反相高效液相色谱法分离2-(氟苯基)-5-甲基苯并恶唑和2-(氯苯基)-5-甲基苯并恶唑的位置异构体

基于商品化的普通色谱柱建立了2-(氟苯基)-5-甲基苯并恶唑和2-(氯苯基)-5-甲基苯并恶唑邻、间、对位置异构体的分离检测方法。色谱柱为Inertsil ODS-SP C₁₈(250 mm×4.6 mm, 5 μm),以乙腈(A)和水(B)为流动相,在60%A~80%A间线性梯度洗脱15 min,流速为1.5 mL/min,柱温40℃,检测波长为310 nm。在质量浓度为2~200 mg/L范围内,2-(氟苯基)-5-甲基苯并恶唑邻、间、对位的异构体、2-(氯苯基)-5-甲基苯并恶唑邻、间、对位的异构体具有良好的线性关系,6种化合物的检出限(S/N=3)依次为0.0307、0.0293、0.0315、0.0226、0.0237、0.0226 mg/L。该法既为5-甲基苯并恶唑与氟苯或氯苯碳氢活化偶联反应制备的异构体混合物提供了一个快速检测的方法,又为2-芳基苯并恶唑类异构体的分离检测提供了参考。     

顶空进样气相色谱法检测啤酒中乙醛

建立了项空自动进样气相色谱法测定啤酒发酵液中乙醛含量的方法.检测条件优化为:顶空进样器平衡温度70℃,平衡时间30 min;色谱柱初始温度40℃,经程序升温10℃/min到180℃;柱流量1.2 mL/min,加盐量1.8g.对不同浓度的乙醛标准溶液进样测定,标准曲线证明线性良好,R2为0.999,线性范围2～64 m...     

酰胺类手性液相色谱柱对烯唑醇光学异构体的直接拆分

以正己烷-12-二氯乙烷为流动相,添加乙腈为改性剂,在酰胺类手性液相色谱柱上实现了对烯唑醇光学异构体的直接拆分.探讨了色谱柱、温度和乙腈的含量对拆分效果的影响,优化了色谱条件.实验结果显示:单独使用KR100-5CHI-DMB色谱柱时,烯唑醇中的光学异构体仅稍微分离;而单独使用Chirex 3001时,烯唑醇中的光学异构体则不分离;当KR100-5CHI-DMB与Chirex 3001串联使用时,烯唑醇中光学异构体能够得到很好的分离;在流动相中加入少量的乙腈作为极性添加剂,有助于改善异构体的分离度.当流动相为正己烷-12-二氯乙烷-乙腈(体积比8 ∶ 1 ∶ 1),流速1.0 mL/min,检测波长254 nm,柱温10 ℃时,烯唑醇中光学异构体得到很好的分离,分离度(R)为3.26.结果表明,酰胺类手性液相色谱柱能有效分离烯唑醇的光学异构体,方法简便、快速.     

气相色谱–质谱法快速测定塑料中磷酸三甲苯酯异构体

建立了气相色谱–质谱联用法,用于测定塑料材料中3种磷酸三甲苯酯同分异构体磷酸三邻甲苯酯、磷酸三间甲苯酯、磷酸三对甲苯酯。采用30℃/min升温速率,3种磷酸三甲苯酯同分异构体均在10 min内出峰,质量浓度在0.0~2.4 mg/L范围内与色谱峰面积呈良好的线性关系,相关系数不小于0.999 0,检出限均为0.1μg/L,加标回收率为90.6%~108.2%,测定结果的相对标准偏差为0.6%~4.8%(n=4)。该方法灵敏度高,精确度满足检测要求。     

气相色谱法测定木香中去氢木香内酯的含量

建立气相色谱法测定木香中去氢木香内酯的含量。选择HP–5毛细管色谱柱(30m×320μm,0.25μm),用FID检测器检测,进样口温度为280℃,柱温箱初始温度为150℃,保持3 min,以12℃/min升温至280℃,载气为氮气,流量为3.0 mL/min。去氢木香内酯的质量浓度在1.996～199.6μg/mL范围内与色谱峰面积呈良好的线性,线性相关系数r=0.999 5,加标回收率为98.26%～100.87%,6次平行测定结果的相对标准偏差为0.69%(n=6)。该方法简单,重现性好,可用于木香中去氢木香内酯含量的测定。     

