超高效液相色谱法快速测定环境空气中13种醛酮类化合物

建立了一种快速、高效分离测定环境空气中13种醛酮类化合物的方法。环境空气中的醛酮类化合物,与采样管中的2,4-二硝基苯肼在强酸性条件下反应生成腙类衍生物。洗脱的衍生物,以乙腈-水为流动相,采用Core-Shell型色谱柱进行分离,二极管阵列检测器检测。在优化的色谱条件下,13种醛酮组分的衍生物在15 min内均达到良好分离,各组分的质量浓度在50～1 000μg/L(以醛酮计)范围内与色谱峰面积线性相关系数均大于0.999。采样体积为50 L时,方法检出限为0.24～1.38μg/m³。样品加标回收率为92.9%～105%,测定值的相对标准偏差为1.2%～7.8%(n=6)。该方法分离快速、定量准确,满足环境空气中痕量醛酮类化合物的分离分析。     

超高效液相色谱法同时测定盐酸丁丙诺啡舌下含片中丁丙诺啡和纳洛酮的含量

建立了同时检测丁丙诺啡和纳洛酮的超高效液相色谱的分析方法.分析柱为Waters Acquity BEH C18超高效液相色谱柱,紫外检测波长为280 nm,流动相为甲醇-甲酸(0.2%)水,梯度洗脱,两种分析物在3 min内即可达到良好分离.纳洛酮和丁丙诺啡的线性范围分别为1～25 μg/mL,2～50 μg/mL,线性相关系数分别为0.9992,0.9995.检出限为0.2μg/mL.考察了甲醇和乙腈两种流动相体系对样品的分离效果,发现甲醇流动相体系的响应高于乙腈流动相体系.在优化条件下,对丁丙诺啡舌下含片以及加标后样品进行测定,且对其方法学进行考察,加标平均回收率在91.3%～100.1%之间,RSD小于5%.     

硅基高交联磺化PS-DVB固定相的混合模式色谱性能考察

对自制的硅基高交联磺化PS-DVB混合模式反相强阳离子交换固定相的色谱性能进行了考察。通过改变流动相条件:在反相色谱中,分离了5种疏水性化合物;在离子交换色谱中,分离了4种碱性有机化合物。考察了流动相中缓冲盐浓度、p H和乙腈浓度对溶质保留时间的影响。结果表明,该固定相既具有强阳离子交换作用,又兼有疏水相互作用。通过改变色谱分离模式,可实现亲水性或疏水性化合物的分离。可作为现有液相色谱模式的一种补充,为复杂样品的分离提供技术参考。     

气相色谱法测定费托合成水相产物中的低碳醇、醛、酮化合物

建立了铁基催化剂费托合成反应水相产物中低碳(C₁~C₈)醇、醛、酮的气相色谱测定方法.对色谱分离条件进行了优化,确立了以乙醇为基准物质并结合各组分校正因子的定量方法;考察了方法的精密度和准确度,并对费托合成反应水相产物样品进行了测定.结果表明,乙醇在不同的含量范围内呈现良好的线性关系,相关系数均大于0.99.费托合成水相产物中的加标回收率在93.4%~109.6%之间,准确性可以满足实际分析的需要.实际费托合成水相产物的分析结果表明,费托合成水相产物中主要的低碳醇、醛、酮的总质量分数约为3%~12%,乙醇含量最高(约为1.7%~7.3%),且正构醇、异构醇和醛酮类化合物所占的总比率依次降低.该方法简单、快速,对费托合成水相产物中重要组分的分析有重要意义.     

超高效液相色谱法测定餐饮油烟中的十五种醛酮

采用在流动相中添加四氢呋喃的方法来改善丙烯醛-2,4-二硝基苯肼(DNPH)和丙酮-DNPH的分离,然后优化流动相比例和梯度,确定了UPLC分析醛酮-DNPH的色谱条件。有机溶剂消耗量和分析时间分别是传统方法的1/20~1/10和12%~30%;工作曲线线性相关系数、方法检出限和测定下限均满足HJ683-2014的规定;UPLC法测定醛酮的2,4-二硝基苯肼衍生物的平均回收率为91.5%~101%。基于常规的超高效反向C18色谱柱,在40℃条件下建立了高效分离醛酮混标的UPLC方法,方法已用于测定餐饮油烟中醛酮类化合物。     

某些酚类的高温液相色谱行为

建立了高温液相色谱系统,在高温条件下,采用甲醇-水作为流动相,在Polymerx RP-1聚合物(PSDVB)色谱柱上考察了6种酚类样品的色谱行为.实验条件:温度40～160 ℃,流速0.2～5.5 mL/min,流动相中甲醇浓度范围40%～80%.考察了温度、流速和流动相组成对酚类样品的保留、分辨、柱效和系统压力的影响,探讨了酚类样品在聚合物柱上的热力学行为.温度升高2.35℃大约相当于流动相中甲醇浓度增加1%,可以通过改变色谱柱温度调节样品保留和改变选择性.柱温升高,降低了流动相的粘度,允许在高温条件下使用较高的流速实现快速分离.在160℃、V(甲醇):V(水)=40:60,为流动相和3 mL/min流速条件下,可于2.5 min内实现6种酚类的完全分离.     

