毛细管电泳用于水产品中五种抗生素的同时测定

用毛细管电泳-紫外检测法同时测定水产品中的四环素(TC)、金霉素(CTC)、土霉素(OTC)、多西环素(DC)及氯霉素(CAP)的含量．研究了缓冲体系的酸度、浓度、添加剂、分离电压、进样时间以及温度等条件对分离的影响,得到了电泳的最优条件．在278nm波长处,分离电压为22kV,20mmol／L磷酸氢二钠-10mmol／L柠檬酸(pH值2．8,含0．25mmol／L Na2EDTA和体积分数为4．0％的吐温-80)运行缓冲液下,上述5种组份在25min内得到完全分离．5种抗生素的质量浓度和电泳峰面积在2．5～300．0mg／L和10．0～300．0mg／L范围内呈现良好的线性,TC、CTC、OTC、DC和CAP的相关系数(r)分别为0．9996、0．9992、0．9993、0．9934、0．9987,检测下限为0．5～1．5μg／mL。该方法灵敏度高,重现性好,操作简便,并已成功用于水产品鲫鱼中的5种抗生素残留的检测。     

毛细管电泳-电化学检测法用于中药石韦中绿原酸和槲皮素的同时测定

建立了毛细管电泳同时分离测定中药石韦中绿原酸、槲皮素含量的分析方法．采用柱端喷壁式三电极系统的电化学检测方式,工作电极为0．5mm碳圆盘电极;参比电极为．Ag／AgCl;辅助电极为铂丝电极．以70cm(o．d360μm．i.d25μm)的熔融石英毛细管为分离通道,在最佳电泳介质(pH=7．0,10．0mmol／L磷酸盐缓冲溶液)中,当分离电压为21kV时,两待测物质在8min内完全分离．在最佳分离、检测条件下,响应电流与浓度之间的线性关系良好,绿原酸、槲皮素的线性方程分别为：y=0．268x 1．088、y=0．312x 0．822,相关系数大于0．999,绿原酸、槲皮素检测限分别达0．075μg／mL和0．020μg／L该方法具有良好的重现性,峰电流的RSD小于3．5％．已成功的用于实际中药石韦和模拟血样中绿原酸、槲皮素的含量测定,结果令人满意．     

阻抑速差催化光度法测定痕量色氨酸和酪氨酸

研究了色氨酸、酪氨酸在硫酸环境中抑制碘对亚砷酸与硫酸铈氧化还原反应的催化作用及动力学条件。在0．001mol／L Ce(SO4)2,0．00125mol／L As2O3,0．013mg／L KI,0．025g／L和0．25g／L NaCl溶液中测定色氨酸和酪氨酸,其线性范围分别为0．0～0．65mg／L,0．0～4．0mg／L和0．0～1．3mg／L。0．10～4．0mg／L,用联立方程分别求出各自含量。用此法对醇溶蛋白质和混合氨基酸溶液中色氨酸和酪氨酸进行测定,混合氨基酸的色氨酸、酪氨酸测量值为0．8037g／L,3．591g/L;蛋白质的色氨酸、酪氨酸测量值为1．8g/kg、3．43g/kg;回收率在88％～109％;色氨酸和酪氨酸的RSD分别为4．8％和5．2％,结果满意。     

氢化物发生电感耦合等离子体原子发射光谱法同时测定水和生物样品中砷、铋、锑和硒

研究了一种小型同心氢化物发生器配置一个气液分离器后与多道ICP－AES联用，同时测定水和生物样品中砷、铋、锑、硒的方法。检出限为砷0.4μg/L，铋0.5μg/L，锑1．4μg／L，硒0.5μg／L，相对标准偏差为砷2.7％，铋1．5％，锑2．7％，硒1．9％。用本法测定美国和国家标准物质中的氢化元素，结果满意。     

胶束电动力学毛细管电泳分离和测定牡蛎中的氨基酸

采用胶束电动力学毛细管电泳,在25mmol／L Na2HPO4-NaH2PO4(pH7．0),40mmol／L十二烷基硫酸钠和3mol／L尿素的实验条件下,在28min内实现了牡蛎中8种游离丹酰化氨基酸的分离和测定。在一定浓度范围内,氨基酸的峰面积与其浓度呈良好的线性关系,相关系数0．9955～0．9984之间。对于8种氨基酸,标准加入回收率在99．5％～100．7％之间。     