顶空-气相色谱法测定聚碳酸酯聚合溶液中微量三乙胺

建立顶空-气相色谱法测定聚碳酸酯聚合溶液中三乙胺含量的快速测定方法。用乙醇将聚合溶液中的聚碳酸酯沉淀,滤液以二氯甲烷、乙醇、10%（质量分数）氢氧化钠溶液混合溶剂溶解定容,采用顶空-气相色谱法检测,色谱峰面积外标法定量。以DB-624柱（30 m×0.25 mm×1.4μm）为分离柱;载气为氮气,流量为1.2 mL/min;柱温升温程序：初始温度为80℃,以10℃/min的升温速率升至220℃;进样口温度为200℃;FID检测器温度为250℃;进样体积为0.6 mL;采用分流进样,分流比为20∶1。三乙胺质量浓度在0.2～2.0 mg/L范围内与色谱峰面积线性相关,相关系数为0.999 5,方法检出限为0.12 mg/L。样品加标回收率为98.47%～100.05%,测定结果的相对标准偏差为0.42%～1.34%(n=6)。该方法操作简单,适用于工业生产聚碳酸酯聚合溶液中三乙胺的批量快速检测。     

盐酸托莫西汀中S-异构体杂质含量的柱前衍生高效液相色谱法测定

以2,3,4,6-四-O-乙酰基-β-D-葡萄糖异硫氰酸酯(GITC)为柱前手性衍生化试剂,建立了柱前衍生化反相高效液相色谱(RP-HPLC)法测定盐酸托莫西汀中S-异构体杂质的方法。考察了碱化与衍生化试剂的浓度及反应时间对衍生化产率的影响,以及流动相组成对柱效、分离度、保留时间的影响,并讨论了结构因素对手性衍生和分离的影响。采用Agilent Zorbax SB-C18(250 mm×4.6 mm,5μm)色谱柱,以乙腈-四氢呋喃-水(体积比为41∶14∶45)为流动相,流速1.0 mL/min;检测波长254 nm,柱温35℃。在优化实验条件下,盐酸托莫西汀与S-异构体的分离度R1.5;S-异构体的检出限为0.15 mg/L,在0.5~8 mg/L范围内线性良好;精密度RSD为1.8%;按标准加入法计算,加标回收率为92%~99%;按外标法计算,加标回收率为94%~102%。该方法简便、可靠,可作为盐酸托莫西汀原料药中S-异构体杂质限量的质控方法。     

正相高效液相色谱法测定食物中8种维生素E异构体及维生素A

建立了正相高效液相色谱测定食物中8种维生素E异构体及维生素A的方法。样品中的维生素E异构体和维生素A经皂化和液液萃取,Waters ACQUITY^TM UPLC BEH Amide色谱柱(150 mm×3.0 mm, 1.7 μm)分离,体积比为90 : 10的正己烷与叔丁基甲基醚-四氢呋喃-甲醇(20:10:1, v/v/v)为流动相,荧光检测器和紫外检测器串联检测。4种生育酚在5.0~60.0 mg/L(r²≥0.9999)、维生素A和4种三烯生育酚在0.5~6.0 mg/L(r²≥0.9996)范围内具有良好的线性,各基质中目标物的检出限在20~60 μg/kg之间;9个组分在各基质中的加标回收率为79.2%~114.2%,相对标准偏差(RSD)为1%~12%。该方法简便、灵敏、可靠、环保,可用于食物中8种维生素E异构体以及维生素A含量的同时测定。     

气相色谱法测定聚异丁烯丁二酸酐中游离酸酐

建立气相色谱法测定聚异丁烯丁二酸酐中马来酸酐含量的方法。样品用有机溶剂萃取后进色谱柱分离。色谱柱采用HP-FFAP极性毛细管柱（30 m×0.32 mm,0.25μm）,载气为高纯氮气,分流比为1∶40,进样口温度为240℃,采用程序升温方式,初始温度为50℃,以10℃/min的速率升温至230℃,保持10 min,氢火焰离子化检测器温度为260℃。马来酸酐的质量分数在0～0.40%范围内与色谱峰面积线性良好,相关系数大于0.999。样品加标回收率为96.72%～99.35%,测定结果的相对标准偏差为1.172%～1.949%(n=6)。该方法操作简便、快捷、准确度高,可以满足实际生产需求。     