微柱高效液相色谱法分离八角茴香挥发油成分

利用微柱高效液相色谱法(μ-HPLC)对八角茴香果实挥发油成分进行了分离,对固定相类型、流动相组成及流速等条件进行了优化。结果表明,选用氰基分析柱(250mm×0.32mmi.d.,5μm),正己烷-乙腈-二氯甲烷(80∶8∶12,体积比)为流动相,流速为2μL·min-1,八角茴香果实挥发油成分在微柱液相色谱上分离效果最好。在优化的实验条件下,对实际样品中反式-茴香醚、茴香醛等成分进行了定量。本实验为以后的μ-HPLC与毛细管气相色谱联用分析植物挥发油奠定了基础。     

高效液相色谱法测定生物组织中的组胺

通过比较各种分析柱的分离效果,建立了用离子交换柱分离,邻苯二甲醛柱后衍生荧光检测分析生物组织中组按的液相色谱方法,并对流动相的离子强度和ＰＨ进行了优化,确定了４０ｍｍｏｌ／ＬｐＨ５．５０的柠檬酸钠缓冲液作为流动相为最佳条件。分析时间缩短为１５ｍｉｎ。     

超高效液相色谱-串联四极杆质谱法对N-甲基氧化吗啉及其降解产物的检测

建立了N-甲基氧化吗啉(NMMO) 及其降解产物吗啉、N-甲基吗啉、N-亚硝基吗啉的超高效液相色谱-串联四极杆质谱联用的分析方法.以Waters Acquity BEH C18超高效液相色谱柱为分析柱,乙腈-氨水为梯度洗脱液,4种分析物在3 min内即可达到良好分离;经串联四极杆质谱多反应监测模式检测,4种物质的线性范围为10 ～500 μg/L,检出限为1 ～10 μg/L.考察了酸性、碱性两种流动相体系对样品的分离效果,发现碱性流动相体系的分离效果优于酸性流动相体系,同时发现质谱响应信号随着流动相pH值的增大而减小.在优化条件下,对实际样品以及加标后样品进行测定,结果满意,该方法适合大批量Lyocell纤维纺丝凝固浴等样品的测定以及NMMO的出口检测.     

高效液相色谱法测定卷烟滤嘴对主流烟气中低分子醛酮化合物的截留效率

用高效液相色谱法测定了用过的烟嘴中8种低分子醛酮化合物,据此对烟嘴从主流烟气中截留8种化合物的效率。烟嘴样品用衍生试剂溶液与甲醇(10+90)混合液30 mL萃取10min,分取适量萃取液供高效液相色谱分析。以DIONEX Explosives色谱柱为分离柱,用乙腈和水以不同比例混合的溶液为流动相进行梯度洗脱,在检测波长365nm处进行测定。8种低分子醛酮化合物在一定质量浓度范围内与其峰面积呈线性关系,方法的检出限(3s)在0.07~0.15mg·L-1之间。加标回收率在85.1%~102%之间,测定值的相对标准偏差(n=5)小于6.8%。     

Analysis and assessment of the occurrence, the fate and the behavior of nanomaterials in the environment

Nanomaterials have one dimension <100 nm and possess physico-chemical properties dictated by their unusually small size, large surface area, shape and chemical composition. New properties of nanomaterials have boosted their production and industrial applications in many fields (e.g., microelectronics, catalysis, fuel cells, materials science, textiles, biotechnology and medicine). In biomedical fields, nanomaterials are of the appropriate dimensions to interact with biological matter. However, they may also have negative effects on biological systems. Nanotechnology is a major, innovative, scientific and economic growth area, but the increasing production and use of nanomaterials have led to calls for more information regarding the potential impacts that their release may have on human health and the environment.This review addresses analytical approaches for characterization and quantification of nanomaterials in the environment and recent studies on their occurrence, fate and behavior.     

The energy pump and the origin of the non-equilibrium flux of the dynamical systems and the networks

The global stability of dynamical systems and networks is still challenging to study. We developed a landscape and flux framework to explore the global stability. The potential landscape is directly linked to the steady state probability distribution of the non-equilibrium dynamical systems which can be used to study the global stability. The steady state probability flux together with the landscape gradient determines the dynamics of the system. The non-zero probability flux implies the breaking down of the detailed balance which is a quantitative signature of the systems being in non-equilibrium states. We investigated the dynamics of several systems from monostability to limit cycle and explored the microscopic origin of the probability flux. We discovered that the origin of the probability flux is due to the non-equilibrium conditions on the concentrations resulting energy input acting like non-equilibrium pump or battery to the system. Another interesting behavior we uncovered is that the probabilistic flux is closely related to the steady state deterministic chemical flux. For the monostable model of the kinetic cycle, the analytical expression of the probabilistic flux is directly related to the deterministic flux, and the later is directly generated by the chemical potential difference from the adenosine triphosphate (ATP) hydrolysis. For the limit cycle of the reversible Schnakenberg model, we also show that the probabilistic flux is correlated to the chemical driving force, as well as the deterministic effective flux. Furthermore, we study the phase coherence of the stochastic oscillation against the energy pump, and argue that larger non-equilibrium pump results faster flux and higher coherence. This leads to higher robustness of the biological oscillations. We also uncovered how fluctuations influence the coherence of the oscillations in two steps: (1) The mild fluctuations influence the coherence of the system mainly through the probability flux while maintaining the regular landscape topography. (2) The larger fluctuations lead to flat landscape and the complete loss of the stability of the whole system.     

