to understand chiral recognition on a molecular level. Quantum chemical calculation was carried out based on the stable conformations of these recognition systems, which gave a reasonable explanation for the behavior of molecular recognition. The results indicated that the conformation of 1-D-ValOMe was more stable than that of 1-L-ValOMe.     

辅助电极对纳升电喷雾影响的研究

电喷雾质谱作为一种有效的软电离技术易于和各种液相分离技术如高效液相色谱以及毛细管电泳等技术实现在线联用,已越来越广泛地用于生物大分子的分析鉴定,但常规电喷雾技术要求分析试剂流速一般为1～10μL／min,耗样量大．因而低样品消耗、高灵敏的纳升电喷雾技术的研究越来越受到重视。纳升电喷雾技术因其喷雾头口径较小,产生的泰勒锥体也相应减小,样品分子的去溶剂化和离子化效率大大提高,有文献报道,利用纳升电喷雾技术可检测到10^-18mol级蛋白样品。     

单糖和二糖的定量分析的研究进展

综述了单糖和二糖的常用定量分析方法,如重量法、滴定法、旋光法、比色法,薄层扫描法、近红外光谱法、拉曼光谱法、气相色谱法、气相色谱-质谱联用法、液相色谱法、液相色谱-质谱联用法、离子色谱法和毛细管电泳法等,详细介绍了各方法的特点、应用及最新研究进展,并对其发展前景进行了展望。     

Surface active agents stabilize nanodroplets and enhance haze formation

Although many organic molecules found commonly in the atmosphere are known to be surface-active in aqueous solutions, their effects on the mechanisms underlying haze formation remain unclear. In this paper, based on a simple thermodynamic analysis, we report that the adsorption of amphiphilic organics alone not only lowers the surface tension,but also unexpectedly stabilizes nanodroplets of specific size under water vapor supersaturation. Then we determine how various factors, including relative humidity, water activity effect due to dissolution of inorganic components as well as surface tension effect due to surface adsorption of organic components, cooperatively induce the stability of nanodroplets.The nanodroplet stability behaviors not captured in the current theory would change the formation mechanism of haze droplets, from the hygroscopic growth pathway to a nonclassical two-step nucleation pathway.     

微电喷雾与纳电喷雾装置的制作

研制了实验室可自制的多种微／纳电喷雾喷头。喷头制作简单且易于操作,并利用利血平标准样品测试了各种微／纳电喷雾喷头的性能,显示了其高灵敏、低消耗的显著特点。     

固相萃取净化-超高效液相色谱-三重四极杆质谱法测定土壤中草铵膦、草甘膦及其代谢物氨甲基膦酸

建立了固相萃取净化-超高效液相色谱-三重四极杆质谱法测定土壤中草铵膦、草甘膦及其代谢物氨甲基膦酸含量的方法.将土壤样品与水、二氯甲烷混合后,高速匀浆1 min后离心,取上清液3 mL过Oasis HLB固相萃取小柱,收集最后1 mL的流出液,过0.22μm滤膜.用超高效液相色谱-三重四极杆质谱测定滤液中的草铵膦、草甘膦...