反相高效液相色谱-质谱法测定喷气燃料中抗氧剂含量

分析喷气燃料中抗氧剂的真实含量对于研究和控制喷气燃料贮存的安全性具有重要意义。国外Cunningham等[1]用高效液相色谱 紫外检测器分析抗氧剂,国内目前普遍采用正相色谱,即以正己烷为流动相、用硅胶色谱柱和紫外检测器,直接测定喷气燃料中抗氧剂2,6 二叔丁基对甲酚的含量     

一种新的FIA导数光谱技术测定食盐中碘含量

提出一种新的流动注射导数光谱检测技术,即双光束同时扫描法。将自行研制的流动池比色装置分别安置在双光束检测器中样品光束和参比光束的光路中,实现同时扫描,获得响应曲线为一阶导数光谱。对该方法的原理和实验技术进行了讨论,基于碘酸根与碘化钾生成碘,并与淀粉生成蓝色络合物(λmax=574 nm)原理,确定了最佳实验条件,建立了一种导数光谱法测定加碘食盐中的碘含量。该法分析速度为130次/h,方法灵敏度比普通FIA法提高了1.8倍,测定结果的相对标准偏差为0.97%(n=9),方法可直接用于实际样品中碘含量的检测。     

固相萃取/高效液相色谱荧光法测定草珊瑚中苯并[α]芘残留

采用固相萃取方法,建立了草珊瑚中苯并[α]芘的高效液相色谱荧光测定方法。以正己烷为提取溶剂对草珊瑚样品进行提取,经中性氧化铝固相萃取柱净化样品后,用高效液相色谱荧光检测器检测,荧光检测器激发波长为370 nm,发射波长为425 nm,流动相为乙腈-水(85∶15),流速为1.0 m L/min。结果表明:苯并[α]芘在0~20 ng/m L浓度范围内线性关系良好,相关系数(r)为0.999 9,定量下限为0.36μg/kg,回收率为84.4%~101.9%,相对标准偏差(RSD)为1.6%~5.6%。该方法准确,灵敏度高,重复性好,适用于植物药材中苯并[α]芘残留的测定。     

双光束流动注射光度法测定生活用水中氯离子

将流动注射分析技术应用到双光束分光光度法中，对其理论和实验技术进行了研究，采用自行组装的流动注射系统进行了生活用水中氯离子的测定，获得满意结果。     

高效液相色谱荧光检测法快速测定天然生育酚中痕量苯并[a]芘

建立了一种快速、新颖的高效液相色谱荧光检测法测定天然生育酚中痕量苯并[a]芘.天然生育酚样品经中性氧化铝柱色谱富集和净化后在 XDB-C,18反相柱上,采用水-乙腈(体积比20比80)为流动相进行分离,采用荧光检测器进行检测,其激发波长为 260 nm,发射波长为 408 nm.苯并[a]芘的定量下限为 0.50 ng·g-1.加标回收率大于 77.9%.分析了 3 个不同试样,测定结果的相对标准偏差在 3.0%～10.6%之间.     

发光二极管诱导荧光检测器*

发光二极管诱导荧光检测器（LED-IF）是近十年来发展起来的一种微型化荧光检测器,在流动注射、毛细管液相色谱、毛细管电泳及芯片电泳等微流动分析系统中具有广泛的应用。本文讨论了LED-IF的4种光学结构,并对其主要器件,包括光源、滤光片、透镜、光纤、光电检测器以及检测池作了详细讨论,还介绍了LED-IF与其它技术的联用及其在生物、医药和环境样品检测中的应用,对未来的发展趋势作了展望。     

微滴溶剂萃取/低温电热蒸发ICP-AES联用新技术用于超痕量元素分析

Liu等[1] 首先提出了微滴溶剂萃取的新概念 ,并设计了微滴萃取装置 .Jeannot等[2 ] 用微升级的正辛烷对蛋白质溶液中键合 /未键合的黄体酮进行了萃取分离 .随后 ,文献 [3 ]报道了富集倍数超过 1 0 0 0的连续流动微滴溶剂萃取技术 .针对生物样品量少且昂贵这一情况 ,Kellert等 [4 ]提出纳升级溶剂超微滴萃取技术 .电热蒸发 (ETV)作为一种有效的微量试样 (固体、液体 )引入技术备受人们的关注[5,6 ] .微滴萃取技术与高灵敏度的 ETV-ICP-AES/ MS联用必将在微量试样的超痕量分析 /形态分析中发挥重要作用 .我们基于微滴溶剂萃取原理 ,设…     

毛细管电泳无接触电导检测研究进展

毛细管电泳(CE)电导检测(CD)是相对较灵敏和仪器结构简单的一项溶液分析技术,尤其是对于无生色团的无机离子分析更具有突出优势,因此,CE-CD技术近年来得到了较快发展[1],并已推出商品化的毛细管电泳电导检测器[2]。但CE和CD的偶联目前还存在如下几个问题:第一,加工适合于毛细管     

