气相色谱-串联质谱法测定烟草中97种农药残留量

利用气相色谱-串联质谱法(GC-MS/MS)检测烟草中97种农药残留。样品以乙腈为溶剂经加速溶剂萃取(ASE),提取液用Carbon-NH2固相萃取小柱净化后,采用VF-5MS色谱柱分离,用电子轰击离子源-多反应监测模式(EI-MRM)检测。97种农药的质量浓度在20~1 000μg·L-1范围内与其峰面积呈线性关系,方法的测定下限(10S/N)在0.02~22.4μg·kg-1之间;在50,100,500μg·kg-1的加标水平下,测得回收率在67.4%~116%之间,测定值的相对标准偏差(n=6)在1.9%~14%之间。     

固相萃取-在线凝胶渗透色谱-气相色谱-质谱法测定豆芽中53种农药残留量

采用固相萃取-在线凝胶渗透色谱-气相色谱-质谱法测定豆芽中53种农药残留量。豆芽样品以乙酸-乙腈(1+99)混合液提取,固相萃取小柱净化,采用在线凝胶渗透色谱-气相色谱分离,在质谱分析中采用选择离子监测模式。53种农药的质量浓度均在0.01~1.0mg·L-1范围内与其峰面积呈线性关系,方法的检出限在0.1~6.0μg·kg-1之间。在20,50,100μg·kg-1等3个浓度水平进行加标回收试验,回收率在72.3%~104%之间,测定值的相对标准偏差(n=6)在1.6%~6.6%之间。     

加速溶剂萃取-气相色谱-串联质谱法测定党参中69种农药残留量

采用加速溶剂萃取-气相色谱-串联质谱法测定党参中69种农药残留量。样品以乙腈为溶剂经加速溶剂提取,提取液用Carb/NH2固相萃取小柱净化。在气相色谱分离中用VF-5MS柱为固定相,在质谱分析中采用多反应监测模式。69种农药在一定的质量浓度范围内与其峰面积呈线性关系,方法的测定下限(10S/N)在0.03~21.2μg·kg-1之间。在20,100,200μg·kg-1等3个浓度水平进行加标回收试验,回收率在63.8%~110%之间,测定值的相对标准偏差(n=6)在1.9%~13%之间。     

超高效液相色谱法测定脐橙中橘红2号和苏丹红

采用超高效液相色谱法同时测定脐橙中的橘红2号和苏丹红染料。样品经乙腈超声提取,氨基固相萃取小柱净化后,用Waters ACQUITY UPLC BEH C18色谱柱分离,以乙腈-水为流动相进行梯度洗脱,采用二极管阵列检测器检测,检测波长分别为478 nm和515 nm。5种染料的质量浓度在0.20~20 mg·L-1范围内呈线性,检出限(3S/N)在0.31~0.53μg·kg-1之间。加标回收率在87.8%~99.4%之间,测定值的相对标准偏差(n=5)在0.54%~3.1%之间。     

气相色谱法测定食品中仲丁灵残留量

提出了气相色谱法测定食品中仲丁灵残留量的方法。样品用正己烷-丙酮(1+1)混合液提取,提取液经凝胶渗透色谱和固相萃取净化。用DB-1701色谱柱分离,电子捕获检测器测定。仲丁灵的质量浓度在10.0~500μg·L-1范围内与其峰面积呈线性关系,检出限(3S/N)为1.4μg·kg-1。添加10,20,50μg·kg-1 3个浓度水平进行加标回收试验,回收率在84.2%~97.2%之间,测定值的相对标准偏差(n=8)在3.8%~15%之间。     

大体积固相萃取-气相色谱法测定海水中10种多氯联苯

采用大体积固相萃取-气相色谱法测定海水中10种多氯联苯的含量。海水样品采用大体积样品采样器与聚苯乙烯/二乙烯基苯固相萃取柱进行萃取。萃取流量为5.0mL·min-1,丙酮作为洗脱剂。用Agilent HP-5石英毛细管色谱柱(30m×0.32mm,0.25μm)分离,微池电子捕获检测器检测。10种多氯联苯的质量浓度均在10.0μg·L-1以内与其峰面积呈线性关系,方法的检出限(3S/N)在0.002 3~0.012μg·L-1之间。测定值的相对标准偏差(n=7)在0.9%~1.3%之间,在0.5,1.5,4.0μg·L-1等3个浓度水平进行加标回收试验,回收率在80.7%~127%之间。     