高效液相色谱法测定火腿肠中的诱惑红

火腿肠经脱脂后,用乙醇-氨-水溶液提取色素,溶液经浓缩后,在酸性条件下用聚酰胺吸附,在碱性条件下解吸附,定容制成水溶液。以C18柱分离,用二极管阵列检测器检测,采用反相高效液相色谱法测定火腿肠中的食用合成色素诱惑红,回收率为85、8％～93．7％,测定结果的相对标准偏差为1．25％～2．39％,线性范围为1～100mg／L,检出限为0．5mg／kg。     

毛细管气相色谱法分离分析苯酚和水杨醛

采用毛细管气相色谱法对由苯酚和甲醛为原料合成的水杨醛及反应物苯酚进行了分离分析。研究了水杨醛与苯酚分离的最佳条件，用正十四烷作内标物进行定量，水杨醛、苯酚在0．5～6．0g／L内有良好的线性，加标平均回收率分别为97、3％、99、0％，测定结果的相对标准偏差小于5％。     

液相色谱与电感耦合等离子体原子发射光谱联用分离和检测四价和六价铀

通过液相色谱与电感耦合等离子体原子发射光谱的联用,可以快速同时分离和检测四价和五价铀的EDTA络合物。在使用16mmoL／LNa2CO3,4mmoL／LNaHCO,和10mmol／LEDTA的混合液作为洗脱液,Dionex AGl4 guard column作为分离柱,流速为2．0mL／min的色谱工作条件下对U（Ⅵ）和U(Ⅵ）的EDTA络合物进行分离,然后用配有常规V型槽玻璃雾化器的电感耦合等离子体原子发射光谱进行检测。在选定的分析线385．958nm的条件下,检出限对于U（Ⅵ）和U（Ⅵ）分别是1．0mg／L和1．5mg／L。使用超声雾化器,U（Ⅵ）和U（Ⅵ）的检出限可分别降低至0．10和0．25mg／L。该方法快速,简便,且干扰小。该法已成功的应用于合成样品的定量分析,回收率在95％以上。     

糊精介质中西酞普兰的毛细管电泳手性分离与定量测定

以糊精作为毛细管电泳手性分离选择剂,对药物西酞普兰对映体的分离进行研究。考察了糊精浓度、缓冲液体系离子强度和pH及分离电压对对映体分离的影响。在糊精7．0％（m／V）、磷酸盐80mmol／L（pH5．4）的运行缓冲液中,分离电压20kV时,西酞普兰对映体分离度达3．9,同时对拆分机理进行了初步探讨。测定S-（＋）-西酞普兰原料药中R-（-）异构体的含量,在0．05～4．00g／L浓度范围内线性关系良好,R-（-）．西酞普兰与S-（＋）-西酞普兰的检出限分别为25．3mg／L和27．3mg／L,线性相关系数均在0．9970以上;RSD低于3．2％。     

羟丙基-β-环糊精毛细管胶束电动色谱法测定密蒙花中的芹菜素和木犀草素

通过优化缓冲溶液pH和浓度、SDS浓度和β-CD等条件,建立了一种HP-β-CD毛细管胶束电动色谱法测定密蒙花中的芹菜素和木犀草素的方法。在优化的条件下,2种物质在15min内得到良好分离。木犀草素和芹菜素的峰高和浓度在0．01—0．60g/L范围内成良好线性。2种物质基于迁移时间和峰高的相对标准偏差分别为1．2％、1．9％和2．5％、2．8％。检出限分别为0．005和0．0045g／L。     

Stabilization Studies on Divalent Five‐Membered Rings C4H4C,C4H4Si,C4H4Ge,C4H4Sn,and C4H4Pb

Energy differences, ΔX_S‐t (X = E, H and G) (ΔX_S‐t = X_(singlet)‐X_(triplet)) between singlet (s) and triplet (t) states are calculated at B3LYP/6‐311++G (3df,2p). The DFT calculations show that the triplet state of C₄H₄C is a ground state with planar conformer respect to its corresponding nonplanar singlet state. Both singlet and triplet states of C₄H₄M (M = Si, Ge, Sn and Pb) have a planar conformer with the singlet ground state. Four isodesmic reactions are presented for determining the stability energies, SE. NICS calculations are carried out for C₄H₄M to determine the aromatic character.     

Effects of Base for the Efficient Synthesis of 4-Formylcoumarins and 4-Formylcarbostyrils

The first efficient transformation of 4-bromomethylcoumarins and 4-bromomethylcarbostyrils to 4-formylcoumarins and 4-formylcarbostyril under aqueous conditions has been achieved by modifying the Kornblum method, resulting in excellent yield. The experimental method is very simple and economical; no further purification is required and the experimental conditions have been optimized. All the isolated compounds were characterized by infrared, NMR, and mass spectroscopy, and some of the compounds have been analyzed by single-crystal x-ray analysis.     