气相色谱-质谱法测定人工晶状体中2-氯乙醇

人工晶状体样品用丙酮超声提取使残留的2-氯乙醇(ECH)进入溶液中,所得提取液用气相色谱-质谱法(GC-MS)测定其中ECH的含量。GC分析条件:1采用ZB-624色谱柱,进样品温度180℃,分流比1比1;2载气为高纯氦气,流量为1.5mL·min~(-1);3升温程序:初始温度50℃,保持1 min;以5℃·min~(-1)速率升至100℃,保持1 min。MS分析条件:离子源温度230℃,接口温度250℃,电子能量70eV。以保留时间和质谱全扫描方式进行定性分析,质量数范围m/z35~500。以选择离子监测模式定量,质量数m/z43的条件下用外标法定量。方法的理论塔板数在56 753以上。ECH的线性范围为1.44~22.96mg·L-1,检出限(3S/N)为0.41mg·L~(-1)。用标准加入法测得方法的回收率为99.1%,测定值的相对标准偏差(n=5)小于5%。     

甲苯磺酸异构体的气相色谱分析

为克服在甲苯磺酸异构体定量分析结果中重复性和准确性差的问题，从多种色谱固定液中选出合适固定液，以正十十一烷作为内标物，优化了色谱条件，对气相色谱法研究甲苯磺酸乙酯异构体中的诸多影响因素进行了比较，确定了汽化室温度对于邻、间、对甲苯磺酸乙酯异构体准确测定的影响作用。     

Discrimination of Structural Isomers of Aromatic Compounds with EI Mass Spectra and Their Ionization Efficiency Curves of Dehydrogenated Fragment Ions

Wehavereportedtheeffectofovercrowdinginthemassspectfaofcondensedpolycyclicaromaticcompounds'-'.Themassdifferencebetweenamolecularionandthemostintensefragmentionintheionfamilyofthehighestvalencecorrespondstothenumberofovercrowdedhydrogenatomsdetachingfromtheparention,andtheirmasspatternsaredifferentwiththetypeofovercrowding,i.e.fjord-orcrab-likeovercrowding.Thehighabundanceofspecificfragmentionsat70Vwascorrelatedwiththeloweringoftheirappearanceenergies.Hereweinvestigatedthemassspectraandthemech…     

Structural characterization and differentiation of isomeric omega-bromoalkoxy derivatives of (E)-chalcone by means of mass spectrometry

Mass spectrometry with electron ionization and electrospray ionization have been applied to characterize and differentiate the isomeric ortho-, meta- or para-(E)-bromoalkyloxychalcones 1-15. The difference in the values of micro1-micro5 (i.e. the ratio of abundances of the selected fragment ions to those of the molecular ions) in the series of isomeric chalcones studied and the so-called "in-source" fragmentation induced by increasing cone voltage have been found to be important and reliable indicators differentiating the isomers studied.     

GC/MS和NMR分析5-氟-2-硝基苯乙醚还原反应的副产物

采用GC-MS分析5-氟-2-硝基苯乙醚的还原反应产物．在30．0m×250μmZB-5MS毛细管柱上,载气为He气,流量为0．8mL／min,起始柱温120℃维持3min,以20℃／min的速率升至260℃并维持10min,气化室温度270℃的条件下,5-氟-2-硝基苯乙醚还原的多种产物获得良好分离．通过对相应质谱图的解析,共鉴定出包括主产物在内的6种主要反应产物．经柱色谱分离提纯得到其中主要副产物,结合^1H-NMR确证该产物为未见报道过的副产物4-氟-2-氯-6-乙氧基苯胺．     

DNA targeted UVA photosensitization: characterization of an extremely photopotent iodinated minor groove binding DNA ligand

Previous studies have described UVA-induced DNA strand breakage at the binding sites of iodinated DNA minor groove binding bisbenzimidazoles. The DNA breakage, presumably mediated by the carbon-centred ligand radical produced by photodehalogenation, was also shown to be cytotoxic. The earlier studies included a comparison of three ligand isomers, designated ortho-, meta- and para-iodoHoechst, and the efficiency of photo-induction of strand breaks in plasmid DNA proved to be much higher for the ortho-isomer. We have now extended the comparison of the three isomers with respect to photo-induced cytotoxicity in K562 cells. Although the relationship between the extent of nuclear uptake and the concentration of the ligand in the medium was similar for the three isomers, assay of in situ dehalogenation in drug-treated cells indicated that the apparent cross-section for dehalogenation of the ortho-isomer was greater than 5-fold higher than that for the meta- and para-isomers. Also, analysis of clonogenic survival data showed that the dehalogenation event associated with ortho-iodoHoechst was a more efficient mediator of UVA-induced cytotoxicity in K562 cells than that for meta- or para-iodoHoechst. The number of dehalogenation events associated with 50% cell-kill for ortho-iodoHoechst (1.23+/-0.04 x 10(4)) was less than that for the para- (3.92+/-0.29 x 10(4)) and meta- (11.6+/-0.90 x 10(4)) isomers. Thus it is concluded that the photopotency of ortho-iodoHoechst, which is an important feature in the context of its potential use in clinical phototherapy, is due not only to more efficient UVA-mediated dehalogenation of the ligand, but also to greater cytotoxic potency per dehalogenation event.     

