佛尔哈德法测银催化剂中银含量

采用佛尔哈德法测银催化剂中银含量.称0.5g左右的试样,用20mL(1+1)硝酸溶解样品,加1mL硫酸铁铵饱和溶液指示剂,用0.05mol/L硫氰酸铵标准溶液滴定试样溶液,至溶液变为粉红色,激烈振荡30秒不褪色即为滴定终点.本实验测得试样银含量为16.84%,相对标准偏差为0.29%,加标回收率为99.5%～100.6%;采用Q/SY LYF0331-2003测得银含量为16.86%.该实验方法简便快捷,分析结果准确可靠,适用于银催化剂中银含量的测定.     

燃烧法测定丁腈橡胶中结合丙烯腈含量

采用燃烧法,通过元素分析仪测定了丁腈橡胶( NBR) 中结合丙烯腈含量,考察了试样制备条件及试样质量对测定结果的影响,分析了方法的精密度,并与凯氏定氮法测定结果进行了对比。结果表明,试样制备的适宜抽提时间和干燥时间分别为1. 0,2. 0 h,试样质量宜为2 mg; 该方法的相对标准偏差为 0. 24% ～ 0. 53%,精密度较好; 对于结合丙烯腈质量分数为20% ～ 40%的NBR,燃烧法测定结果与凯氏定氮法无显著性差异,稍高于凯氏定氮法,两者差值为1. 13% ～ 1. 64%,且测定时间缩短至15 min 左右。     

电位滴定法测定火药中硫酸钾含量

用电位滴定法测定了单基火药中的 K2 SO4 含量 ,结果表明 ,用丙酮溶解单基药试样 ,以 75 %的丙酮为滴定介质 ,测定结果的误差小于 2 % ,标准偏差为 0 .0 2 ;用浓硝酸破坏试样 ,以 70 %的乙醇为滴定介质 ,误差小于 0 .2 % ,回收率达 99.8%以上 ,标准偏差为0 .0 0 1     

云南磷矿石中氧化钙含量测定方法的改进

用国标EDTA容量法检测磷矿石中氧化钙含量时,存在终点难以判定等问题,实验研究改用钙羧酸作指示剂,用三乙醇胺掩蔽铁、铝和少量锰,用糊精作保护剂抑制磷酸根和镁的干扰,同时采用KOH溶液调节试样溶液的pH值≥13,用EDTA标准溶液滴定,终点颜色变化敏锐,测定氧化钙的结果准确,方法可靠。     

煤中总酸基的测定

介绍了煤炭腐植酸中含氧功能团的分析 ,即总酸基的测定。以电位中和滴定法进行测定 ,酸度计指示终点 ,并对样品处理进行了改进 ,对测定的最佳条件也进行了研究。该方法的相对标准偏差小于 1 .2 % ,加标回收率为 97.80 %～ 1 0 2 .50 %。方法已应用于实际样品的测定 ,结果令人满意。     

黄原酸钾含量的示波滴定

报道了用示波滴定法测定黄原酸钾含量 ,在 p H5～ 6的 HAc- Na Ac缓冲底液中 ,加入四苯硼钠 ( Na- TPB)沉淀 K+ ,过量的 Na- TPB用氯化四乙基铵标准溶液滴定 ,滴至 Na- TPB示波图切口消失为终点 ,终点直观敏锐 ,方法快速简便 ,准确度、精密度均高。标准加入回收率在 99.8%～1 0 0 .2 % ,RSD<0 .2 %     

烯唑醇含量分析方法的研究

烯唑醇含量分析试样用甲醇溶解 ,以邻苯二甲酸二乙酯为内标物 ,在ODS柱和紫外检测器上对试样中的烯唑醇进行高压液相色谱分离和测定。该方法定量准确 ,精密度较好 ,对烯唑醇原药同一样品进行十次重复测定 ,方法标准偏差为 0 .37,变异系数为 0 .38% ,回收率为 98.9%～ 10 0 .6 %。     

非水溶液滴定法测定依帕司他

本文采用非水溶液滴定法测定抗糖尿病症状新药依帕司他的含量，试样以二甲基甲酰胺溶液溶解，氢氧化四丁基铵为滴定剂，平均含量为100．48%，相对标准偏差为0．31%（n＝5）。本法具有消定终点灵敏度高，滴定突跃大，正确，再现性好等优点。     

