液液萃取分离-气相色谱-串联质谱法同时测定水中12种有机氯农药

采用液液萃取分离-气相色谱-串联质谱法同时测定水中12种有机氯农药的含量。样品经正己烷提取,在气相色谱分离中用DB-5MS色谱柱为固定相,在质谱分析中采用多反应监测模式。12种有机氯农药在一定的质量浓度范围内与其峰面积呈线性关系,方法的检出限在0.002~0.032μg·L~(-1)之间,测定下限在0.008~0.128μg·L~(-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99.1%~126%之间,测定值的相对标准偏差(n=7)在2.3%~9.3%之间。     

QuEChERS法结合气相色谱-质谱法同时测定葡萄酒中16种农药残留

采用气相色谱-质谱法(GC-MS)测定葡萄酒中有机磷类及有机氯类等16种农药残留。样品经酸化乙腈提取后,提取液采用QuEChERS前处理法,经N-丙基乙二胺-石墨化碳黑-C18粉末净化。净化液采用Agilent HP-5MS色谱柱分离,质谱中采用电子轰击离子源-选择离子监测模式。16种农药的线性范围为0.05~2.00mg·L-1,方法的检出限(3S/N)在0.006~0.060mg·kg-1之间。对空白样品进行加标回收试验,回收率在87.6%~105%之间,测定值的相对标准偏差(n=6)在0.77%~6.9%之间。方法可以用于葡萄酒中农药残留的进出口检测。     

超声提取-气相色谱法测定鱼腥草中有机氯农药残留

提出了超声提取-气相色谱法测定鱼腥草中有机氯农药残留方法。采用丙酮-石油醚(1+1)混合溶剂超声提取30 min,然后浓硫酸净化、旋转蒸发浓缩,最后用气相色谱-电子捕获检测器(ECD)进行检测。有机氯农药的线性范围在0.001~0.20 mg·L-1之间,方法的检出限(3S/N)为0.023~0.29μg·kg-1,加标回收率在73.0%~115%之间,相对标准偏差(n=5)在1.4%~14%之间。本法与药典法对比,其回收率较高,适用于鱼腥草中有机氯农药的检测。     

气相色谱-双柱双电子捕获检测器测定鱼肉中的有机氯农药

采用气相色谱-双柱双电子捕获检测器(ECD)测定鱼肉样品中的10种有机氯农药(六氯苯、α-六六六、β-六六六、γ-六六六、δ-六六六、七氯、p,p′-DDE、o,p′-DDT、p,p′-DDD和p,p′-DDT)。样品经正己烷振荡提取后,提取液经自制酸性硅胶柱净化,采用DB-35MS和DB-5毛细管色谱柱进行双柱双ECD分析。10种有机氯农药的线性范围均为5.0~250μg·L~(-1),检出限(3.143s)在0.2~1.2μg·kg~(-1)之间。加标回收率在85.7%~121%之间,测定值的相对标准偏差(n=6)不大于16%。     

悬浮固化-分散液液微萃取-气相色谱法测定野木瓜中9种有机氯农药残留量

建立了悬浮固化-分散液液微萃取-气相色谱法测定野木瓜中9种有机氯农药残留量的方法。样品经石油醚提取、浓硫酸净化、悬浮固化-分散液液微萃取法浓缩后,用气相色谱-电子捕获检测器(GC-ECD)检测,外标法定量。结果表明,9种农药含量在1~100μg/L范围内线性关系良好,相关系数R2在0.99以上,方法检出限(S/N=3)为0.01~0.07μg/kg。9种有机氯农药在1.75,7.00,28.0μg/kg 3个水平添加下,平均回收率范围为83.3%~116.7%,相对标准偏差(RSD)范围为1.5%~14%,方法已用于野木瓜中9种有机氯农药残留的测定。     

毛细管气相色谱法测定沉香中20种有机氯农药残留量

应用毛细管气相色谱法测定沉香中20种有机氯农药的残留量。样品以乙酸乙酯提取,提取液用凝胶色谱-固相萃取(GPC-SEP)进行净化。采用DB-1701P石英毛细管色谱柱(30m×0.25mm,0.25μm)分离样品,电子捕获检测器进行检测。20种有机氯农药的线性范围均为1~50μg·L-1,检出限均为0.1μg·kg-1。方法用于沉香样品分析,加标回收率在95.8%~114%之间,测定值的相对标准偏差(n=6)在0.3%~3.8%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。     

茶叶中25种有机氯农药多残留气相色谱测定方法

利用气相色谱(GC)建立了茶叶中25种有机氯农药同时测定的方法。茶叶中有机氯农药残留通过正己烷-丙酮(体积比2∶1)溶液提取,浓缩后过弗罗里硅土柱净化,采用正己烷-乙酸乙酯(体积比9∶1)溶液淋洗,淋洗液吹氮至干后以正己烷定容供GC测定。标准工作曲线范围在0.005~0.500mg/L之间。在茶叶样品中0.005~0.100mg/kg水平有机氯混标加标回收率在71%~110%之间,相对标准偏差在4.6%~13.7%之间。除乙酯杀螨醇定量下限为8.0μg/kg以外,其余24种有机氯农药定量下限均为5.0μg/kg。     

凝胶渗透色谱-固相萃取联合净化气相色谱-质谱联用法测定动物性食品中30种有机氯农药的残留量

建立了猪肉、鸡肉、鱼肉和虾肉等动物性食品中30种有机氯农药残留的气相色谱-质谱联用检测方法。样品匀浆后,采用乙腈提取,以凝胶渗透色谱和弗罗里硅土固相萃取柱联合进行净化,气相色谱-质谱检测,以同位素内标法定量。30种有机氯农药的响应在5.0~500.0 μg/L范围内呈良好的线性,相关系数在0.996以上,各有机氯农药的检出限在0.2~2.7 μg/kg之间。以猪肉、鸡肉、鱼肉和虾肉作为代表性基质,进行5.0、10.0、20.0 μg/kg 3个水平的加标回收试验,回收率在55.0%~119.1%之间,相对标准偏差在0.4%~15.0%之间。该方法准确可靠,灵敏度高,样品净化效果好,能够满足动物性食品中有机氯农药多残留痕量分析的要求。     

固相萃取-气相色谱-质谱法测定水果中9种菊酯农药残留量

采用固相萃取-气相色谱-质谱法测定水果中9种菊酯农药的残留量。水果样品经丙酮-水(5+1)混合液匀质提取,二氯甲烷萃取,石墨碳柱净化。在气相色谱分离中用DB-5毛细管色谱柱为固定相,在质谱分析中采用选择离子监测模式。9种菊酯农药的质量浓度均在0.1~5mg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.000 6~0.01mg·kg-1之间。方法用于水果样品的分析,加标回收率在75.0%~106%之间,测定值的相对标准偏差(n=5)在1.6%~4.2%之间。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Effect of the Method of Modification of Zeolite X on Selectivity of Catalytic Methylation of Toluene

Theoretical and Experimental Chemistry - The effect of the method of modification of catalysts based on zeolite X by cesium and magnesium cations (ion exchange and impregnation) on the selectivity...     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

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 tetrabenzoporphins of the basis of isoindoline

Chemistry of Heterocyclic Compounds -