固相微萃取-GC-MS法测定水中的三苯胂和二苯胂酸

建立了一种同时测定水中痕量三苯胂和二苯胂酸的方法,使用巯基乙酸甲酯作为二苯胂酸测定的衍生化试剂,固相微萃取耦合气相色谱-质谱法(选择离子监测)同时测定三苯胂和二苯胂酸。优化了萃取纤维丝、萃取时间、衍生化等操作条件。同时对混合物测定的回收率、相对标准偏差和最低检测限进行了研究。方法的回收率大于95%,最低检测质量浓度分别为0.0005和0.0003 mg/L,6次测定的相对标准偏差分别为5.3%、7.6%。     

顶空液相微萃取-气相色谱质谱法快速测定饮料中苯和甲苯

建立了顶空液相微萃取-气相色谱质谱法测定饮料中苯和甲苯的方法。在对顶空液相微萃取(head-space liquid-phase microextraction,HS-LPME)实验条件优化的基础上,确定了最佳实验条件:以1.6μL正辛醇作为有机萃取剂,在萃取温度为50℃、萃取时间为5min,搅拌速度为750r/min,液滴离萃取瓶瓶塞2.0cm的条件下,萃取4.00mLNaCl含量为4.00mol/L的样品水溶液,取0.4μL的有机萃取剂直接进样。实验结果表明,苯和甲苯的富集倍数分别为94和191,方法检出限分别为0.090μg/L和0.093μg/L,线性范围为0.5～60μg/L(r>0.999)。将该方法应用于饮料中苯和甲苯的测定,回收率为93.6%和98.0%,相对标准偏差(RSD)为3.94%和2.69%。方法简单、快速且成本低、可信度高,适用于饮料和水样中苯和甲苯的快速分析。     

多波长线性回归紫外吸光光度法同时测定炼油厂污水中苯酚和苯胺

提出用多波长线性回归紫外吸光光度法同时测定炼油厂污水中的苯酚和苯胺.方法省去了萃取、蒸馏、显色等步骤,操作简单.对合成水样进行测定,相对标准偏差≤4.57%,相对误差≤±2.3%.对炼油厂水样进行测定并进行加标回收试验,苯酚和苯胶的回收率分别为99.4%～103.0%和97.2%～104.0%,结果良好.苯酚和苯胶的最低检出限分别为0.010和0.048μg·ml~(-1).     

顶空固相微萃取-气相色谱-质谱联用法测定海洋沉积物中的苯系物

利用顶空固相微萃取（HS-SPME）与气相色谱-质谱（GC-MS）联用建立了测定海洋沉积物中的苯、甲苯、乙苯、对二甲苯、间二甲苯、邻二甲苯以及苯乙烯等7种常见苯系物的检测分析方法。对无机盐的加入、平衡时间、萃取温度、萃取时间、解吸温度和时间等多个固相微萃取条件以及色谱条件进行了优化,内标法定量。结果表明：在0.500~20.0 ng/g范围内7种苯系物的线性关系良好,相关系数在0.995~0.999之间;方法检出限为0.0818~0.175 ng/g（干重）;日内和日间重现性较好,相对标准偏差分别为1.2%~3.6%（n=5）和0.4%~6.3%（n=3）;在每1.00 g海洋沉积物样品中2.0和15.0 ng加标水平下,平均加标回收率分别为61.7%~79.5%和77.1%~85.6%,相对标准偏差分别为5.4%~9.6%和3.9%~7.6%（n=5）。该方法快速、灵敏、简便,准确度高,重现性好,适合海洋沉积物样品中苯系物的痕量分析。     

液液萃取结合分散固相萃取-液相色谱串联质谱检测食品包装纸中的4-氨基偶氮苯

采用高效液相色谱-串联质谱法（LC-MS/MS）快速测定食品包装纸中偶氮染料释放的4-氨基偶氮苯.试样在0.5 mol/L氢氧化钠溶液的碱性环境下,用连二亚硫酸钠还原试样中的偶氮染料,用甲基叔丁基醚反萃取还原裂解产生的4-氨基偶氮苯,经氮吹、甲醇复溶后,用液相色谱-串联质谱进行测定,内标法定量.方法优化了色谱分离、质谱、液液萃取和分散固相萃取等条件.最优化条件下方法的检出限为0.13 mg/kg,定量限为0.42 mg/kg,加标回收率在90%~95%之间（添加水平分别为1、10、30 mg/kg）,相对标准偏差小于5%.     

