Hydrazine reagents as derivatizing agents in environmental analysis – a critical review

Hydrazine reagents are a well-known group of derivatizing agents for the determination of aldehydes and ketones in liquid and gaseous samples. Within this article, the most important hydrazine reagents are critically summarized, and their major applications in different fields, including environmental analysis, food chemistry and industrial analysis are introduced. As 2,4-dinitrophenylhydrazine (DNPH) is the basic reagent for several international standard procedures, its properties are discussed in detail. Particular focus is directed on the chemistry of the hydrazine reagents, and chemical interferences are considered. Recent methods for the determination of various oxidants using hydrazine reagents are presented as well. Due to limited space, this review does not cover the related field of carbohydrate analysis, although many chemical aspects are similar.     

智能手机色度分析测定甲基紫与氢氧化钠反应速率常数

化学反应速率是反应动力学最基本的一个概念,化学反应速率常数的测定是基础化学实验中的必做实验。但该实验存在着试剂消耗量大等诸多缺点。本次实践活动从绿色化学理念出发,提出了通过将色彩理论与化学知识结合进行反应速率的测定,以达到节省实验所用试剂、提高学生对实验的兴趣等目的。首先调研了解学生对经典动力学实验的看法和利用智能手机进行化学实验的接受度,并在理论上对该方法的可行性进行了分析,再根据录制的甲基紫与NaOH反应的视频,通过色度分析获得了浓度随时间变化的曲线,由此测定了该反应的反应速率常数。该方法结合了互补光色理论、物质吸光定律等知识,只需利用智能手机和取色软件就可以开展动力学实验。     

The beginnings of Analytical Chemistry in Romania

The early time of Analytical Chemistry in Romania is presented. Starting from 1920, the famous schools of chemical analysis in the University of Cluj, Bucharest and Iassy were established. As an example, the team headed by Professor G. Spacu introduced the use of complex compounds as reagents in analytical chemistry. In this way many macro and micro gravimetric methods for elemental determination were proposed. Received: 1 March 1996 / Accepted: 20 May 1996     

The beginnings of Analytical Chemistry in Romania

The early time of Analytical Chemistry in Romania is presented. Starting from 1920, the famous schools of chemical analysis in the University of Cluj, Bucharest and Iassy were established. As an example, the team headed by Professor G. Spacu introduced the use of complex compounds as reagents in analytical chemistry. In this way many macro and micro gravimetric methods for elemental determination were proposed. Received: 1 March 1996 / Accepted: 20 May 1996     

Fluorometric Determination of Chlorzoxazone via Chemical Derivatization

Abstract

Parameters for the fluorometric determination of chlorzoxazone based on chemical derivatization with various fluorogenic reagents is presented. Among the reagents utilized were dansyl chloride, fluorescamine, 2,4-dihydroxybenzaldehyde and salicylaldehyde. The reagents were reacted with either intact chlorzoxazone or with the o-aminophenol and semicarbazide derivatives formed by reaction of the drug with aqueous base and hydrazine hydrate, respectively. The fluorophor formed by basic hydrolysis of chlorzoxazone followed by reaction with fluorescarnine was the most sensitive procedure investigated. Fluorescence was linear over the range 0.27–3.4 μg/ml. Application of the procedure to the analysis of chlorzoxazone in a dosage form and in spiked human plasma and urine samples gave accuracy in the range 1–4%.     

Simultaneous spectrophotometric determination of hydrazine and phenylhydrazine based on their condensation reactions with different aromatic aldehydes in micellar media using H-point standard addition method

H-point standard addition method (HPSAM) was applied to the simultaneous determination of hydrazine and phenylhydrazine. The method is based on the hydrazone formation reactions of hydrazine and phenylhydrazine in the presence of micellar sodium dodecyl sulfate (SDS). Mixed reagents of p-(dimethylamino)benzaldehyde (DAB) and p-nitrobenzaldehyde (NB) was used as selective chromogenic reagents for hydrazine and phenylhydrazine. Hydrazine and phenylhydrazine can be determined simultaneously in the range 0.020-0.50 and 0.20-10.0 μg ml⁻¹, respectively. The results allowed that simultaneous determination could be performed with the ratio 1:500 to 1:10 hydrazine-phenylhydrazine. Under working conditions, the proposed method was successfully applied to the simultaneous determination of hydrazine and phenylhydrazine in several synthetic mixtures and plasma and water samples.     

