分散固相萃取气相色谱-负化学离子源质谱法测定大豆和玉米中20种农药的残留量

建立了一种大豆和玉米中20种农药残留量的分散固相萃取气相色谱-负化学离子源质谱分析方法。样品经乙腈提取并浓缩后加入N-丙基乙二胺（PSA）、石墨化碳黑和C18 3种填料进行分散固相萃取净化,气相色谱-负化学离子源质谱分时段选择离子监测技术测定与确证,外标法定量。所有农药在20～400 μg/L范围内线性均良好;方法的定量限(LOQ)均不高于2 μg/kg;在5,10和20 μg/kg 3个添加水平下所有农药的平均回收率均处于70%～130%之间,相对标准偏差(RSD)低于17%;运用该方法检测大豆和玉米样品时没有干扰现象。     

H2S气敏电极的研制、性能及其初步应用

本文报告了用全固态Ag₂S电极做指示电极和全固态氟离子电极做参比电极所研制的H₂S气敏电极的结构、性能及其在印染污水分析中的初步应用。电极的线性范围5×10^-8-1×10^-2MS^2-,响应快,重现性较好。除浓度较高的CN^-、I^-和CNS^-有干扰外,其他常见阴离子无干扰。对印染污水用电极悬空测定(加入稀释法),试液不需任何处理,也不沾污电极。方法简便、快速,能满足控制分析要求。     

基于P3近似的空间分辨漫反射研究

光源附近组织的空间分辨漫反射是近年来生物医学光子学领域的一个研究热点,其目的是发展一种能够测定活体生物组织光学参量的新技术。漫射近似理论研究光源附近组织的空间分辨漫反射具有很大局限性。P3近似理论考虑了相函数的三阶矩,能较准确地描述光源附近组织的光辐射分布。研究了基于P3近似的空间分辨漫反射,从输运理论的PN方程组出发,导出了P3近似方程组和P3近似的格林函数解;阐述了漫射近似与P1近似的关系,给出了外推边界条件下,准直光束近似后的P3近似漫反射率的完整表示,讨论了相函数二阶参量对P3近似漫反射的影响,并与漫射近似和蒙特卡罗模拟结果进行了比较,指出了P3近似的应用范围。     

2-溴代对苯二甲酸根桥联双核钴(Ⅱ)配合物的合成、磁性及抗癌活性

合成了三种以２－溴代对苯二甲酸根为桥联配体的新型双核钴（Ⅱ）的配合物，即［Ｃｏ２（ＢＴＰ）（ｐｈｅｎ）４］（ＣｌＯ４）２·Ｈ２Ｏ（配合物１）、［Ｃｏ２（ＢＴＰ）（Ｎｐｈｅｎ）４］（ＣｌＯ４）２·２Ｈ２Ｏ（配合物２）和［Ｃｏ２（ＢＴＰ）（Ｂｐｙ）４］（ＣｌＯ４）２·２Ｈ２Ｏ（配合物３）（ＢＴＰ＝２－溴代对苯二甲酸根，ｐｈｅｎ＝１，１０－菲罗啉，Ｎｐｈｅｎ＝５－硝基－１，１０－菲罗啉，Ｂｐｙ＝２，２′－联吡啶）。使用元素分析、ＩＲ、ＵＶ－Ｖｉｓ光谱和电导测定方法对该配合物进行了表征。测定了配合物的变温磁化率，并对所得数据进行了理论分析，求得了配合物１、配合物２和配合物３的自旋磁交换积分分别为：２Ｊ＝－６．５ｃｍ－１，２Ｊ＝－７．８ｃｍ－１和２Ｊ＝－８．９ｃｍ－１。对该三配合物进行了体外抗人白血病癌细胞的实验。发现该三配合物均具有一定的抑制癌细胞的活性     

Influence of high-order optical parameters of tissue on spatially resolved reflectance in the region close to the source

Influences of the scattering phase functions on spatially resolved diffuse reflectance from a homogenous semi-infinite medium close to source are studied with Monte Carlo simulation. It is shown that the influences of optical parameters higher than the second order on the diffuse reflectance are quite weak in the region from 0.3 to several transport mean free pathes when Henyey-Greenstein phase function or a combined phase function of two parameters are used. But this influence may be substantial if the double Henyey-Greenstein function is used to describe the scattering property of tissue.     

Targeted analysis and determination of β‐agonists,hormones, glucocorticoid and psychiatric drugs in feed by liquid chromatography with electrospray ionization tandem mass spectrometry

A comprehensive strategy combining a quantitative method was developed for 30 banned drugs including β‐agonists, hormones, glucocorticoid and psychiatric drugs in swine and chicken feeds. This rapid, simple and effective extraction method was based on matrix solid‐phase dispersion and electrospray ionization tandem mass spectrometry. The quantitative method was validated after previous statistical optimization of the main parameters of matrix solid‐phase dispersion. The limit of quantification of dopamine hydrochloride, chlormadinone acetate, melengestrol acetate, testosterone propionate, nandrolone and midazolam was 2 μg/kg and that of the other 24 drugs was 1 μg/kg. The recoveries of β‐agonists, hormones, glucocorticoid and psychiatric drugs spiked in swine and chicken feeds at a concentration range of 1–8 μg/kg were above 70.1% with inter‐day relative standard deviations less than 15.8%. The analytical strategy was applied to 100 feed samples collected from a local market in Wuhan (China). Clenbuterol, ractopamine and melengestrol acetate were identified and quantified at the level 0.2～3.5 μg/kg. The rapid and reliable method can be used to efficiently separate, characterize and quantify the residues of 30 banned drugs in swine and chicken feeds with advantages of simple pretreatment and environmental friendly nature.     