研究动态

炼铜转炉风口用镁铬质耐火材料抗渣性能的改进　　目前 ,炼铜转炉风口采用直接结合和半再结合镁铬砖 ,铜渣和粗铜的渗透引起的结构剥落是其损坏的主要原因。日本研究了配料的临界粒度和粒度配比对镁铬砖抗渣性能的影响。试验制备了 4个试样 ,其化学组成相同 ,w(MgO)为 70 % ,w(Cr2 O3)为 13 %。试样 1为原用砖。试样 2、3和 4的临界粒度均为试样 1的 0 .7倍。试样 2的粒度配比与试样 1的相同 ,但试样 3的粗颗粒比试样 1的增加 10 % (中颗粒相应减少10 % ) ,试样 4的粗颗粒比试样 1的增加 2 0 % (中颗粒相应减少 2 0 % )。将试样砌于回转抗…     

流动注射分析和离子选择电极联用测定水的pH值

提出了用 FIA- ISE联用技术测定水的 p H值的方法。以 0 .5mol/L KNO3和 1 .0× 1 0 - 7mol/L Na H2 PO4作载液 ,在 p H 3.7～ 1 1 .7范围内有良好的线性关系 ,用于实际试样分析 ,结果良好。分析速度可高达每小时 1 50～2 0 0个试样 ,相对标准偏差为 0 .58%～ 2 .0 %。     

Preparation of alumina ultrafine powders through acrylamide,starch and glutaric dialdehyde mediated sol–gel method

Ultrafine alumina powders were synthesized through acrylamide (AM), starch and glutaric dialdehyde mediated aqueous sol–gel process, respectively. Sol and gel formed gradually during drying of the solution due to polymerization reaction between functional groups. The used AM, starch and glutaric dialdehyde could be applied to form perfect matrix for the entrapment of metal ions, giving rise to ultrafine crystalline alumina particles during heating treatment. Al₂O₃ nanoparticles with γ crystalline phase were obtained via heating treatment of the dried precursor in air. Then the γ phase transforms to α phase and pure α-Al₂O₃ powders could be obtained when the heating temperature was 1473 K. Our results provide a new way of aqueous sol–gel process.     

Convenience of immobilized Bacillus licheniformis α-amylase as time—temperature-integrator (TTI)

For the immobilization of Bacillus licheniformis α-amylase to porous glass beads, the performances of three possible linking agents, glutaric dialdehyde, benzoquinone and S-trichlorotriazine were assessed in respect of the protein yield, the enzymic activity and the thermostability of the immobilized enzyme. These three properties are to be evaluated in view of the possible use of the enzyme preparations as time–temperature-integrators (TTIs) for assessing the severity of heat pasteurization or sterilization processes of food or pharmaceuticals. All three linkers improved the enzymes's resistance to irreversible heat inactivation to a similar extent and in each case biphasic inactivation kinetics were observed, whereas the dissolved B. licheniformis α-amylase showed a simple first order decay. The immobilization yield, measured as protein per carrier weight, did not differ markedly for the three linkers, although the enzymic activity of the glutaric dialdehyde-linked enzyme was lower than that of the benzoquinone- and S-trichlorotriazine-linked preparations.     

球形壳聚糖固定化糖化酶的研究

研究了以球形壳聚糖作载体固定化糖化酶的方法，探讨了戊二醛用量，酶量，温度，pH值对固定化效果的影响。     

一次性有机磷电化学生物传感器的研究

构筑了乙酰胆碱酯酶／Nafion／丝网印刷电极（AChE/Nafion／SCE）修饰电极,研究该修饰电极在羧酸二茂铁与羧酸二茂铁和氯化乙酰巯基胆碱混合溶液中的电化学行为,建立测定有机磷农药-马拉硫磷的计时电流法。该传感器与固体电极所制传感器相比,具有制备简单,灵敏度高,体积小,使用简单,酶膜稳定不易脱落,测量电流稳定,制造成本低等优点。     

氨苄西林磁性明胶药物微球的制备及控制释放

将药物封装入一个输送系统,以便在适当时间内持续控制药物释放.为此,利用明胶的生物相容性,选用难溶性氨苄西林(AMP)为药物模型,Fe3O4作为磁性内核,戊二醛作交联固化剂,液体石蜡为有机分散介质,采用反相悬液冷冻凝聚法(RPSCC)制备出了磁性AMP明胶核壳微球.用SEM、FT-IR和UV/Vis光谱等考察了药物微球的结构和外观形貌,以及药物在包封后的性质.结果表明磁性明胶药物微球的粒径小于20 μm.氨苄西林微球载药率(w/w)为7.1%,Fe3O4的含量为22.1%,微球包裹率为65.13%.7h内释放的药物占总含药量的72.3%.微球的缓释性能良好.     

