浊点萃取-石墨炉原子吸收光谱法测定膨化食品中铅

以8-羟基喹啉(8-HQ)为螯合剂,在pH 9缓冲溶液中,痕量铅(Ⅱ)与8-HQ生成螯合物,加入表面活性剂Triton X-100用浊点萃取分离富集样品中痕量铅。分取部分表面活性剂相用0.1mol·L-1硝酸溶液定容至2mL,所得溶液直接用石墨炉原子吸收光谱法进行测定。对影响浊点萃取的因素和共存离子的干扰等进行了试验并予以优化。方法的检出限(3σ)为0.85pg。应用所提出的方法测定了膨化食品样品中铅的含量,在5种样品中用标准加入法进行方法的回收试验,测得回收率在91.7%～101.7%之间。     

浊点萃取富集-火焰原子吸收光谱法测定水样中痕量锌

以1-(2-吡啶偶氮)-2-萘酚(PAN)为络合剂,在pH 7.0磷酸盐缓冲溶液中,痕量锌(Ⅱ)与PAN生成络合物,加入非离子表面活性剂OP-8用浊点萃取分离富集水样中痕量锌。分取部分表面活性剂相用盐酸溶解,所得溶液直接用火焰原子吸收光谱法进行测定。对影响浊点萃取的因素和共存离子的干扰等进行了试验并予以优化。方法的检出限(3σ)为2.4μg.L-1。应用所提出的方法测定了水样中锌的含量,并用标准加入法进行方法的回收试验,测得回收率在95.0%~103.6%之间。     

浊点萃取-火焰原子吸收光谱法测定样品中的痕量钴

研究了基于表面活性剂Triton X-114和络合剂吡咯烷二硫代氨基甲酸铵（APDC）浊点萃取钴的样品前处理方法.优化了浊点萃取条件参数,包括pH值、Triton X-114用量、APDC浓度、平衡温度及时间等,建立了浊点萃取-火焰原子吸收光谱法测定痕量钴的方法.该法的检测限（3σ）为2.6μg/L,相对标准偏差RSD为6.2%（n=7,c=200μg/L）.该法成功地应用于海带、维生素B12注射液等样品中钴的测定.     

浊点萃取-分光光度法测定自来水及酒类样品中的痕量铁

利用非离子表面活性剂TritonX-100在温度高于其浊点时形成相分离行为,建立了浊点萃取-分光光度法测定痕量铁的新方法,探讨优化了以KSCN为显色剂,TritonX-100浊点萃取富集痕量铁的实验条件.研究发现:加入正辛醇可使TritonX-100的浊点降低约30℃,有利于萃取实验的进行;同时,加入的正辛醇与TritonX-100对痕量铁起到了协同萃取作用.在优化了的实验条件下,进行了痕量铁的分析,检出限为0.02mg·L-1,加标回收率为97.4%～101.6%,应用于自来水及酒类样品中痕量铁的测定,结果满意.     

浊点萃取-激光热透镜光谱法测定痕量钯

以2-(5-溴-2-吡啶偶氮)-5-二甲氨基苯胺(5-Br-PADMA)为络合剂,用非离子型表面活性剂Triton X-114浊点萃取样品溶液中的痕量钯。探讨了溶液p H、络合剂用量、平衡温度及时间、表面活性剂用量等实验条件对体系浊点萃取效率及测定灵敏度的影响,并详细研究了多种阴、阳离子对测定的干扰情况。在最佳条件下,钯浓度在4~80 ng·m L-1范围内与热透镜信号强度呈线性关系,方法的检出限为1.2 ng·m L-1,该法用于自来水中痕量钯的测定,加标回收率为95.5~96.7%,相对标准偏差为0.87%~2.49%。     

浊点萃取预富集火焰原子吸收光谱法测定水样中痕量镍

以1-(2-吡啶偶氮)-2-萘酚为络合剂,在pH 7.0,用Triton X-100非离子表面活性剂浊点萃取水样中痕量镍.表面活性剂相用硝酸-甲醇(1 9)混合液0.5 mL分散,所得溶液直接引入仪器进行火焰原子吸收测定,方法的检出限(3σ)为3.77×10-3mg·L-1,应用所提出方法测定了河水样品,测定结果的相对标准偏差(n=6)为2.98%.     