硫化锌粉体中游离硫含量测试方法研究

介绍了关于硫化锌粉体中游离硫含量测定的样品处理和测试方法.以苯为萃取剂,用超声振荡方式进行萃取,并用单质硫的苯溶液标样代替有机硫标样标定库仑仪的回收率.回收率为112%～115%,测定结果的相对标准偏差为0.6%～2.4%.     

加速溶剂萃取-气相色谱-串联质谱法测定水产品中的苯并(a)芘

本文采用加速溶剂萃取技术进行样品前处理,通过对萃取溶剂、萃取温度、静态萃取时间的选择以及质谱条件的优化,研究建立了气相色谱-串联质谱法测定水产品中的苯并(a)芘的残留。结果表明:苯并(a)芘在2. 0～100. 0μg·L-1的标准曲线范围内线性关系良好,相关系数为0. 9994,方法检出限为0. 056 ng·g-1(干重),最低定量限为0. 18 ng·g-1(干重);两种添加量样品加标回收率平均值分别为93%和94%,相对标准偏差为12%和10%(n=7),该方法的准确度和精密度良好。二级质谱可有效排除水产品复杂基质的干扰,对实际水产品样品的测定也取得了较为满意的结果,本方法适合水产品中苯并(a)芘的痕量分析。     

全自动固相萃取-气相色谱-串联质谱法测定卷烟主流烟气中的3种多环芳烃

以全自动固相萃取技术净化主流烟气萃取液,建立了卷烟主流烟气中苯并［a］芘、苯并［a］蒽和屈艹 3种多环芳烃的气相色谱-串联质谱(GC-MS/MS)测定方法。以吸烟机抽吸卷烟,并以剑桥滤片捕集卷烟主流烟气,然后以含氘代苯并［a］芘内标的环己烷溶液萃取滤片,萃取液经全自动固相萃取仪净化后以GC-MS/MS分离检测。结果表明,苯并［a］芘、苯并［a］蒽和屈艹 的检出限分别为0.05、0.16和0.23 ng/cig,回收率为91.5%～102.1%,相对标准偏差(RSD)均小于5%。该方法的自动化程度高、操作简便、检出限低、重复性好,适用于卷烟主流烟气中苯并［a］芘、苯并［a］蒽 3种多环芳烃释放量的检测。     

中空纤维膜-液相微萃取-气相色谱/质谱法测定土壤中拟除虫菊酯类农药

采用中空纤维膜-液相微萃取-气相色谱/质谱法测定土壤中3种拟除虫菊酯类农药(联苯菊酯、氯氰菊酯、溴氰菊酯)。实验优化的样品制备和萃取条件为:土壤与水的质量比为1∶3,pH=4,超声时间为5 min,萃取剂为环己烷,萃取温度为25℃,搅拌速率为900 r/min,萃取时间为20 min。萃取后取1 mL萃取剂进行色谱分析。在此条件下,当采用SIM模式时,测得土壤中联苯菊酯、氯氰菊酯和溴氰菊酯的线性范围分别为0.01~25 mg/kg,0.5~50 mg/kg和0.5~50 mg/kg;检出限分别为0.003,0.020和0.040 mg/kg;相对标准偏差分别为4.3%,4.7%和8.6%。本方法可用于土壤中拟除虫菊酯类物质的快速测定。     

SPME/GC-MS测定水中痕量二苯氰胂的方法研究

采用衍生化固相微萃取-气相色谱-质谱(GC-MS)监测技术,对水中痕量二苯氰胂进行了测定,考察了衍生化试剂、萃取纤维、萃取时间等因素对方法灵敏度的影响.测定二苯氰胂的线性范围为2.14～137 μg/L,检出限为0.2 μg/L,相对标准偏差为10.4%,回收率为97%～102%.     

