微波灰化-电感耦合等离子体发射光谱法测定婴幼儿乳粉中的钙和磷

采用微波灰化-电感耦合等离子体发射光谱法（ICP-OES）测定婴幼儿乳粉中钙、磷元素含量.采用微波灰化法对婴幼儿乳粉进行前处理,正交试验方法确定微波灰化最佳条件,灰化后产物用2 mL硝酸溶液(体积比为1∶1)溶解后,用ICP-OES对钙、磷元素进行含量检测.磷加标回收率为86%～104%,钙加标回收率为87%～96%.磷的相对标准偏差为2.5%～7.0%,钙的相对标准偏差为3.9%～10.0%,能够满足日常检测要求.采用微波灰化法对婴幼儿乳粉中钙、磷元素进行样品前处理,相比微波消解方法,具有用时短、用酸量少、消解效果好、不需要进行赶酸处理等优点.与干法灰化和湿法消解相比大大减少了样品处理时间.采用微波灰化与ICP-OES结合对婴幼儿乳粉中的重要指标元素进行检测,在婴幼儿乳粉质量控制中有很好的应用价值.     

超高效液相色谱-串联质谱法同时测定水产品中9种有机磷农药残留量

采用超高效液相色谱-串联质谱法同时测定水产品中吡菌磷、伏杀硫磷、乙硫磷、甲基嘧啶磷、速灭磷、杀扑磷、亚胺硫磷、二嗪磷、治螟磷等9种有机磷农药残留量。水产品样品用冰乙酸-乙腈(1+99)混合液提取,加入乙二胺-N-丙基硅烷(PSA)吸附剂净化,所得样液用超高效液相色谱分离,电喷雾串联四极杆质谱进行检测。9种有机磷农药的质量浓度均在18μg.L-1以内与峰面积呈线性关系,方法的检出限(3S/N)为0.005mg.kg-1。以水产品样品为基体进行回收试验,方法的回收率在87.5%～102%之间,相对标准偏差(n=10)在3.7%～13%之间。     

吸光光度法测定水中总磷的改进

磷是生物体生长的必需的营养元素 ,主要以磷酸盐形式存在。水中的磷存在于溶液和悬浮物中 ,通过测定磷酸盐的含量可以估计水体是否受污染及污染的程度[1] 。总磷是自来水检测中一项重要指标。国标方法中采用中等强度还原剂抗坏血酸 ,可使稳定性提高 ,但灵敏度下降[2 ] 。本法检测的部分水样总磷含量较低 ,为提高灵敏度 ,用提高实验技术来弥补氯化亚锡甘油显色不稳定的缺点。采用过二硫酸钾为氧化剂 ,高压蒸汽消化法 ,将磷全部转化为正磷酸盐 ,酸性条件下 ,与钼酸铵反应 ,氯化亚锡甘油为还原剂用吸光光度法进行测定。改进国标法对色度、浊度…     

蜂蜜中多种有机磷农药残留量的气相色谱测定

介绍了应用配有FPD检测器的气相色谱仪测定蜂蜜中多种有机磷农药残留量的新方法。试样加水稀释,加入少量氯化钠,再用乙酸乙酯提取。以GC-FPD测定,外标法定量,必要时结果用不同极性的毛细管柱验证分析结果。敌百虫、皮蝇磷、毒死蜱、马拉硫磷和蝇毒磷分别在一定范围内,质量浓度与峰面积呈良好的线性关系。方法准确,重现性、精密度好,杂质干扰少。方法的检出限均为0.01mg.kg-1。     

基于三唑磷残留限量值的多检测线免疫试纸条的制备与应用

建立了基于三唑磷残留限量值(MRL)的免疫层析检测方法,可裸眼观察判断谷物、蔬菜和水果中的三唑磷农药残留水平。以粒径20 nm的胶体金标记三唑磷单克隆抗体于金标垫上,包被不同浓度的三唑磷包被原(检测线T1、T2、T3线)、羊抗小鼠Ig G抗体(质控线C线)于硝酸纤维素(NC膜)上,与吸水垫及PVC底板组合成层析试纸条。以大米、甘蓝和苹果为对象,优化了样品前处理方法、提取试剂等条件。结果表明,基于1/10三唑磷MRL值的试纸条(I)对三唑磷的裸眼观察检测灵敏度可达0.005、0.01和0.02μg/m L,优化调整后获得试纸条Ⅱ灵敏度设定为国标GB2763中的三唑磷MRL值依次为0.05、0.1和0.2μg/m L,并与3条检测线一一对应。结合前处理方法优化结果,样品经乙腈提取后,用PBS稀释10倍或者等体积溶剂置换后检测,此两种试纸条在8~12 min内均可准确判定农产品中三唑磷的残留是否超过MRL值,同时多区间定量范围的设定亦可较为准确地定量其残留值,结果与GC方法一致。本研究采用基于MRL值的3条检测线,对检测结果的判定更为直接、准确,无需换算,为基于MRL农产品安全性的快速判断提供了更为直观、简单、准确的方法。     

