农产品中多种农药残留的气相色谱-质谱联用法测定

建立了同时检测大白菜、苹果、大豆和豆沙中211种农药残留的气相色谱-质谱联用法。农药经乙腈-水溶液匀质提取,C18固相萃取柱净化和PSA固相萃取柱净化,洗脱液浓缩后用丙酮-正己烷(1∶1)溶解,经HP-5MS石英毛细管柱分离后,用气相色谱-质谱联用仪采用选择离子扫描方式测定,外标法定量。结果表明211种农药在0.05~0.5 mg/L范围内线性关系良好,相关系数为0.975~0.998,其定量下限为0.002~0.020 mg/kg。在0.1 mg/kg加标水平下,211种农药在大白菜、苹果、大豆和豆沙中的平均回收率为67%~117%,相对标准偏差为1.1%~23.8%。该方法操作简单、净化效果好、灵敏度高,适用于蔬菜、水果等农产品中多种农药残留的测定。     

气相色谱-质谱法测定茶叶中23种农药残留量

采用气相色谱-质谱法测定茶叶中23种农药的残留量。茶叶样品以乙腈超声提取,以复合双层固相萃取柱净化。在气相色谱分离中用HP-5MS色谱柱为固定相,在质谱分析中采用多反应监测模式。以环氧七氯为内标物。方法的检出限(3S/N)在0.003~0.02mg·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87.5%~104%之间,测定值的相对标准偏差(n=6)在1.4%~9.9%之间。     

高效液相色谱-串联质谱法测定淡水养殖池塘水体及鱼虾体内的藻毒素

采用高效液相色谱-串联质谱法测定了淡水养殖池塘水体及鱼虾体内藻毒素MC-LR和MC-RR。水样经微孔滤膜过滤后,通过固相萃取柱富集净化。鱼、虾冻干后粉碎,以甲醇水溶液提取,提取液经固相萃取柱富集净化。采用UPLC BEH C18色谱柱(100×2.1mm,3.5μm),以0.1%甲酸水溶液和含0.1%甲酸乙腈溶液为流动相,质谱采用选择离子监测模式测量。结果表明,藻毒素的质量浓度在0.5~500μg·L~(-1)范围内时,峰面积与样品浓度呈良好线性关系。MC-LR和MC-RR的方法检出限分别为0.05μg·L~(-1)和0.08μg·L~(-1)。藻毒素在空白水样中的加标回收率为88.5%~98.5%,相对标准偏差为5.2%~8.3%;在鱼、虾组织中的加标回收率为63.8%~85.2%,相对标准偏差为6.7%~9.8%。实际测得某养殖池塘水中存在藻毒素污染,且部分水产品中检测到了MC-LR和MC-RR。     

超高效液相色谱-串联质谱法测定畜产品中6种青霉素类药物残留

采用超高效液相色谱-串联质谱法快速测定牛肉和牛奶中青霉素类药物残留。样品以磷酸盐缓冲溶液提取、乙酸锌沉淀蛋白、正己烷脱脂,然后经HLB固相萃取柱净化后,采用超高效液相色谱-串联质谱分离检测,外标法定量。6种青霉素的线性范围均在25.0μg·L-1以内,检出限(3S/N)为2μg·kg-1,测定下限(10S/N)为5μg·kg-1。加标回收率在77.0%~99.8%之间,测定值的相对标准偏差(n=6)在3.7%~13%之间。     

超高效液相色谱-串联质谱测定饲料中镇静剂类和β-受体激素类药物残留

采用超高效液相色谱-串联质谱技术,建立了饲料中8种镇静剂类和15种β-受体激素类药物残留的分析检测方法。样品采用乙腈-1%(体积分数)三氯乙酸水溶液(7∶3,v/v)提取,目标物通过阳离子固相萃取柱净化,经Agilent Zorbax Eclipse Plus C_(18)色谱柱(100 mm×3.0 mm,1.8μm)分离,液相色谱-串联质谱进行检测,标准曲线内标法定量。结果表明:23种目标物在2.0~200.0μg/L内线性关系良好(r20.99)。在饲料样品基质中,目标化合物在5.0、10、50μg/kg 3个加标水平下的平均回收率为75.1%~102.4%,相对标准偏差(RSD)为4.3%~14.3%(n=6)。该方法净化效率高,适用范围广,可用于饲料中镇静剂类和β-受体激素类药物残留筛查和检测。     

超高效液相色谱法快速测定贝类中的软骨藻酸残留北大核心CSCD

利用超高效液相色谱快速测定贝类中的软骨藻酸残留。样品经甲醇(1+1)溶液提取,采用Oasis MAX固相萃取柱对提取液进行净化后,在Waters ACQUITY UPLC BEH C18色谱柱上分离,以乙腈-0.1%(体积分数)三氟乙酸(13+87)混合液为流动相进行洗脱,紫外检测波长为242nm。软骨藻酸的线性范围为0.1~10.0mg·L-1,测定下限(10S/N)为0.2mg·kg-1。加标回收率在76.8%~91.2%之间,测定值的相对标准偏差(n=6)在11%~16%之间。     

