高效液相色谱法测定面粉中过氧化苯甲酰

由于过氧化苯甲酰具有使面粉增白、增筋及杀菌等效果 ,故面粉加工工艺中用其作为面粉改良剂。但有些面粉加工厂 ,为改善面粉的感官性状 ,以次充好 ,随意过量添加过氧化苯甲酰。而现在国内尚无测定面粉及其制品中过氧化苯甲酰的标准方法。本文对照文献 [1],试验了面粉中过氧化苯甲酰的高效液相色谱法。样品中过氧化苯甲酰用无水乙醇提取 ,用碘化钾将其还原为苯甲酸 ,ＯＤＳ Ｃ18柱分离 ,紫外检测器 2 30ｎｍ检测 ,以保留时间定性 ,峰面积定量。本法检出限为 1.0ｍｇ·Ｌ- 1,回收率大于86 5 % ,平均相对标准偏差 5 .2 % ,本法操作简便 ,能满…     

电感耦合等离子体发射光谱法检测镍基/钴基高温合金中硼磷硅

采用一定比例的混合酸溶解样品,利用基体匹配配制一系列标液消除基体的影响,以及轴向观测喷嘴吹扫技术来提高待测元素的灵敏度,使用电感耦合等离子体发射光谱(ICP-OES)测定镍基/钴基高温合金中硼磷硅。各元素选的分析线依次为B 182.577 nm、P 178.222 nm、Si 185.005 nm。检测范围分别是：B：0.001%-3.0%,P：0.003%-0.20%,Si：0.005%-3.0%,检出限范围是0.00005%-0.0004%,线性相关系数>0.9995。加标回收率为90.0%-105.0%,精密度RSD<2.0%。该方法操作简单快速,结果令人满意。     

离子色谱法测定磷酸氢钙中的氟化物

建立了离子色谱法测定磷酸氢钙中氟化物的方法。用本法测得的结果与化学法相符，相对标准偏差为0.65%-4.36%，回收率为99.5%-100.3%。     

低阶煤温和液化-炭化耦合转化过程及产物性质

基于低阶煤温和液化-炭化耦合工艺,主要研究了390-450℃液化温度条件下的产物分布特征,分析了所得液相产物和半焦的性质。结果表明,有机液相产率达23.44%-33.26%(干燥无灰基煤为基准),半焦产率达49.56%-68.72%(干燥无灰基煤为基准);所得液相产物水含量为1.30%-2.49%,不含固体颗粒,有机液相产物的正己烷可溶物含量达98.95%以上;所得半焦碳含量高达87.87%-93.45%(干燥无灰基),部分半焦产物具有强黏结性的特点,并且黏结性与其沥青质含量相关。     

电感耦合等离子体质谱法测定高纯镓中痕量杂质

采用电感耦合等离子体质谱（ICP-MS）测定高纯镓中痕量杂质元素,以Rh作为内标补偿校正镓基体的抑制效应,采用异丙醚萃取分离镓与ICP-MS技术联用,拓展分析方法应用范围,可满足99.9999%-99.99999%超高纯镓分析方法要求。方法检出限为0.006-0.062μg/L;加标回收率为86.8%-121.4%之间;RSD为1.1%-8.6%。     

快速溶剂萃取-凝胶渗透色谱净化-气相色谱-质谱法测定土壤中11种半挥发性有机物

建立了快速溶剂萃取–凝胶渗透色谱净化–气相色谱–质谱法测定土壤中11种半挥发性有机物的分析方法。取样量为10.0 g,萃取溶剂为丙酮–二氯甲烷(体积比为3∶7),使用凝胶渗透色谱净化,气相色谱–质谱仪进行测定。11种半挥发性有机物的质量分数在0.1-5 mg/kg的范围内,相对响应因子的相对标准偏差小于15%,方法的检出限为0.04-0.06 mg/kg,当加标量为0.25、0.5、1 mg/kg时,测定结果的相对标准偏差分别为4.8%-13.7%、3.8%-9.5%、3.4%-10.8%(n=6),加标回收率为55%-110%。该方法适用于土壤中11种半挥发性有机物的检测。     