Metabolism of olaquindox in rat liver microsomes: structural elucidation of metabolites by high-performance liquid chromatography combined with ion trap/time-of-flight mass spectrometry

Olaquindox (N-(2-hydroxyethyl)-3-methyl-2-quinoxalincarboxamide-1,4-dioxide) is a growth-promoting feed additive for food-producing animals. Its toxicity is closely related to the metabolism. The complete metabolic pathways of olaquindox are not revealed. To improve studies of the metabolism and toxicity of olaquindox, its biotransformation in rat liver microsomes and the structure of its metabolites using high-performance liquid chromatography combined with ion trap/time-of-flight mass spectrometry (LC/MS-ITTOF) were investigated. When olaquindox was incubated with an NADPH-generating system and rat liver microsomes, ten metabolites (M1-M10) were detected. The structures of these metabolites were identified from mass spectra and comparison of their changes in their accurate molecular masses and fragment ions with those of the parent drug. With the high resolution and good mass accuracy achieved by this technique, the elemental compositions of the metabolites and their fragment ions were exactly determined. The results indicate that the N --> O group reduction is the main metabolic pathway of olaquindox metabolism in rat liver microsomes, because abundant 1-desolaquindox (M2), 4-desolaquindox (M1) and bisdesoxyolaquindox (M9) were produced during the incubation step. Seven other minor metabolites were revealed which were considered to be hydroxylation metabolites, based on the position of the quinoxaline ring or 3-methyl group and a carboxylic acid derivative on the side chain at position 2 of the quinoxaline ring. Among the identified metabolites, five new hydroxylated metabolites (M3-M7) were found for the first time in rat liver microsomes. This work will conduce to complete clarification of olaquindox metabolism, and improve the in vivo metabolism of olaquindox in food animals.     

The Study of a Disposable Reagentless Biosensor for Fast Test of Aspartate Aminotransferase

A reagentless biosensor for amperometric measurement of aspartate aminotransferase (AST) has been developed. The three‐electrode biosensor was modified with two enzyme membrane with an integrated planar Ag|AgCl reference electrode. With a cellulose membrane containing catalytic substance coated, the reagentless biosensor was used for measurement of serum AST. The optimal sensitive membrane composition and operation conditions were studied. With low polarizing potential (0 V vs. integrated Ag|AgCl) and appropriate substrate concentration (20 mM α‐ketoglutarate acid), the response of the biosensor to AST activity was linear over the range of 25–1000 U/L with good relativity (R=0.9904 and 0.9823 in standard AST solutions and AST serum respectively) and fast response time (120 s). The biosensor also indicated good stability of more than 90% of its original activity for 60 days stored in 4 °C, and 90% of the activity was retained after a storage period of 15 days at room temperature (25 °C). The biosensor is expected to be used for the diagnosis of heart and liver disease in the future.     

Reversible lithium intercalation in disordered carbon prepared from 3,4,9,10-perylenetetracarboxylic dianhydride

The electrochemical properties of the 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA)-based carbon, synthesized by directly pyrolyzing PTCDA under an argon gas flow, have been firstly explored as an anode material for lithium-ion batteries. PTCDA is decomposed in a single-step reaction, which was completed around 650 °C. X-ray diffraction studies indicated a disordered carbon structure, and scanning electron microscopy (SEM) results revealed that this PTCDA-based carbon had a pillar-like morphology with a diameter of approximately 1–4 μm and length of 5–20 μm. Electrochemical measurements showed that it delivered lithium insertion and deinsertion capacities of 496 and 311 mAh g⁻¹, respectively, during the first cycle. The charge capacity retention from the 1st to the 50th is 93.2% with an average capacity fade of 0.14% per cycle. The coulombic efficiency of the Li insertion/deinsertion processes reached 99% after five cycles.     

Crystal structure and ferromagnetic properties of the oxamidato-bridged Cu(II)–VO(IV) complex containing macrocyclic ligands

The novel oxamidato-bridged dinuclear [(CuL)VO(H₂O)(C₂O₄)] complex incorporating a macrocyclic oxamide has been synthesized, spectroscopically, structurally, and magnetically characterized, where (CuL = [5,6: 14,15-dibenzo-1,4,8,12- tetraazacyclopentadeca-7,13-diene-2,3-dione(2-)]copper(II)). Magnetic measurements indicate ferromagnetic interaction between Cu(II) and VO(IV) ions within the complex.