分子印迹-固相萃取-高效液相色谱法测定鱼肉中的孔雀石绿

以本体聚合法制备孔雀石绿(MG)分子印迹聚合物,并以此为填料,制作针对孔雀石绿的分子印迹固相萃取小柱。鱼肉样品经乙腈超声提取,提取液过分子印迹固相萃取小柱,用甲醇-乙酸(9+1)混合液洗脱,洗脱液采用Eclipse Plus C18色谱柱分离,以50mmol·L-1乙酸盐缓冲溶液-乙腈(4+6)混合液为流动相进行洗脱,检测波长为620nm。孔雀石绿的线性范围为1.00~50.0μg·L-1,检出限(3S/N)为0.62μg·kg-1。对空白鱼肉样品进行加标回收试验,回收率在86.6%~95.4%之间,测定值的相对标准偏差(n=5)在3.6%~6.8%之间。     

快速溶剂萃取-气相色谱-质谱法测定土壤中24种半挥发性有机物含量

采用快速溶剂萃取-气相色谱-质谱法测定土壤中24种半挥发性有机物的含量。土壤样品以正己烷-乙酸乙酯(5+1)混合液进行萃取,所得萃取物用弗罗里硅土固相萃取小柱净化。在气相色谱分离中用DB-5MS色谱柱为固定相,在质谱分析中采用选择离子监测模式。24种半挥发性有机物在一定的质量浓度范围内与其峰面积呈线性关系,方法的检出限在0.83~4.48μg·kg~(-1)之间,测定下限在3.32~15.8μg·kg~(-1)之间。以空白样品为基体进行加标回收试验,所得回收率在60.4%~123%之间。测定值的相对标准偏差(n=4)在5.2%~19%之间。     

气相色谱-串联质谱法测定白酒中16种增塑剂

采用气相色谱-串联质谱法测定白酒中16种增塑剂的含量。样品经30℃水浴真空旋转蒸发10min去除乙醇后,用正己烷萃取,漩涡振荡1min,取上层有机相用TR-5MS色谱柱分离,选择反应监测扫描(SRM)模式测定。16种增塑剂的质量浓度在5~1 000μg·L-1范围内与其峰面积呈线性关系,检出限(3S/N)在5~15μg·kg-1之间。在50,100,500μg·kg-1等3个浓度水平进行加标回收试验,回收率在70.5%~120%之间,相对标准偏差(n=6)小于15%。     

高效液相色谱-串联质谱法测定生鲜乳中三聚氰胺的含量

采用高效液相色谱-串联质谱法测定生鲜乳中三聚氰胺残留量。样品经乙腈溶液超声提取,过Waters Oasis MCX固相萃取小柱净化,50℃氮气吹干,再用1.0mL乙腈溶解后供高效液相色谱-串联质谱分析。以Waters Hilic色谱柱(100 mm×2.1 mm,3μm)为固定相,用乙腈-5mmol·L-1乙酸铵(95+5)溶液洗脱,采用电喷雾正离子模式多反应监测,内标法定量。三聚氰胺的质量浓度在10.0μg·L-1以内呈线性,检出限(3S/N)为0.5μg·kg-1。取空白样品在3个标准加入水平下进行回收和精密度试验,回收率在99.8%~103%之间,测定值的相对标准偏差(n=10)在1.9%~3.2%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.     

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^-。     

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.     

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.     

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.

     

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。     

微量钙的测定方法研究进展

介绍了1995-2006年期间测定微量和痕量钙的方法,如电感耦合等离子体-原子发射光谱法、原子吸收光谱法以及离子色谱法等的工作原理和特点,并说明了其测定微量钙的应用领域。并对微量钙的测定技术进行了展望(引用文献55篇)。