McBain and the centenary of the micelle

In 1913, J.W. McBain introduced the word “micelle” into surface and colloid chemistry in the context of the association of surfactant molecules in aqueous solution. This article gives a biographic account of McBain, and reviews the early work on micellar aggregation, leading up to the pioneering ideas of G.S. Hartley who introduced the first model of the spherical micelle that we would recognise today.     

Use of Isotope Effects To Understand the Present and Past of the Atmosphere and Climate and Track the Origin of Life

Stable isotope ratio measurements have been used as a measure of a wide variety of processes, including solar system evolution, geological formational temperatures, tracking of atmospheric gas and aerosol chemical transformation, and is the only means by which past global temperatures may be determined over long time scales. Conventionally, isotope effects derive from differences of isotopically substituted molecules in isotope vibrational energy, bond strength, velocity, gravity, and evaporation/condensation. The variations in isotope ratio, such as ¹⁸O/¹⁶O (δ¹⁸O) and ¹⁷O/¹⁶O (δ¹⁷O) are dependent upon mass differences with δ¹⁷O/δ¹⁸O=0.5, due to the relative mass differences (1 amu vs. 2 amu). Relations that do not follow this are termed mass independent and are the focus of this Minireview. In chemical reactions such as ozone formation, a δ¹⁷O/δ¹⁸O=1 is observed. Physical chemical models capture most parameters but differ in basic approach and are reviewed. The mass independent effect is observed in atmospheric species and used to track their chemistry at the modern and ancient Earth, Mars, and the early solar system (meteorites).     

New study of the stability and of the spectroscopy of the molecular anions NCO- and CNO-

Using highly correlated wave functions, the ground and the low lying excited states of the molecular NCO(-) and CNO(-) anions have been reinvestigated. The stability of the electronic ground state of the two isomers with respect to dissociation and to electron detachment has been checked along the isomerization pathway. The regions of stability of the excited electronic states have been analyzed and identified and it is shown that only the ground state is stable and the corresponding potential energy surface presents three equilibrium positions. The rovibronic spectroscopy of the X (1)Σ(+) state of both NCO(-) and CNO(-) isomers has been determined by a variational approach leading to remarkable agreement with experimental data.     

Influence of the molecular structure and the nature of the solvent on the absorption and fluorescence characteristics of rhodamines

A study of the equilibrium of the molecular forms of rhodamine 19 in aqueous and ethanolic solution is carried out by determining the absorption and fluorescence characteristics of the zwitterionic and the cationic forms of the dye. The optical properties of rhodamine 19 are compared with those obtained for rhodamine 6G and also with those previously reported for rhodamine 3B and for the molecular forms of rhodamine B in water and ethanol. Different aspects of the molecular structure of the rhodamines and solvent effects are discussed, as well as their influence on the photophysical properties of the rhodamines. The aggregation of the molecular forms of rhodamine 19 is also studied in water and ethanol.     

Synthesis and pharmacological effects of the enantiomers of the N-phenethyl analogues of the ortho and para e- and f-oxide-bridged phenylmorphans

The N-phenethyl analogues of (1R*,4aR*,9aS*)-2-phenethyl-1,3,4,9a-tetrahydro-2H-1,4a-propanobenzofuro[2,3-c]pyridin-6-ol and 8-ol and (1R*,4aR*,9aR*)-2-phenethyl-1,3,4,9a-tetrahydro-2H-1,4a-propanobenzofuro[2.3-c]pyridin-6-ol and 8-ol, the ortho- (43) and para-hydroxy e- (20), and f-oxide-bridged 5-phenylmorphans (53 and 26) were prepared in racemic and enantiomerically pure forms from a common precursor, the quaternary salt 12. Optical resolutions were accomplished by salt formation with suitable enantiomerically pure chiral acids or by preparative HPLC on a chiral support. The N-phenethyl (-)- para-e enantiomer (1S,4aS,9aR-(-)-20) was found to be a mu-opioid agonist with morphine-like antinociceptive activity in a mouse assay. In contrast, the N-phenethyl (-)-ortho-f enantiomer (1R,4aR,9aR-(-)-53) had good affinity for the mu-opioid receptor (K(i) = 7 nM) and was found to be a mu-antagonist both in the [(35)S]GTP-gamma-S assay and in vivo. The molecular structures of these rigid enantiomers were energy minimized with density functional theory at the level B3LYP/6-31G* level, and then overlaid on a known potent mu-agonist. This superposition study suggests that the agonist activity of the oxide-bridged 5-phenylmorphans can be attributed to formation of a seven membered ring that is hypothesized to facilitate a proton transfer from the protonated nitrogen to a proton acceptor in the mu-opioid receptor.