高频燃烧红外吸收法测定氧化钴粉中的硫

采用高频红外吸收法测定了氧化钴粉中硫的含量,并对样品作测定前的预处理（物理处理）,在测定上选用复合型助熔剂,解决了高频感应炉中因顶吹氧气流的作用而导致的样品喷溅问题,并将镍作为辅助助熔剂应用于碳硫测定。该方法可准确测定硫含量为0.001%-0.1%的氧化钴粉中的硫,回收率为95.6%-104.8%。RSD为2.2%-4.9％。     

孔雀石绿分子印迹96孔检测板的制备及应用研究

为更加快速灵敏简单的检测水产品中的孔雀石绿残留,通过原位聚合法,以10%的乙腈甲苯溶液为溶剂,MAA为功能单体、EGDMA为交联剂(模板分子与之比例为1:4:20),制备分子了印迹聚合物。通过包被MIP到96孔板上研发了以化学发光法检测的MG-MIP-96孔检测板,其标准曲线为y=-29197.49x + 1945998.45,R2 = 0.9416,线性范围时30-66.64ng/ml。检测限为3.355ng/ml,批内变异系数范围为7.38%-18.07%,批内回收率范围为103.41%-144.45%。批间变异系数范围为12.45%-17.52%,批间回收率范围为100.07%-143.20%。以孔雀石绿结构类似物副品红(PA)和结晶紫(CV)进行特异性检测的交叉率分别为27.97%、30.97%。说明此新型检测方法具有很大的研究价值和实际应用价值。     

液相色谱-串联质谱研究面粉及其制品中偶氮甲酰胺降解规律及氨基脲污染水平

建立了面粉及其制品中氨基脲的液相色谱-串联质谱(LC-MS/MS)测定方法,并研究了面粉及其制品中偶氮甲酰胺降解规律及氨基脲污染水平。面粉及其制品等经0.1 mol/L HCl溶液水解,邻硝基苯甲醛衍生化,乙酸乙酯提取,正己烷脱脂后,采用LC-MS/MS测定,内标法定量。氨基脲的线性范围为0.5~100μg/L;在面粉、馒头、面包等基质中添加浓度为0.5,1.0,5.0μg/kg时,氨基脲回收率范围为89.0%~99.4%,相对标准偏差在4.8%~12%之间;氨基脲定量限为0.5μg/kg。面粉制品中氨基脲的含量与偶氮甲酰胺的添加量呈线性关系。市售面包中氨基脲的阳性检出率为92.0%,阳性样品中氨基脲污染水平为17.6~353.0μg/kg,表明目前我国面包制品中氨基脲污染状况较为严重。     

高效液相色谱法测定面粉及面粉制品中乙二胺四乙酸二钠的含量

在未使用离子对试剂和高盐缓冲液条件下,采用亲水性C_(18)反相液相色谱柱,以甲醇-水体系为流动相,建立了面粉及面粉制品中乙二胺四乙酸二钠含量的高效液相色谱测定方法。样品采用水溶液提取,在超声辅助下与三氯化铁反应生成稳定的衍生产物,用三氯甲烷净化衍生产物。采用高效液相色谱法以pH 4.0甲醇-水溶液(10∶90,体积比)为流动相,亲水性C_(18)反相液相色谱柱为固定相,260 nm波长下测定面粉及面粉制品中乙二胺四乙酸二钠含量。乙二胺四乙酸二钠的质量浓度在1.0~50.0 mg/L范围内呈良好的线性关系,其相关系数为0.999 6,检出限为3.0 mg/kg,定量下限为10.0 mg/kg。面粉样品添加浓度在10.0~200 mg/kg范围内,加标回收率为95.0%~103%,相对标准偏差为4.0%~6.3%,可满足面粉及面制品中乙二胺四乙酸二钠的快速检测和定量分析要求。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.