标准加入-原子荧光光谱法测定罐头中的痕量锡

用微波消解处理样品,采用标准加入-原子荧光光谱法测定罐头中的锡.通过实验探讨了样品预处理条件、仪器条件、微波消解程序、还原剂浓度等对锡测定的影响.锡浓度(X)在1～100 μg/L范围内与荧光强度(Y)呈线性关系,线性方程为Y=50.15X+12.13,相关系数r=0.9995.用该法对水果和蔬菜罐头样品进行了测定,并...     

导数微分脉冲极谱法同时测定铅和锡

铅（Ⅱ）和锡（Ⅱ）在０．０１ｍｏｌ／Ｌ盐酸－０．１ｍｏｌ／Ｌ硫氰化钾介质中均有良好的微分脉冲极谱法,但波峰相互重叠,难以用常规的极谱分析法进行两组分同时测定。本文提出以导数法对铅和锡的重叠极谱波进行解析处理,较好地消除了背景电流的影响,并采用零交点法对铅和锡进行了同时测定,方法简便。该法还被应用于实验样品的分析,取得较好结果。     

氢化物无色散原子荧光法测定化探样品中的锡

建立了氢化物无色散原子荧光法测定化探样品中的锡元素的方法.在HNO3、HCl、HClO4作用下,于中温电热板加热至冒高氯酸的白烟,赶尽HNO3,趁热加入HCl将锡还原成低价;用硫脲-抗坏血酸消除铁等过度金属元素的干扰,以氢化物原子荧光法测定化探样品中的锡.研究了酸度、KBH4浓度、灯电流、还原剂等多种因素对测定结果的影响.经国家一级标准样品(GBW07401-8)验证,测定结果在允许范围以内.     

电感耦合等离子体质谱法测定食品中的锡

建立电感耦合等离子体质谱法测定食品中锡的方法。样品用浓硝酸冷消化后经微波消解,以纯水稀释定容消解液,选择分析目标物~(120)Sn、内标~(115)In上机测定。锡含量在0~50μg/L范围内与谱线强度线性良好,相关系数为0.999 8,检出限为0.018 mg/kg。对高、中、低3个浓度级别的样品溶液进行测定,测定结果的相对标准偏差分别为1.71%,2.42%,2.74%(n=6),样品加标回收率在98.5%~100.4%之间,该方法对实际样品的测定结果与国标法测定结果的相对偏差小于3.0%。该方法快速,干扰少,适合于食品中锡的测定。     

长缝石英管氢化物-火焰原子吸收光谱法测定化探样品及铅锭中微量锡

长缝石英管氢化物原子吸收法测定锡,具有较低的检出限,是一个方便、快速、灵敏的分析方法,特别适用于地质化探样品及铅锭的测定.通过对锡氢化物发生的酸度等条件进行了研究并提出克服干扰元素的办法.地质样品测定下限为0.5×10~(-6)g,铅锭样品测定下限为0.075×10~(-6)g.完全满足地质化探及铅锭测定的技术要求.     

改造的平面光栅直读光谱仪在测定化探样品中银硼锡元素的应用

平面光栅摄谱仪是地球化学普查样品中,测定银、硼、锡等元素常用的仪器.为提高分析效率和质量,2015年我单位将二米平面光栅摄谱仪改造为CCD-Ⅰ型平面光栅直读光谱仪.改造后的仪器检测限为Ag:0.013μg/g,Sn:0.43μg/g,B:0.71μg/g.精密度(RSD%,n=12)均小于10%,测定国家一级标准物质结果与标准值相符,完全满足地球化学普查样品中银、硼、锡等元素的分析要求.     

锡的快速示波极谱测定——Triton X-155的应用

钖的极谱测定方法很多,但都存在着线性范围狭窄的缺点。实验表明,在测定底液中加入一定量的非离子型表面活性剂TritonX-155能使线性范围变宽。用本方法对川西某地多金属矿样锡的分析,结果在0.00X—X.00％范围内均较满意。本方法具有简便、快速、测定范围宽的特点。 1.仪器及试剂: (1)仪器:成都仪器厂制造的JP-1A型示波极     

碱熔、分离沉淀—电感耦合等离子体质谱法快速测定地球化学样品中的锡

利用样品处理过程中,试液加入内标混匀后不需精确定容的特点,通过过滤分离沉淀、减少基体影响,采用硝酸酸化、避免氯离子干扰进行方法改进。样品经氢氧化钠熔融,热水提取,过滤分离沉淀,硝酸酸化后加入铑内标,粗略定容,电感耦合等离子体质谱仪测定,建立了一套快速、准确、批量测定地球化学样品中锡的方法。该方法经国家一级标准物质验证,分析结果与标准值吻合,相对标准偏差(RSD,n=6)落在4.8%~9.6%之间,方法检出限为锡:0.27μg/g。该方法操作简单、快速、易于掌握,线性范围宽,准确度和精密度均能满足地质找矿需要,已成功应用于本中心大批量地球化学样品锡元素的测定。     

电感耦合等离子体质谱法同时测定地质样品中镉、锗、钴

建立电感耦合等离子体质谱法同时测定地质样品中镉、锗、钴含量的分析方法。样品用氢氟酸-硝酸混合溶液加热溶解,然后加热浓缩驱酸,再用硝酸溶液(1+1)复溶提取,在选定的仪器工作条件下进行测定。镉、锗、钴的含量分别在0.00~0.10,0.00~5.00,0.00~50.00 μg/g范围内与质谱峰强度呈良好的线性关系,相关系数均大于0.999,方法检出限分别为0.01,0.02,0.02 μg/g。用该方法对国家一级标准物质进行测定,测定值的相对误差均小于10%,测定结果的相对标准偏差为0.79%~8.45%(n=12)。该方法样品处理过程简便,检测效率高,适用于批量地质样品中镉、锗、钴的测定。     

碱熔融-电感耦合等离子体原子发射光谱法测定氧化铟锡烧结混合粉中5种杂质元素

采用氢氧化钠熔融样品,热水浸取后盐酸酸化,建立了碱熔融-电感耦合等离子体原子发射光谱(ICP-AES)法测定氧化铟锡烧结混合粉中Fe、Ca、Mg、Al和Si等元素的分析方法.试验结果表明:称取0.500 0 g试样,加入0.80 g氢氧化钠,在灰化炉中熔融120 min,可将样品完全溶解.基体铟和锡的干扰采用基体匹配法消除,被测元素之间没有光谱干扰.钠盐对硅的测定有一定影响,可在标准溶液中加入一定量氢氧化钠予以消除.对方法进行精密度和加标回收试验,测得结果的相对标准偏差均小于5%,方法加标回收率在90%~105%之间.     

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。     

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.     

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.     

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.     

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.     

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.     

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^-。     

化学计量中不确定度评定研究进展

测量不确定度是表征合理地赋予被测量之值的分散性的参数。本文针对化学计量不确定度评定基础模型仅适用于线性模型、概率分布为正态分布或缩放位移t分布等局限,介绍了近年来不确定度评定的研究热点:蒙特卡罗方法(Monte Carlo Method,MCM),不确定度评定的来源、评定概念、评估方法及其发展过程,扩大了测量不确定度评定与表示的适用范围。