生物酶催化合成甲苯二氨基甲酸甲酯反应的研究

甲苯二氨基甲酸甲酯(TDC),是碳酸酯法制备甲苯二异氰酸酯(TDI)的中间产物.碳酸二甲酯(DMC)代替光气与2,4-二氨基甲苯(TDA)反应合成TDC,TDC经催化或热分解制得TDI,这是一条没有污染物产生的绿色合成路线.……     

Toluene abatement on Ag-CeO2/SBA-15 catalysts: synergistic effect of silver and ceria

As a typical volatile organic compound, toluene is a hazardous material for human health and the environment, and currently, the development of catalysts for its oxidation into CO₂ and water is crucial. The series of Ag-CeO₂/SBA-15 catalysts is synthesized by wetness impregnation techniques and characterized by a number of physical-chemical methods (nitrogen [N₂] physisorption, small angle X-ray scattering [SAXS], transmission electron microscopy [TEM], and temperature-programmed reduction [TPR]). The toluene sorption and catalytic properties in toluene oxidation are studied. Small silver [Ag] and cerium oxide [ceria, CeO_2] particles with sizes below 3 nm are predominantly formed in the ordered structure of Santa Barbara Amorphous-15 [SBA-15]. The interactions between the Ag and CeO₂ nanoparticles are established. Temperature-programmed desorption of toluene [TPD-C₇H₈] analysis shows that physical adsorption of toluene occurs on pristine SBA-15 material, while the introduction of either silver or ceria to SBA-15 leads to the appearance of additional strongly bound chemisorbed toluene on such sites. When both Ag and CeO₂ are introduced, only chemisorbed toluene is formed over the Ag-CeO₂/SBA-15 catalyst, and the highest catalytic activity in toluene oxidation is observed over this catalyst (T_98% = 233 °C, 0.2% C₆H₅CH₃) that is attributed to the synergistic effect of ceria [CeO_2] and silver [Ag].     

Microwave-assisted acid hydrolysis of toluene diamine conjugates in urine samples for biomarkers in toluene diisocyanate analysis

Toluene diamines (TDAs) in urine have been used widely to determine the amount of toluene diisocyanate (TDI) absorbed by humans. Conventional hydrolysis to prepare a sample of urine takes approximately 16 h. An attempt is made to apply microwave-assisted heating (MAH) to reduce the duration of analysis. Urine collected from rats exposed to a mixture of 2,4- and 2,6-TDI was diluted with non-exposed human urine 1/1250-, 1/500- and 1/250-fold. The urine samples were hydrolyzed by both conventional heating and MAH. The hydrolysis efficiency obtained using MAH significantly exceeded that obtained using conventional heating. Hydrolysis by MAH required only 20 min, 48 times faster than with conventional heating. The use of the MAH method in hydrolysis was demonstrated to be reproducible, timesaving and efficient technique in measuring the concentration of urinary TDAs.     

Toluene methylation on AlPO4-Al2O3 catalysts (5–15 wt.% Al2O3)

The alkylation of toluene with methanol over AlPO₄-Al₂O₃ (5–15 wt.% Al₂O₃) catalysts produces a mixture of xylenes (XYL) although trimethylbenzenes (TMB) were also found. The TMB selectivity increased with temperature at the expense of XYL selectivity. Isomer distribution was approximately 48, 24 and 27 mol% foro-, m- andp-XYL, and 74, 26 and 0 mol% for 1,2,3-, 1,2,4- and 1,3,5-TMB, both quite different from the equilibrium isomer composition. The catalytic activity increased with alumina content, however, it decreased on increasing the calcination temperature in the 923–1273 K range. Good correlations between catalytic activity and the increase in acidic properties with Al₂O₃ loading (as determined by base chemisorption, in the gas phase,versus pyridine and 2,6-dimethylpyridine) have been obtained.     

