联用技术测定富硒农产品中硒的形态研究进展

硒的营养功能与农产品硒的形态息息相关。联用技术作为元素形态分析的有效方法,近年来受到了人们广泛关注。对用联用技术测定富硒农产品中硒的形态研究现状及进展进行了综述,包括前处理技术、色谱分离技术和定量检测方法等3个方面。     

HPLC-ICP-MS在食品中硒和砷形态分析及其生物有效性研究中的应用

食品中含有与人体健康密切相关的多种微量元素,微量元素的毒性和生物有效性取决于它们的化学形态。食品中的微量元素形态分析及其生物有效性研究对食品安全控制与营养评价具有至关重要的意义。本文扼要介绍了高效液相色谱与电感耦合等离子质谱（HPLC-ICP-MS）联用情况,该技术以不同的色谱分离柱完成各种分析物的分离,具有高灵敏度、高选择性、线性范围宽、检测限低、多元素同时检测等特点,在微量元素形态分析中占有重要的地位。综述了HPLC-ICP-MS在食品微量元素形态分析及其生物有效性研究中的应用,重点介绍了富硒酵母、蒜类植物、富硒营养保健品等食品中硒形态和海产品、农产品等食品中砷形态的研究,以及其它多种微量元素的形态分析和这些微量元素在生物体内的代谢。     

联用技术在植物硒形态分析中的应用

介绍了植物中硒形态分析的意义,植物中硒存在的形式;综述了植物中硒形态分析时,采用的萃取、液相色谱、气相色谱、电泳和毛细管电泳等样品分离技术;电感耦合等离子体质谱、同位素稀释-质谱、电感耦合原子发射光谱及电喷雾质谱分析方法,引用文献51篇.     

硒化合物的形态分析进展

硒的毒性和营养功能不仅与其总量有关,而且与其存在的化学形态有关,因此,硒的形态分析对于了解不同形态的硒化物在生物体和环境中的迁移转化规律具有重要意义。综述了硒化合物的不同形态和分析方法和技术。     

生物样品中硒的测定方法及形态分析研究进展

硒的毒性和营养功能不仅与其总量有关,而且与其存在的化学形态有关。因此,硒的测定及形态分析对于了解不同形态的硒化物在生物体和环境中的迁移转化规律具有重要意义。文章综述了生物样品中硒的测定分析方法以及形态分析研究进展。     

高效液相色谱-电感耦合等离子质谱分析烟草中硒形态

采用高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)联用技术建立了烟草中硒的形态分析方法。烟草样品采用0.10mol/L HCl超声提取30min,经离心、过膜后引入HPLC-ICP-MS进行分析。使用Hamilton PRP X-100阴离子交换柱,以20mmol/L柠檬酸水溶液为流动相(pH=7.0),流速1.2mL/min,优化条件下实现了6种硒形态的分离。质谱采用He碰撞模式,硒代胱氨酸、亚硒酸根、甲基硒代半胱氨酸、硒酸根、硒脲、硒代蛋氨酸检出限分别为1.20、0.34、1.65、0.13、3.25和0.65ng/mL。该方法操作简单、快速、灵敏度高,精密度好,加标回收率在86.1%~95.8%之间,适用于烟草中硒元素形态分析。     

富硒木耳中的硒元素形态分析

以富硒木耳为研究对象,采用液相色谱偶联电感耦合等离子体质谱,分析比较了6种不同提取方法对富硒木耳中小分子硒形态的提取效率,对木耳的硒形态进行了定量分析。结果表明,对富硒木耳中的小分子硒形态的提取,胃蛋白酶提取法效果最好,提取率为44. 8%,其他溶剂从提取效果由好到差分别为:乙酸铵、柠檬酸、稀盐酸、50%的甲醇水溶液和70℃的热水。胃蛋白酶法提取的小分子硒形态主要为硒代蛋氨酸,其他硒形态,如硒代胱氨酸和四价硒,含量均很低,且不存在六价硒形态。     

HPLC-ICP-MS联用技术在富硒金针菇硒的形态分析中的应用

从富硒培养的金针菇中分离得到含硒化合物, 并采用SE-HPLC-ICP-MS联机技术对浸提液中的含硒化合物进行分离分析; 同时对样品中的硒蛋白在特定条件下水解, 采用RP-HPLC-ICP-MS联机技术对水解液中硒代氨基酸进行确认, 并测定其中硒的含量. 结果表明, 可溶态硒是富硒金针菇中硒的主要存在形式, 其中小分子含硒有机化合物中的含硒量占浸提液中硒的71.87%; 而含硒蛋白所占比例为4.88%; 进一步确定富硒金针菇中含有硒代胱氨酸、硒代蛋氨酸和由二者组成的含硒多肽等, 各形态硒的含量为总硒量的12.3%, 17.6%和36.8%. 本方法将具有高效分离能力的色谱技术与高灵敏度的元素检测技术成功结合, 用于含硒生物分子中硒的在线分析, 具有快速、灵敏及准确等特点.     

高效液相色谱-原子荧光光谱联用技术测定富硒鸡蛋中的硒形态

为监测市场上富硒鸡蛋中蛋清及蛋黄中硒形态的种类及分布规律,优化建立了一种高效液相色谱-氢化物发生-原子荧光光谱联用技术测定富硒鸡蛋蛋清及蛋黄粉中硒形态的方法。随机选取富硒鸡蛋样品,进行蛋清蛋黄分离、冷冻干燥及蛋黄脱脂处理,处理后样品经Tris-HCl缓冲液（5 mmol/L, pH=7.5）55 oC恒温振荡、酶解提取,高速离心机（10000 r/min）离心10 min,上清液过0.22 μm有机滤膜后采用高效液相色谱-氢化物发生-原子荧光光谱联用技术进行测定,外标法定量。结果表明,该方法能在11 分钟内实现5种硒形态的基线分离,且各种硒形态的线性相关系数(r)均大于0.9994,其检出限在0.5-3.0 μg/L之间,回收率在81.6%~110.4%之间,可以满足检测需求,按照该实验方法测定市场上富硒鸡蛋中的硒形态,方法灵敏度高、准确性好,且测得的富硒鸡蛋蛋清样品中硒形态主要成分为硒代蛋氨酸,而蛋黄样品主要成分为硒代半胱氨酸,还有少量的硒代蛋氨酸,同时,一些鸡蛋还含有极少量的亚硒酸根,但蛋清及蛋黄中硒代氨基酸的含量总和占总硒含量的83.3-98.4%,适用于富硒鸡蛋中的硒形态提取。由此可见,市场上富硒鸡蛋中的硒主要以硒代氨基酸的形式存在,比较适合日常补硒,且该方法可以对市场上富硒食品起到一定监测作用。     

环境样品中砷、硒形态分析研究进展

综述了近年来环境样品中砷、硒形态分析的研究进展,主要内容包括样品的前处理技术、分离技术、检测技术。前处理技术主要是用各种提取液采用各种方式提取样品中的砷、硒形态,分离技术主要有高效液相色谱分离、气相色谱分离、毛细管电泳分离等,检测技术主要有原子吸收光谱法、原子发射光谱法、原子荧光光谱法、电感耦合等离子体质谱法等。最后对其研究前景进行了展望。     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

物质分配系数的测定实验改进

实验教学目的是从解决实际问题出发,以实验技术训练和实验设计思想培养为目标。介绍了将单一的物质分配系数测定实验改进为综合实验,提高了实验效果及实验资源利用率。     

Calculation of enthalpies of hydrogenation of hydrocarbons

Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。