浊点萃取-火焰原子吸收光谱法测定菠菜中镁、锌和铜

在pH 8.0缓冲溶液中,以8-羟基喹啉为螯合剂,镁、锌和铜均与8-羟基喹啉生成螯合物,加入Triton X-100表面活性剂用浊点萃取分离富集菠菜样品中镁、锌和铜。分取部分表面活性剂相用乙醇定容至25mL,所得溶液直接用火焰原子吸收光谱法进行测定。对影响浊点萃取的因素和共存离子的干扰等进行了试验并予以优化。镁、锌和铜的检出限(3s/k)依次为0.057,0.064,0.032mg.L-1。应用此法测定了大叶菠菜和小叶菠菜中3种元素的含量,在两种样品中用标准加入法进行方法的回收试验,测得镁的回收率在93.3%～100.5%之间;锌的回收率在91.7%～97.9%之间;铜的回收率在94.0%～107.1%之间。     

浊点萃取-热喷雾火焰炉原子吸收光谱法测定水中痕量锌(Ⅱ)

建立了以吡咯烷二硫代氨基甲酸铵(APDC)为络合剂、TritonX-100为表面活性剂的浊点萃取-热喷雾火焰原子吸收光谱法测定水样中痕量锌的方法.考查了APDC的浓度、溶液酸度、表面活性剂浓度、加热时间、水浴温度、干扰离子等实验条件对浊点萃取效率的影响.在最优化的实验条件下.方法的检出限为0.1 ng/mL,RsD为4...     

人血白蛋白制品中超痕量铝的测定

建立了浊点萃取石墨炉原子吸收光谱法测定人血白蛋白样品中超痕量铝的新方法。探讨了溶液酸度、络合剂的种类及浓度、非离子表面活性剂的浓度、平衡时间及温度等因素对浊点萃取过程的影响。以1-(2-吡啶偶氮)-2-萘酚为络合剂,Triton X-114为非离子表面活性剂,浊点萃取分离富集10mL样品溶液,Al(Ⅲ)的富集倍数为34.8,在最佳工作条件下,铝的检出限为0.06μg/L;样品测定的相对标准偏差(n=7)为3.6%,加标回收率95.6%~98.4%。方法适合人血白蛋白样品中超痕量铝的分析测定。     

超声辅助浊点萃取-原子荧光光谱法测定水中痕量汞

为了适应水中痕量汞的分析要求,降低汞的检出限,建立了一种超声辅助浊点萃取预富集联合原子荧光光谱法测定水样中痕量汞的方法。该方法采用硫代米氏酮为络合剂,以非离子型表面活性剂Triton X-114为萃取剂,将水样中的痕量汞富集于表面活性剂相。在原子荧光光谱分析前,加入磷酸三丁酯作为消泡剂,用5%盐酸溶液定容,富集倍数可以达到10倍。优化萃取体系pH、络合剂用量、萃取剂用量、超声平衡条件等浊点萃取的条件,在最优条件下,该方法检出限为0.003 μg/L,相对标准偏差为4.2%~8.6%,加标回收率为85%~106%。结果表明,超声辅助浊点萃取-原子荧光法能够适用于对地表水、自来水等清洁水样中痕量汞的分析,且具有更低的检出限,良好的准确度和精密度,能够适应于更高的样品分析要求。     

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.     

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。     

Synthesis of phenolic components of Grains of Paradise

Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.     

Study of hydration of two cements of different strengths

Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, M_o, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700^oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.     

Acid hydrolysis of carboxymethylcellulose of low degree of substitution

Cotton cellulose was swollen in a sodium hydroxide solution and carboxymethylated by a two-bath method for different periods of time for each process. The kinetics of acid hydrolysis and the crystallinity of the swollen and carboxymethylated samples were measured. The proportion of broken bonds, rate constants for hydrolysis, and permeability of cellulose to hydrolyzing agents were calculated. The susceptibility of glycosidic linkages to acid hydrolysis was improved by carboxymethylation more than by swelling in alkali. The increased accessibility of carboxymethylcellulose to acid was regarded as a consequence of increased intra-and intercrystalline swelling and of the glycosidic bonds' weakness caused by the electron-attracting carboxymethyl group on the C-6 position.     

氯氧化镁生成热的研究

用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。     

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.

     

Estimation of Kinetic Parameters of Thermal Oxidation of Ilmenite

The aim of the presented work was the investigation of thermal oxidation of ilmenite in static air atmosphere. The investigations were carried out by use of a derivatograph (MOM, Hungary). The changes of crystallographic structure of investigated samples were identified by X-ray diffractometry on Philips PW-1710 diffractometer. In temperature above 500°C appears structure of hematite Fe₂O₃. On the basis of the thermogravimetric measurements, the contracting area and contracting volume models were found as the best fitting experimental data. This revised version was published online in August 2006 with corrections to the Cover Date.     

Mechanism of action of base-catalyzed oxygenation of phenol derivatives

Cyclopropyl derivative of 2,6-di-tert-butylphenol is synthesized as a probe to investigate the mechanism of base-catalyzed autooxidation of phenol derivatives. Our study indicates that one electron reduction of molecular oxygen from phenolate gives phenoxyl radical 3, a key intermediate of autooxidation. The coupling of phenoxyl radical and superoxide radical gives peroxylate anion 4 and produces the final epoxy alcohol adduct 6.