Preparation and characteristics of polymer-based large adsorbent particles

Using polyvinyl alcohol (PVA) crosslinked with glutaric dialdehyde (c-PVA) as matrix and activated carbon (AC) or crosslinked polyacrylic acid (PAA) as the adsorptive constituent, large beads of c-PVA-AC and c-PVA-PAA composites were prepared via the sedimentation polymerization method. In this method, an aqueous solution of PVA, glutaric dialdehyde, and a catalyst for crosslinking (hydrochloric acid), containing activated carbon or the precursors of the crosslinked polyacrylic acid was injected dropwise with a syringe into hot mineral oil (about 80–90°C) located in a cylindrical reactor fit with a stirrer near its bottom. Partial gelation took place during the sedimentation process. This ensured that the particles arrived at the bottom of the column, where they were kept about 30–60 min to complete their polymerization, maintained their individuality without aggregation. The particle size was as large as about 3 mm. The adsorption characteristics of the two types of adsorbents were dependent on their AC or PAA content. Their adsorption capacity for four dyes was investigated. The c-PVA-AC and c-PVA-PAA had, at room temperature, saturation adsorption capacities as large as 84 and 104 mg/g for the basic Chrysoidin dye, and 70 and 72 mg/g for the basic Bismarck brown Y dye. © 1996 John Wiley & Sons, Inc.     

Biocatalitic Oxidation of 2,3,6-Trimethylphenol Over Immobilized Horseradish Peroxidase in Nonaqueous Media

In this work various samples of horseradish peroxidase immobilized over organic and inorganic supports were synthesized and studied in 2,3,6-trimethylphenol biocatalitic oxidation. Silica, alumina and commercial samples of polymers MN-100, Sepabeads EC-HA were used as the carriers for horseradish peroxidase. Different methods of immobilization including treatment with chitosan, glutaric dialdehyde and carbodiimide were used to enhance catalytic activity. For synthesized catalysts optimal conditions for 2,3,6-trimethylphenol (main intermediates in vitamin E synthesis) oxidation providing high degree of conversion (more than 95%) and high selectivity to target products (more then 98%) were found. Physicochemical investigations (FTIR spectroscopy, XPS, nitrogen physosorption) of optimal biocatalytic systems were provided.     

新型改性骨胶对甲醛吸附性能及机理研究

以柠檬酸对骨胶进行水解,并以戊二醛作为交联剂,制备出一种新型改性骨胶。研究了改性骨胶对甲醛吸附量与吸附时间、吸附温度之间的关系,初步应用一级、二级吸附动力学模型对其吸附曲线进行拟合,并对其吸附动力学特征和吸附机理进行了探讨。结果表明:当吸附温度为55℃、吸附时间为7 h时,新型改性骨胶对甲醛的吸附量(56.2 mg/g)最大;新型改性骨胶的吸附动力学曲线符合一级、二级吸附动力学模型,吸附过程包括物理吸附和化学吸附。     

Hydrogels as adsorbents of organosulphur compounds currently found in diesel

Hydrogels of chitosan were synthesised using glutaric dialdehyde as the crosslinking agent in an acetonitrile/water solution (1:4, v/v). These hydrogels recognised and adsorbed the dibenzothiophene sulfone (DBTS) against other related compounds found in diesel, e.g. dibenzothiophene (DBT), fluorene (FLE) and 4,6-dimethyl DBT (DMDBT). In order to improve the recognition and adsorption of DBTS, the latter compound served as a template for the building of recognition sites inside the hydrogel matrix through the use of the molecular imprinting technique (MIT). Despite the adsorption capacity of the molecular imprinted hydrogel (MIH) was not increased, the imprinting process of chitosan allowed both an enhancement of two orders of magnitude in ligand affinity constant and material homogeneity as seen by SEM. The change in swelling degree (Q) suggested the presence of a conformational memory of the hydrogel that might allow the design of stimuli-response but also tailored-made hydrogels responding at a required factor as temperature. The imprinting process improved ligand recognition and consequently hydrogel’s specificity as shown by a monolayer adsorption. In contrast, the adsorption isotherm of DBTS by the non-imprinted hydrogel showed a multilayer adsorption due to non-specific interactions.     

戊二酸在冰醋酸和环己酮、环己醇及五种混合溶剂中的溶解度的测定

By using the laser-monitoring technique, solid-liquid equilibrium data of glutaric acid in cyclohexanol, cyclohexanone, their five mixed solvents and acetic acid were measured within the temperature range from 292.15K to 354.60K by dynamic method. Empirical formula and λh equation were used to correlate the solubilities of glutaric acid in eight solvents. The maximal average relative deviations were 1.15% and 2.20% by using the empirical formula and λh equation to correlate the solubility data. The results showed that the empirical formula and λh model could correlate the solubility data of glutaric acid in eight solvents. In addition, the solubility data of glutaric acid in five mixtures （cyclohexanone＋cyclohexanol） could be predicted with the NRTL equation utilizing the parameters of the binary systems. The total average relative deviation was 3.60%. The results indicate that the NRTL equation could well predict the solubilities of glutaric acid in the mixed solvents of cyclohexanone and cyclohexanol.