高效液相色谱-间接紫外检测法分析吡咯烷离子液体阳离子的研究

采用反相C_(18)色谱柱和紫外检测器,建立了吡咯烷离子液体阳离子的高效液相色谱-间接紫外检测分析方法。咪唑离子液体作为流动相的添加剂,既是背景紫外吸收试剂,又是改善分析物分离效果的有效组分。流动相中加入离子对试剂庚烷磺酸钠,可较好地改善吡咯烷离子液体阳离子的分离效果。在最佳色谱条件下,3种吡咯烷离子液体阳离子([MEPy]~+、[MPPy]~+和[MBPy]~+)可在13 min内得到有效的分离检测,[MEPy]~+、[MPPy]~+、[MBPy]~+的线性范围分别为0. 6～100 mg/L、1. 3～230 mg/L和3. 6～250 mg/L,相关系数(r)均大于0. 999,检出限分别为0. 2、0. 4、1. 1 mg/L。将该方法应用于实验室合成的同系物吡咯烷离子液体样品的检测,加标回收率为92. 2%～96. 7%。该方法准确、可靠,是一种有效分离和检测吡咯烷离子液体阳离子的实用方法。     

微流通道中溶质峰形不对称现象的研究

在微流控芯片分析中,由于微流通道微小的尺寸和检测器灵敏度的限制,容易出现诸如样品相对过载等引起溶质带偏离高斯分布(如前拖尾或者后拖尾等)的现象.引起溶质带峰形不对称的原因主要是由于吸附等温线^[1]和溶质带经过检测器时,由空间分布转化为时间分布所引起的扭曲所致^[2].     

Lateral protrusion and mesophase behaviour in pure and mixed states of model compounds of the type 4-(4′-substituted phenylazo)-2-(or 3-)methyl phenyl-4'-alkoxy benzoates

Two groups of the title compounds were prepared and investigated for their mesophase formation and stability. Each group constitutes five homologous series that differ from each other by the polar substituent X (CH₃O, CH₃, H, Cl, and NO₂). Within each homologous series, the number (n) of carbons in the alkoxy chain varies between 8, 10, 12, 14 and 16. The difference between the two groups of compounds lies in the orientation protrusion of the lateral methyl group attached to the central benzene ring. In the first group (Group I) the methyl substituent, introduced into the o-position with respect to the ester group, makes an angle of 60° with the long axis of the molecule. In the other series of compounds (Group II), the orientation angle is 120° as it is introduced into the position-3. All possible binary phase diagrams could be constructed in which the two components are corresponding positional isomers from either group. The study aimed to investigate the effect of inclusion of the lateral methyl group, as well as its spatial orientation, on the mesomorphic properties of the produced derivatives in their pure and mixed states. The compounds prepared in both groups were characterised for their mesophase behaviour by differential scanning calorimetry and polarised light microscopy. The nematic phase is the mesophase observed in most of the compounds prepared and their binary mixtures.     

Side group functionalized liquid crystalline polymers and blends VIII. Nematic and SmAre phase formation in hydrogen-bonded blends of smectic side group LC polymers and a low molar mass dopant

Hydrogen-bonded blends based on smectic side group functionalized LC copolymers containing 4-alkyloxybenzoic acid fragments (proton donor) and a non-mesogenic low molecular mass dopant 4-cyanophenyl pyridine-4-carboxylate or 4-methoxyphenyl-d₄ pyridine-4-carboxylate (proton acceptor) were obtained. The blends containing 10-35 mol % of low molecular weight dopant form nematic (I-N-SmA) or re-entrant SmA phases (I-SmA-N-SmAre). The temperature dependence of the order parameter S, the birefringence Δn, and the splay K ₁ and bend K ₃ elastic constants of the nematic phase were studied by ²H NMR spectroscopy and the Fréedericksz method of threshold transitions in a magnetic field. A mechanism for the destruction of the SmA phase and the formation of the nematic phase in the hydrogen-bonded blends is suggested.     

Novel mesogenic asymmetric diacylhydrazines: synthesis,mesomorphic behaviour and X‐ray study

The synthesis and liquid crystalline properties of a new series of diacylhydrazine derivatives (2a–g) are reported. All compounds of series 2 exhibit a smectic C (SmC) phase. The first homologues (2a, 2b) display a monotropic SmC mesophase, whereas the highest homologues (2c–g) exhibit an enantiotropic SmC phase. The liquid crystalline properties were investigated by differential scanning calorimetry, polarizing optical microscopy and X‐ray measurements.     

