Chromatographic behaviour of closely related aromatic amines on phenol-impregnated thin-layers

Summary The TLC behaviour of closely related aromatic amines on silica gel plates impregnated with phenol, o-cresol, p-nitrophenol, quinol, catechol and pyrogallol has been studied. An attempt has been made to correlate the chromatographic behaviour of amines with the equilibrium constants of the adducts formed by the interaction of amines with absorbed phenol. Suitable adsorbent system and solvent systems for an efficient separation of closely related isomers of this class of compound of physiological importance have been developed.     

Separation of aliphatic and aromatic amines by thin-layer chromatography using silica gel plates

Summary 28 different aromatic and aliphatic amines have been separated by TLC; 20 solvent systems were examined.     

Thermal characterization of modified phyllosilicates with aromatic heterocyclic amines

Vermiculite with the general formula of [Si_6.85Al_1.15][Mg_4.68Al_0.51Fe_0.63]O₂₀(OH)₄Ca_0.128Na_0.032K_0.094 was made to react with heteroaromatic amines α-, β- and γ-picolines in aqueous solution. The products were characterized by elemental analysis, infrared spectroscopy, X-ray diffraction and thermogravimetry. The intercalated nanocompounds maintained the crystallinity which changed the original interlayer distance of 1422 to 1474, 1456 and 1474 pm, for the sequence of the guest picoline molecules. Thermogravimetry data suggested the intercalation reactions were governed by basicity of amines.     

Environmentally benign chlorination and bromination of aromatic amines, hydrocarbons and naphthols

A simple and efficient procedure for chlorination and bromination of aromatic amines, hydrocarbons and naphthols by the action of aqueous hydrohalic acid and hydrogen peroxide is described. This environmentally clean and safe procedure involves in situ generation of the active halogen and its uncatalyzed reaction with the substrates in this study.     

Analysis of heterocyclic aromatic amines

Heterocyclic aromatic amines are formed in protein and amino acid-rich foods at temperatures above 150 °C. Of more than twenty heterocyclic aromatic amines identified ten have been shown to have carcinogenic potential. As nutritional hazards, their reliable determination in prepared food, their uptake and elimination in living organisms, including humans, and assessment of associated risks are important food-safety issues. The concentration in foods is normally in the low ng g⁻¹ range, which poses a challenge to the analytical chemist. Because of the complex nature of food matrixes, clean-up and enrichment of the extracts are also complex, usually involving both cation-exchange (propylsulfonic acid silica gel, PRS) and reversed-phase purification. The application of novel solid-phase extraction cartridges with a wettable apolar phase combined with cation-exchange characteristics simplified this process—both the polar and apolar heterocyclic aromatic amines were recovered in one fraction. Copper phthalocyanine trisulfonate bonded to cotton (“blue cotton”) or rayon, and molecular imprinted polymers have also been successfully used for one-step sample clean-up. For analysis of the heterocyclic aromatic amines, liquid chromatography with base-deactivated reversed-phase columns has been used, and, recently, semi-micro and capillary columns have been introduced. The photometric, fluorimetric, or electrochemical detectors used previously have been replaced by mass spectrometers. Increased specificity and sub-ppb sensitivities have been achieved by the use of the selected-reaction-monitoring mode of detection of advanced MS instrumentation, for example the triple quadrupole and Q-TOF instrument combination. Gas chromatography, also with mass-selective detection, has been used for specific applications; the extra derivatization step needed for volatilization has been balanced by the higher chromatographic resolution.     

Separation of aliphatic and aromatic amines by the ion interaction reagent RP-HPLC technique

Summary Ion interaction reagent RP-HPLC has been employed for the separation of some typical aliphatic and aromatic amines. The effects on retention of the alkyl chain length of the eluent, and of the eluent flow-rate have been studied. The use of solutions of hexylaminium-, octylaminium-and decylaminium-salicylate has been tested and compared, employing both conductometric and spectrophotometric detection. On the basis of the results obtained, the optimal experimental conditions can be chosen for each separation. Aliphatic and aromatic mono and diamines can be separated and detected, with an average sensitivity of the order of 40 ng without any pretreatment or derivatization. The retention data obtained for amines, compared with those obtained with the same ion interaction reagents for anions, help in the interpretation of the mechanism involved in the technique.     

Polyaromatic amines. Part 4: Synthesis of poly(ethynyl) linked aromatic amines

The title compounds were synthesised and characterised as part of a study into new aromatic amines for charge transporting materials. Each compound was characterised by cyclic voltammetry. A qualitative estimate of the intramolecular charge mobility was deduced from the difference between the first and second oxidation potentials.     

间硝基苯甲醛或间氯苯甲醛与芳香胺和芳香酮的Mannich反应

间硝基苯甲醛或间氯苯甲醛与芳香胺和芳香酮在20~25℃和催化量的浓盐酸催化下能直接进行Mannich反应, 用一步合成法合成15个1-芳基-3-芳胺基(3-硝基苯基)丙酮。产率为68~87%。产物结构经元素分析, IR, ^1H NMR, MS鉴定。本文还讨论了反应的适宜条件。     

杂环芳胺的结构与致突性之间的定量关系研究

基于杂环芳胺在生物体内的代谢特征 ,对 19种杂环芳胺类致突变化合物进行了半经验分子轨道法理论计算 ,求得了该类化合物的结构与致突变活性相关关系 .结果表明 ,杂环上氨基经羟基化后形成亲电活性中心的难易程度以及活性中心的稳定性等因素决定其致突性 ,计算预测值与实验结果相吻合 ,19种杂环芳胺的致突性实验值与PM 3计算结果之间存在非常显著的相关性 ,其相关系数r =0 .919,F =19.0 >F 0 .0 1 .     