Capture-ROMP-release: application to the synthesis of amines and alkyl hydrazines

Application of a capture-ROMP-release strategy for the chromatography-free purification of Mitsunobu reaction products is described. Norbornenyl-tagged reagents are utilized for standard solution phase Mitsunobu chemistry. Post-reaction phase-switching is accomplished via in situ ring-opening metathesis polymerization (ROMP) followed by precipitation of the polymer with methanol. Release of the product from the polymer affords amines and alkyl hydrazine derivatives with good yields and purities.     

质谱在生命有机磷化学中的一些应用

讨论了质谱在生命有机磷化学中的应用,包括N-磷酰氨基酸、肽、五配位磷化合物、核苷-氨基酸磷酰胺的质谱裂解途径,有机磷试剂辅助下氨基酸的自组装成肽产物和机理。     

Reduced graphene sheets modified glassy carbon electrode for electrocatalytic oxidation of hydrazine in alkaline media

This paper describes the electrochemical properties of reduced graphene sheets (RGSs) for the electrocatalytic properties towards the hydrazine oxidation in alkaline media. The RGSs have been produced in high yield by a soft chemistry route involving graphite oxidation, ultrasonic exfoliation, and chemical reduction. The RGSs possess excellent electrocatalytic activity towards the hydrazine oxidation. In our opinion, RGSs are a potential electrode material for direct hydrazine fuel cells and electrochemical sensors for hydrazine detection.     

On the role of analytical chemistry in solvent extraction processing

Analytical chemistry plays a vital role in both the development and operation of any chemical process, and the process of solvent extraction as applied in hydrometallurgical operations is no exception. Because of the increasing attention being given today to solvent extraction as a means of separating metals in solution, it seemed appropriate that the analytical chemistry associated with solvent extraction studies, process development, and operations be reviewed. In this review, consideration is given only to analysis of the aqueous and organic phases for the determination of solvent components, rather than to the determination of metals in these phases. Furthermore, the major emphasis is placed on analytical methods which are applicable to process studied and plant control, and which require a minimum of instrumentation and operator skill. The importance of sampling is discussed first, and problems encountered in obtaining representative samples from the solvent, aqueous, and slurry phases are considered in some detail. This is followed by a review of methods of analysis which are directly applicable, or are considered as having application, to the analysis of the organic and the aqueous phases of the solvent extraction process. Analytical methods for the determination of the various extractants, modifiers, and diluents presently being used, or considered for use, in commercial solvent extraction processes are surveyed. First, those methods which are applicable to the determination of reagents in the solvent phase are considered, followed by those which are available for analysis of the aqueous phase for the determination of soluble components of the solvent phase. In both cases extractants, modifiers, and diluents are considered separately. Finally, some of the more obvious analytical needs, and areas where research is required in order that a more complete understanding of the solvent extraction process can be obtained, are discussed.     