毛细管气相色谱法测定蔬菜中残留硫线磷

在气相色谱法测定蔬菜中残留硫线磷中提出了应用石英毛细管色谱柱(DB1701,30 m ×0．32 mm×0．25μm)分离并采用火焰光度检测,取一定量经粉碎的蔬菜试样,用乙腈萃取其中的硫线磷,分取萃取液一份,经氮气吹干后,用丙酮溶解其残渣进行气相色谱测定。方法的检出限为0．01 mg·kg-1,对不同的硫线磷浓度水平下进行精密度试验,测得RSD值在2．55％-11．80％间,用标准加入法测得方法的回收率在84．8％-102．0%间。     

多谱拟合(MSF)电感耦合等离子体发射光谱法测定钼精矿中磷

受钼精矿基体中铜、钼元素的干扰,ICP-OES法无法直接用于磷(213.617nm)的检测。本文考察了钼和铜谱线对磷(213.617nm)测定的影响,应用ICP-OES 多谱拟合(MSF)法消除铜(213.599nm)、钼(213.606nm)的光谱干扰,建立了适合钼精矿中磷的检测方法。对方法的准确度和精密度进行试验,钼精矿中磷的加标回收率为96.2%~103.7%,RSD为2.60%~6.02%。试验证明,本方法是一种较为理想的分析方法,适合钼精矿中磷的测量范围为0.0010%~1%。     

化学镀镍磷合金镀层孔隙率的电化学评价

本文通过研究镍磷合金、镍磷合金镀层和碳钢在不同浓度硝酸溶液中的动电位极化曲线 ,选择了能够快速检测镍磷合金镀层孔隙率的硝酸浓度 ,并对不同厚度的镍磷合金镀层试样进行评价 .结果表明 :镍磷合金镀层在 1 0 %硝酸溶液中的动电位极化曲线能准确地反映镀层的孔隙率 ,该硝酸溶液最适合作为应用电化学方法检测镀层孔隙率的检测溶液 ,其变化规律是随着镀层孔隙率的减少 ,镀层的腐蚀电位逐渐正移 .应用常规的孔隙率检测方法只能检测较大的孔隙 .     

离子液体作为流动相添加剂的亲水作用色谱-间接紫外检测法分析四丁基磷与四丁基铵

发展了用咪唑离子液体作为流动相添加剂的亲水作用色谱-间接紫外检测四丁基磷和四丁基铵的分析方法。研究了咪唑离子液体、吡啶离子液体作为流动相添加剂对四丁基磷和四丁基铵分析的影响,考察了咪唑离子液体的浓度、有机溶剂含量、检测波长等因素的影响,并讨论了离子液体的作用。采用亲水作用色谱柱,以乙腈-1.0 mmol/L 1-乙基-3-甲基咪唑四氟硼酸盐(体积比60∶40)为流动相,在色谱柱温度30℃,流速1.0 mL/min,紫外检测波长210 nm条件下,四丁基磷和四丁基铵离子在15 min内得到完全分离。检出限为1.0～1.2 mg/L,线性和重现性良好。将此方法应用于松花江水样品和克音河水样品的分析,加标回收率为95.9%～107%。该方法简单,易于应用。     

人工神经网络及模拟退火算法应用于原子吸收光谱法同时测定钙、磷

试验发现:原子吸收光谱法(AAS)在442.7 Nm波长处测定钙时受到大于0.10 mg·L-1磷共存的干扰,使钙的测定结果偏低,而且此负偏差降低的幅度随磷浓度的增加而增大.试验还发现:当共存磷的量在0.1～6.0 mg·L-1之间时,钙测量值的负偏差幅度与磷浓度之间存在明显的相关性.应用反向传播人工神经网络(BP-ANN)及模拟退火两种计算法对上述非线性干扰效应进行了研究,并提出了在单一波长检测的条件下,钙、磷两元素的原子吸收光谱法同时测定,此法应用于循环水中钙、磷的同时测定.两元素的检测范围依次为0.08～10.0 mg·L-1及0.10～6.0 mg·L-1,测得其回收率分别为100.5%和98.0%.     

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%.     

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.     

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.     

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.     

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.     

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.     

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.