Polarity and steric effect of the lateral substituent on the mesophase behaviour of some newly prepared liquid crystals

Eight homologous series of 2- (or 3-) substituted phenyl 4?-(4?-alkoxy phenylazo) benzoates (In_a–h) were prepared in which, within each homologous series, the length of the terminal alkoxy group varies between 6, 8, 10 and 12 carbons, while the other substituent, X, is a laterally attached polar group that alternatively changed from CH₃, H, F, Br and CN. Compounds prepared were characterised by infrared and ¹H-NMR spectroscopy, and their mesophase behaviour investigated by differential scanning calorimetry and identified by polarised light microscopy. The results were discussed in terms of polarity and steric effects. The stability of the mesophase was correlated once with the dipolar anisotropy of the whole molecule and another with the dipolar anisotropy of the substituent, X. A comparative study was made between the investigated compounds and their previously prepared linear 4-substituted isomers, namely 4-substituted phenyl 4?-(4?-alkoxy phenylazo) benzoates (In_i–k).     

二溴对甲基偶氮溴羧与钡显色反应的研究与应用

研究了新显色剂二溴对甲基偶氮溴羧与钡显色反应的条件。在磷酸介质中,试剂与钡形成2:1的络合物,最大吸收波长为610nm,摩尔吸光系数为2.13×10~4L·mol~(-1)·cm~(-1),钡量在0～20μg/25ml范围内符合比耳定律。两倍的锶和五倍的钛不干扰,钙的允许量较大,方法用于直接测定钛酸钡烧结物中微量钡,结果满意。     

Synthesis and Study of the Fluorescent Character of a New Fluorescent Reagent 3-Pheny1-5-(2′-Carboxy1phenylazo)-2-Thioxo-4-Thiazolinone

Abstract

The paper reports the synthesis of a new fluorescent reagent 3-pheny1-5-(2′-carboxy1phenylazo)-2-thioxo-4-thiazolinone (3PRACP). The product has been purified by column absorption chromatography. Its conposition has been confirmed by elemental analysis, IR, HNMR and MS. We also studied its fluorescent properties At pH=5.6, 3PRACP can form a chelate with trace Cu²⁺ and when λ ex/λ em=305nm/405nm, the fluorescence is very intense. The fluorescent intensity has a linear relationship with the concentration of Cu²⁺ in the range of (0.1 – 48) × 10^?9 M. The sensitivity is 8X10^?9. Using the method, we detected trace copper in pork and vegetable, with good results.     

Synthesis of Some New 2-(4-Methoxybenzothiazol-2′-yl amino)-4-(2-chloro-4-trifluoromethylanilino)-6-(substituted thioureido)-1,3,5-triazine as Antifungal Agents

2,4,6-Trichloro 1,3,5-triazine was selectively reacted with new nucleophilic reagents such as 4-methoxy-2-aminobenzothiazole, 2-chloro-4-trifluoromethyl-aniline, and phenylsubstituted thiourea in alkaline medium to give 2-(4-methoxybenzothiazol-2′-ylamino)-4-(phenylthioureido)-6-(substitutedthioureido)-1,3,5-triazines. The structures of these compounds were confirmed by IR, ¹H NMR, ¹⁹F NMR, mass spectral data, and elemental analysis. The compounds show fungicidal activity against Alternaria alternata, Aspergillus niger, and Macrofomina.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

2-Substituted 5-oxo-5,6,7,8-tetrahydroquinazolines

Twenty novel 2-substituted 5-oxo-5,6,7,8-tetrahydroquinazolines in reactions of 2-formyl-1,3-cyclohexanedione and its 5,5-dimethyl- and 5-phenyl derivatives with 4-chloro- and 4-carbonylaminobenzamidines, 3- and 4-carbamidinopyridines, 2-carbamidinopyrazine, 2-carbamidino-5-trifluoromethylpyridine, 1-carbamidinopyrrolidine, 4-carbamidinomorpholine, and 1-carbamidino-3,5-dimethylpyrazole have been obtained.Riga Technical University, Riga LV-1658, Latvia; e-mail: marina@osi.lv. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 212–26, February, 2000.     

喹啉类主体分子的设计合成与阴离子识别

合成了系列 5 ( 8 羟基喹啉 )偶氮苯衍生物 ,研究了取代基对其吸收光谱的影响 ,比较了不同主体化合物对阴离子亲合能力的差异 .研究结果表明 :5 ( 8 羟基喹啉 )偶氮 4′ 甲基苯对F-具有选择性识别作用 ,主客体分子间形成 1∶1型阴离子配合物 ,其最大吸收波长为 5 0 8nm ,溶液颜色由无色变为红色 ,配合物的稳定常数为 2 5× 10 4mol-1·L .其它阴离子如AcO-,H2 PO-4,HSO-4,ClO-4,Cl-和Br-等均不影响主体与F-的显色反应 ,据此建立了选择性识别氟离子新体系 .     

Bis(O-nitrophenyl) Carbonate as a New Reagent for the Synthesis of Chiral Oxazolidin-2-ones

Bis(o-nitrophenyl) carbonate reacts under mild conditions with chirals 1,2-amino alcohols and, after addition of DMAP, affords the corresponding oxazolidin-2-ones in very good yields.