NH4VO3在NH4H2PO4-H2O和(NH4)3PO4-H2O体系中的溶解度

采用等温溶解法测定了偏钒酸铵(NH₄VO₃)在NH₄H₂PO₄-H₂O和(NH₄)₃PO₄-H₂O体系中T = 298.15-328.15 K时的溶解度以及溶液的密度和pH值。结果表明, NH₄VO₃的溶解度随着(NH₄)₃PO₄或NH₄H₂PO₄溶液浓度的增大,先降低后升高,这是由于同离子效应、化学反应平衡及离子活度的共同作用。比较T = 298.15K时, NH₄VO₃分别在NH₄H₂PO₄-H₂O、(NH₄)₂HPO₄-H₂O和(NH₄)₃PO₄-H₂O体系中溶解度,发现在相同的磷酸盐浓度下, NH₄VO₃的溶解度在NH₄H₂PO₄-H₂O体系中最大,在(NH₄)₃PO₄-H₂O体系中居中,在(NH₄)₂HPO₄-H₂O体系中最小。进一步地,在T = 298.15 K和磷酸盐浓度C = 0.5 mol·kg^-1时,结合pH值和反应溶度积常数K_SP等计算三个体系中的平均离子活度系数(γ_±),发现γ_±值在(NH₄)₂HPO₄-H₂O体系中最大,在(NH₄)₃PO₄-H₂O体系中居中,在NH₄H₂PO₄-H₂O体系中最小,与溶解度规律一致。     

4-Silapiperidine and 4-silapiperidinium derivatives: syntheses and structural characterization

A series of novel 4-silapiperidine and 4-silapiperidinium derivatives, with two silicon-bound aryl groups and various N-organyl groups, have been synthesized and structurally characterized (solution ¹H, ¹³C, ¹⁹F, and ²⁹Si NMR spectroscopy; eight crystal structure analyses). These synthetic and structural investigations provide the basis for the development of novel silicon-based drugs containing a 4-silapiperidine or 4-silapiperidinium skeleton.     

A simple and efficient synthesis of optically pure 4-alkylisoxazolidin-4-ols

The reaction between N-hydroxyphthalimide and optically pure epichlorohydrin followed by addition of methanol represents a straightforward procedure for the synthesis of isoxazolidin-4-ols in high enantiomeric purity. Under the same conditions, the reaction of glycidyl arenesulfonates can lead to different products depending on the nature of the sulfonate. This property allowed the synthesis of both enantiomers of 4-methylisoxazolidin-4-ol from the same chiral epoxide starting material.     

2-烷硫基-5-苯基亚甲基-4H-咪唑啉-4-酮的合成与表征

用2-硫代-3-正丁基-5-苯基亚甲基4-咪唑啉二酮的-S-烷基化反应合成了2-烷硫基-3-正丁基-5-苯基亚甲基-4H-咪唑啉-4-酮衍生物。探讨了S-烷基化反应的反应条件和所合成化合物的波谱性质。目标产物均为新的化合物，其结构经元素分析，IR，1H NMR和MS确正。     

A new application of diphenylphosphorylazide (DPPA) reagent: convenient transformations of quinolin-4-one, pyridin-4-one and quinazolin-4-one derivatives into the 4-azido and 4-amino counterparts

Herein, we describe a transformation of the oxo-function of a series of quinolin/pyridin/quinazolin-4-ones into 4-azido and thence into 4-amino derivatives in moderate yields by a very short and convenient new procedure using DPPA (diphenylphosphoryl azide) as reagent. A mechanism for this interesting new application of DPPA is suggested based on the identification of some of the intermediates.     

Electronic structures of the boron cage molecules B4H4, B4Cl4 and B4F4

Ab initio calculations have been performed on B₄H₄, B₄Cl₄ and B₄F₄ in order to aid our understanding of the bonding in these compounds, which is presumably based on a tetrahedral boron cage. This cage has only 8 electrons and so is less than that expected on the basis of the usual framework electron counting rules. Basis sets with polarisation functions were used at the SCF, CI and CPF levels of theory to confirm that the T _d structures are indeed more stable than the D _4h ones. Davidson-Roby population analyses were able to show that many factors, including 3-centre 2-electron bonding and backbonding from the ligand to the boron cage, are of importance in determining the relative stability of the three compounds, of which B₄Cl₄ is the only one that has yet been observed experimentally.     

4,4'''',4″,4′″-四磺酸酞菁钼的合成和荧光特性

本文报道4,4′,4″,4′″-四磺酸酞普钼的一种新的固相合成法及其荧光特性。初步研究证明其量子产率高于四磺酸酞菁锌,在已知过渡金属酞菁配合物中最高。