HPLC post column derivatization of aromatic amines usingN-methyl-9-chloroacridinium triflate

An HPLC post column chemical derivatization procedure based on the interaction between an acridinium triflate and amines to form highly colored derivatives on-line is described for the determination of aromatic amines. Benzocaine and butesin, local anesthetic agents that contain the aromatic amine group, were used as model compounds. Reversed-phase HPLC conditions were developed for both the separation of analytes and the reaction between analytes and the acridinium triflate in the system. Three-dimensional knitted teflon shape coils and the internal diameter and length of the coils were important parameters in reducing band broadening and background noise.N-Methyl-9-chloroacridinium triflate was shown to be applicable to the determination of primary aromatic amines, selected secondary aromatic amines, hydrazides, and hydrazines. Application of the on-line chemical derivatization procedure to the analysis of pharmaceutical dosage forms containing procainamide (primary aromatic amine), isoniazid (hydrazide), and hydralazine (hydrazine) is also described.     

Investigation of 3-(carbazol-9-YL)-1,2-epithiopropane interaction with aromatic amines

In the reaction of 9-(2,3-epithiopropyl)-9H-carbazole with aromatic amines (aniline, 4-methoxy-, 4-methyl-, 4-fluoro-, 4-bromo-, 4-chloro-, 3-chloro-, 2-chloroaniline) and subsequent oxidation of the mixtures formed of propanethiols and disulfides with 25% H₂O₂ in basic solutions the respective disulfides have been synthesized. Carbazolyl-containing derivatives of the thiazolidine have been obtained.Published in Khimiya Geterotsiklicheskikh Soedinenii. No. 1, pp. 90–99, January, 2000.     

Dispersive liquid phase micro-extraction of aromatic amines in environmental water samples

A new, rapid and sensitive method for the determination of aromatic amines such as o-nitroaniline (NIT), alpha-naphtylamine (NAP), o-chloroaniline (CHL) in environmental water samples was developed with dispersive liquid phase micro-extraction coupled with high performance liquid chromatography. Preliminary experiments indicated that excellent achievements were obtained when chlorobenzene and acetonitrile were employed as the extraction solvent and dispersive solvent, respectively. Some other parameters that would have important effect on the pre-concentration of aromatic amines were investigated in detail. Under the optimal conditions, the method had excellent linear relationship between the peak area and the concentration for NIT, NAP and CHL in the concentration range of 1?～?50?µg?L^?1. The limits of detection and precisions of the proposed method were in the range of 0.1?～?0.7?µg?L^?1 and 6.3?～?9.7%, respectively. The proposed method has been validated with two real water samples, and the results showed that excellent spiked recoveries in the range of 92.8%?～?111.5% were achieved. All these demonstrated that the proposed method would be very useful and applicable for the determination of such pollutants in the future.     

Ionic liquid-based dispersive liquid-liquid microextraction for sensitive determination of aromatic amines in environmental water

Ionic liquid-based dispersive liquid-liquid microextraction was developed for the extraction and preconcentration of aromatic amine from environmental water. A suitable mixture of extraction solvent (100 μL, 1-butyl-3-methylimidazolium hexafluorophoshate) and dispersive solvent (750 μL, methanol) were injected into the aqueous samples (10.00 mL), forming a cloudy solution. After centrifuging, enriched analytes in the sediment phase were determined by HPLC-UV. The effect of various factors, such as the extraction and dispersive solvent, sample pH, extraction time and salt effect were investigated. Under optimum conditions, enrichment factors for 2-anilinoethanol, o-chloroaniline and 4-bromo-N,N-dimethylaniline were above 50 and the limits of detection (LODs) were 0.023, 0.015 and 0.026 ng/mL, respectively. Their linear ranges were 0.8-400 ng/mL for 2-anilinoethanol, 0.5-200 ng/mL for o-chloroaniline and 0.4-200 ng/mL for 4-bromo-N,N-dimethylaniline, respectively. Relative standard deviations (RSDs) were below 5.0%. The relative recoveries from samples of environmental water were in the range of 82.0-94.0%. Compared with other methods, dispersive liquid-liquid microextraction is simple, rapid, sensitive and economical.     

气相色谱-质谱法测定蜡笔中的芳香伯胺

建立了固相萃取-气相色谱-质谱(SPE-GC-MS)检测儿童蜡笔中苯胺等9种芳香伯胺的方法。先用正己烷除去蜡笔中的烷烃类物质,再以甲醇为提取剂在室温下超声提取两次,提取液经过浓缩后与还原剂连二亚硫酸钠在70 ℃下反应30 min,将反应后的溶液通过硅藻土固相萃取柱净化收集,然后采用HP-5M色谱柱分离,并用质谱进行检测。采用该方法成功地实现了9种芳香伯胺的分离检测。对于不同的芳香伯胺的定量限为5 mg/kg,实际样品的平均回收率为86.02%～102.43%。实验结果证明,该方法准确、稳定,可以用于蜡笔中芳香伯胺的实际检验。     

气相色谱-质谱法测定蜡笔中的芳香伯胺

建立了固相萃取-气相色谱-质谱(SPE-GC-MS)检测儿童蜡笔中苯胺等9种芳香伯胺的方法.先用正己烷除去蜡笔中的烷烃类物质,再以甲醇为提取剂在室温下超声提取两次,提取液经过浓缩后与还原剂连二亚硫酸钠在70℃下反应30 min,将反应后的溶液通过硅藻土固相萃取柱净化收集,然后采用HP-5M色谱柱分离,并用质谱进行检测.采用该方法成功地实现了9种芳香伯胺的分离检测.对于不同的芳香伯胺的定量限为5 mg/kg,实际样品的平均回收率为86.02%～102.43%.实验结果证明,该方法准确、稳定,可以用于蜡笔中芳香伯胺的实际检验.