固相萃取/超高效液相色谱法测定纺织品中14种紫外吸收剂

建立了固相萃取(SPE)净化,超高效液相色谱(UPLC)同时测定纺织品中14种二苯甲酮类(BPs)和苯并三唑类(BZTs)紫外吸收剂的分析方法。样品以甲醇-四氢呋喃超声提取,提取液经ENVI-Carb固相萃取柱净化后,在C18色谱柱和乙腈-0.1%甲酸水流动相下梯度洗脱分离,二极管阵列检测器测定。结果表明,14种紫外吸收剂在0.1~50 mg/L浓度范围内线性关系良好,相关系数均大于0.999;方法检出限为1~5mg/kg;阴性涤纶和腈纶样品在3个加标水平下的平均回收率(n=6)为81.5%~99.1%,相对标准偏差(RSD)为2.8%~7.5%。该方法简单快速,回收率和精密度良好,适用于纺织品中14种紫外吸收剂的同时测定。     

超高效液相色谱法快速测定贝类中的软骨藻酸残留

利用超高效液相色谱快速测定贝类中的软骨藻酸残留。样品经甲醇(1+1)溶液提取,采用Oasis MAX固相萃取柱对提取液进行净化后,在Waters ACQUITY UPLC BEH C18色谱柱上分离,以乙腈-0.1%(体积分数)三氟乙酸(13+87)混合液为流动相进行洗脱,紫外检测波长为242nm。软骨藻酸的线性范围为0.1~10.0mg·L-1,测定下限(10S/N)为0.2mg·kg-1。加标回收率在76.8%~91.2%之间,测定值的相对标准偏差(n=6)在11%~16%之间。     

凝胶渗透色谱-固相萃取净化-超快速液相色谱-串联质谱法检测牛肉中9种类固醇激素残留

建立了凝胶渗透色谱分离-固相萃取净化-超快速液相色谱-串联质谱 (GPC-SPE-RRLC-MS/MS)测定牛肉中群勃龙、勃地龙、诺龙、睾酮、美雄酮、甲基睾酮、司坦唑醇、黄体酮、苯丙酸诺龙9种类固醇激素残留的方法.试样经β-盐酸葡萄糖醛苷酶/芳基硫酸酯酶酶解,叔丁基甲醚超声提取,凝胶渗透色谱和HLB固相萃取柱净化,以乙腈-0.1%甲酸水溶液为流动相,经Agilent Plus C18柱分离后以MS/MS多反应监测扫描模式检测.方法线性相关系数r＞0.999,定量限为0.2～0.7 μg/kg.在3种浓度添加水平0.3, 1.0, 4.0 μg/kg下,其平均回收率为81.4%～110%;相对标准偏差(RSD)为2.2%～9.8%.本方法已成功应用于高脂肪和基质复杂样品中9种类固醇激素残留的检测.     

果实类中药材中20种有机磷农药残留量的同时测定

建立了果实类中药材中多种有机磷农药残留同时测定的方法,并对影响提取、净化、检测效率的因素进行优化。样品用乙酸乙酯提取,凝胶渗透色谱收集9~15 min流分,ENVI-Carb固相萃取柱净化,DB-1701毛细管色谱柱分离,火焰光度检测器检测,外标法定量。在优化条件下,20种有机磷农药在0.01~2.0mg/L范围内具有良好的线性关系,相关系数为0.996 6~0.999 5,检出限(S/N=3)为0.66~5.78μg/kg。3个加标水平下的平均回收率为80.2%~109.9%,相对标准偏差为2.3%~13%。该方法操作简便、准确、净化效果好,可满足果实类中药材中多种有机磷农药残留的同时测定要求。     

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.     

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。     

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)。     

Stages of thermal decomposition of sodium oxo-salts of sulphur

Thermal behaviour of sodium oxo-salts of sulphur: Na₂SO₄, Na₂S₂O₇, Na₂S₂O₆, Na₂SO₃, Na₂S₂O₅, Na₂S₂O₄, Na₂S₂O₃, Na₂S₃O₆ and of sulphides Na₂S and Na₂S₂ was studied on heating up to 1000°C. The experiments were performed with anhydrous compounds obtained from commercial products by recrystallisation and dehydration. The stage mechanisms of decomposition of anionic sub-lattices of the salts have been proposed basing on the Górski’s morphological classification of simple species. The thermal stability and the stage decomposition mechanisms were correlated with the structure and the potential chemical properties of the salt anions. The thermal decomposition processes were studied by means of thermal analysis, and the decomposition products were identified by means of X-ray phase analysis.     

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.