A LC Separation and Quantification of o‐Toluene Sulphonamide and its Related Positional Isomers Using a Cellulose tris(3,5‐dimethyl phenylcarbamate)

A simple, rapid, selective and sensitive high performance liquid chromatographic method was developed for the separation and quantification of o‐Toluene Sulphonamide and its positional isomers which is an intermediate of Zafirlukast drug substance using a chiral column. Elution time was below 10 min in normal phase mode and ultra violet detection was carried out at 220 nm. Efficient separation was achieved on a Chiralcel OD‐H column using of n‐Hexane and 2‐Propanol mixture (50:50 v/v) as isocratic at 1.0 mL min⁻¹ flow rate. Resolutions between m‐Toluene Sulphonamide and p‐Toluene Sulphonamide isomers of o‐Toluene Sulphonamide were found to be >; 2.5. The calibration graphs for m‐Toluene Sulphonamide and p‐Toluene Sulphonamide isomers of o‐Toluene Sulphonamide were linear (R² > 0.999) when ranging from the limit of quantitation to 0.5%. The method is found to be selective, precise, linear, accurate and also robust. It was used for not only Quality assurance but also monitoring the synthetic reactions involved in the process development of Zafirlukast. The liquid chromatographic method is found to be specific and reliable for the determination of unreacted levels of positional isomers in reaction mass. This method was successfully validated according to the International Conference Harmonization (ICH) guidelines (Validation of Analytical Procedures: Test and Methodology Q2).     

Pt/TiO_2光催化降解甲苯

选择甲苯作为研究对象 ,探讨了在不同光源照射、不同光催化剂的作用下 ,气相甲苯的降解情况 .结果表明甲苯在紫外杀菌灯照射下有明显的光化学反应发生 .在光催化剂作用、黑光灯照射时 ,甲苯发生光催化氧化反应 ;并对催化剂在降解甲苯反应中的失活原因做了初步探讨     

甲苯二异氰酸酯的气相色谱-质谱分析

采用气相色谱－质谱分析甲苯二异氰酸酯（TDI）,以TDI80为例,对测试过程中样品的存放、溶剂及色谱条件的选择、组分定量作了探讨,获得满意的结果。该法无需标样,具有定性定量准确、简便的特点。     

Phase equilibrium measurements of (methane + benzene) and (methane + methylbenzene) at temperatures from (188 to 348) K and pressures to 13 MPa

New isothermal pTxy data are reported for (methane + benzene) and (methane + methylbenzene (toluene)) at pressures up to 13 MPa over the temperature range (188 to 313) K using a custom-built (vapor + liquid) equilibrium (VLE) apparatus. The aim of this work was to investigate literature data inconsistencies and to extend the measurements to lower temperatures. For (methane (1) + benzene (2)), measurements were made along six isotherms from (233 to 348) K at pressures to 9.6 MPa. At temperatures below 279 K there was evidence of a solid phase, and thus only vapor phase samples were analyzed at these temperatures. For the (methane (1) + methylbenzene (3)) system, measurements were made along seven isotherms from T = (188 to 313) K at pressures up to 13 MPa. Along the 198 K isotherm, a significant change in the data’s p,x slope was observed indicating (liquid + liquid) equilibria at higher pressures. The data were compared with literature data and with calculations made using the Peng–Robinson (PR) equation of state (EOS). For both binary systems our data agree with much of the literature data that also deviate from the EOS in a similar manner. However, the data of Elbishlawi and Spencer (1951) for both binary systems, which appear to have received an equal weighting to other data in the EOS development, are inconsistent with the results of our measurements and data from other literature sources.     

PERVAPORATION SEPARATION FOR TOLUENE/n-HEPTANE MIXTURE BY POLYIMIDE MEMBRANES CONTAINING FLUORINE

Five kinds of polyimides were synthesized using five dianhydrides (including 2,2-bis[4-(3,4-dicarboxyphenoxy)- phenyl] propane dianhydride (BPADA),3,3',4,4'-diphenylsulfone-tetracarboxylic dianhydride (DSDA),4,4'- (hexafluoroisopropylidene)-diphthalic anhydride (6FDA),1,4-bis(3,4-dicarboxyphenoxy) benzene dianhydride (HQDPA), and 4,4'-oxydiphthlic dianhydride (ODPA)) and 2,2-bis[4-(4-aminophenoxy)phenyl] hexafluoropropane (BDAF) via the two- step method that included polyaddition to form the polyamic aci...     

Oxidative synthesis of benzamides from toluenes and DMF

An interesting oxidative procedure for the synthesis of benzamides has been developed through the cleavage of sp³ CH bond of methyl arenes with N-substituted formamides. Various benzamides were prepared in low to moderate yields. Even though the yields are moderate in general, this new synthetic procedure provides another option for benzamide synthesis.