气相色谱-质谱联用法检测母乳脂肪中反式脂肪酸

建立了母乳中反式脂肪酸(TFAs)的气相色谱-质谱(GC-MS)检测方法,并应用于母乳脂肪中TFAs的检测。母乳用氨水水解,乙醚和石油醚提取脂肪,提取的脂肪加入C21: 0内标,用三氟化硼甲醇溶液在80℃水浴中冷凝回流15 min进行甲酯化,正己烷提取,上清液用GC-MS分析,内标法定量。在低、中、高加标水平上验证方法的准确度与精密度,结果显示该方法可用于母乳中18种TFAs及其同分异构体的检测,其中12种TFAs在母乳脂肪中的方法检出限为4.0~47.1 mg/kg,回收率为80%~113%, RSD为2.9%~14.5%(n=6)。TFAs在部分母乳脂样品中检出,含量为9.54~6.9 mg/kg。该方法定性、定量准确,可有效用于母乳中TFAs的检测,但仍存在脂肪酸本底干扰等问题,可结合银离子固相萃取柱预分离技术进一步完善。     

Separation of the positional isomers of phthalic acids in hydroorganic solvents using capillary electrophoresis

The positional isomers of phthalic acids (ortho-, meta-, and para-) and benzoic acid could be completely separated by capillary electrophoresis (CE). A simple CE method employing direct detection in mixed methanol/water buffers is presented. The effect of the electrolyte buffer system, including pH, buffer concentration, and organic solvent on the electrophoretic mobility of the analytes, is investigated. The electroosmotic flow is reversed using cationic surfactant and cetyltrimethylammonium bromide so that anions are separated under the co-EOF mode. The resolution of the analytes and selectivity could be improved by the adjustment of the methanol content. Ion association with the surfactant in methanol/water buffer is discussed. The validity of the method in terms of sensitivity, reproducibility, and linearity is also reported. The text was submitted by the authors in English.     

Fast temperature programming in routine analysis of multiple pesticide residues in food matrices

Flash gas chromatographic (GC) analysis of 15 organophosphorus pesticides commonly occurring in food crops was performed using the Thermedics Detection EZ Flash upgrade kit installed in the oven of a HP 5890 Series II Plus gas chromatograph. The temperature program and splitless time period were the main parameters to be optimized. In the first set of experiments wheat matrix-matched standards were analyzed both by: (i) the flash GC technique (resistive heating of a 5 m capillary column), and (ii) the conventional GC technique (moderate oven temperature programming of a 30 m capillary column). Using the flash GC technique, the analysis time was reduced by a factor of more than 10 compared to the conventional GC technique. Dramatically improved detectability of analytes was achieved due to much narrower peak widths. The flash GC technique was compared with another approach to faster GC analysis employing a 5 m column and fast temperature programming with a conventional GC oven. In comparison with this alternative, in the case of flash GC significantly better retention time repeatability was observed. The other superiority of resistive heating is very rapid cooling down (i.e., equilibration to the initial conditions) which contributes to the increased sample throughput.     

The relative stabilities of 11-vertex nido- and 12-vertex closo-heteroboranes and -borates: facile estimation by structural or connection increments

The relative thermodynamic stabilities of ortho-, meta- and para-isomers of 12-vertex closo-heteroboranes and -borates with different p-block heteroatoms were determined using density functional theory. More electronegative (smaller) heteroatoms tend to occupy non-adjacent, whereas less electronegative (larger) heteroatoms tend to occupy adjacent vertices in the thermodynamically most stable closo-diheterododecaborane isomers. The computed relative stabilities agree perfectly with experimental observations. The energy differences of para- and meta- relative to ortho-isomers of 12-vertex closo-heteroboranes generally depend on the extent of electron localization by a given heteroatom and show highly periodic trends, i.e. increase along the period and decrease down the group. The energy penalties for the HetHet structural feature (two heteroatoms adjacent to each other) for the 12-vertex closo-cluster are apparently significantly different from those for the 11-vertex nido-cluster. Reformulating two 11-vertex nido-structural features, i.e. Het(5k)(2) and HetHet, in terms of connection increments along with the additional structural feature HetHet(m) give the relative stabilities of various isomeric 11-vertex nido- as well as 12-vertex closo-heteroboranes and -borates, using one unique set of increments.