Homocyclic o-dicarboxaldehydes: Derivatization reagents for sensitive analysis of amino acids and related compounds by capillary and microchip electrophoresis

Amino acids are essential compounds for living organisms, and their determination in biological fluids is crucial for the clinical analysis and diagnosis of many diseases. However, the detection of most amino acids is hindered by the lack of a strong chromophore/fluorophore or electrochemically active group in their chemical structures. The highly sensitive determination of amino acids often requires derivatization. Capillary electrophoresis is a separation technique with excellent characteristics for the analysis of amino acids in biological fluids. Moreover, it offers the possibility of precapillary, on-capillary, or postcapillary derivatization. Each derivatization approach has specific demands in terms of the chemistry involved in the derivatization, which is discussed in this review. The family of homocyclic o-dicarboxaldehyde compounds, namely o-phthalaldehyde, naphthalene-2,3-dicarboxaldehyde, and anthracene-2,3-dicarboxaldehyde, are powerful derivatization reagents for the determination of amino acids and related compounds. In the presence of suitable nucleophiles they react with the primary amino group to form both fluorescent and electroactive derivatives. Moreover, the reaction rate enables all of the derivatization approaches mentioned above. This review focuses on articles that deal with using these reagents for the derivatization of amino acids and related compounds for ultraviolet-visible spectrometry, fluorescence, or electrochemical detection. Applications in capillary and microchip electrophoresis are summarized and discussed.     

Application of pyridylazo and thiazolylazo reagents in flow injection preconcentration systems for determination of metals

Pyridylazo and thiazolylazo reagents are synthetic dyes widely used in analytical chemistry. These reagents are also very attractive for use in preconcentration systems. This paper covers the application of pyridylazo and thiazolylazo reagents in flow injection systems for the determination of metals. The article discusses flow injection preconcentration systems with solid-phase extraction, precipitation and cloud point extraction. The use of pyridylazo and thiazolylazo reagents in flow injection detection systems is also presented. The relative advantages and drawbacks of these systems are discussed. The application of pyridylazo and thiazolylazo reagents in new systems is presented in the concluding part of this review article.     

The application of strongly reducing agents in flow injection analysis : Part 5. Chromium(II) and vanadium(II) in acidic medium

Chromium(II) and vanadium(II) in acidic medium are applied as powerful reducing agents in flow injection analysis. Detection is done amperometrically. For the determination of nitrite with chromium(II), the limit of determination is 5 × 10^?6 mol l^?1 with a linear range up to 7.5 × 10^?5 mol l^?1, similar to the case of uranium(III). Vanadium(II) is less suitable for the determination of nitrite. Nitrate, hydroxylamine and hydrazine could not be determined with these reagents.     

衍生化-气相色谱-三重四极杆质谱法测定泼尼松龙中联氨

泼尼松龙是一种广泛用于临床治疗的肾上腺糖皮质激素药物,其中联氨的残留会直接影响用药安全,但目前国内外还没有出台相应的法律法规和标准来管控药物中联氨的残留限值。联氨具有强极性和强还原性,理化性质很不稳定,易被氧化,又因缺少发色团,相对分子质量太小,检测起来难度很大,需引入一种衍生化试剂,降低其极性,生成相对分子质量较大且理化性质稳定的衍生产物。该研究通过优化衍生化试剂、色谱-质谱条件、溶剂体系和衍生化条件,建立了衍生化-气相色谱-三重四极杆质谱法(GC-MS/MS)测定泼尼松龙中联氨残留的方法,并进行了方法学验证,结果满意。称取1 g泼尼松龙样品置于10 mL具塞离心管中,加入稀释溶剂(甲醇-二氯甲烷(14∶23, v/v))至刻度线,涡旋振荡至样品完全溶解后,吸取100 μL置于进样小瓶中,再加入丙酮900 μL,涡旋振荡混匀,样品在丙酮-稀释溶剂(9∶1, v/v)中同时完成稀释和衍生化反应后,再经GC-MS/MS检测分析。该研究的衍生化反应无需在添加冰乙酸和超声条件下进行,也无需再添加其他试剂进行萃取操作,联氨与丙酮可瞬间发生衍生化反应,直接实现泼尼松龙中联氨的快速测定。结果表明,联氨在1~12 μg/L范围内线性关系良好,线性相关系数(r²)为0.9999;检出限、定量限分别为0.03和0.10 mg/kg;进样精密度(relative standard deviation, RSD)为1.10%。加标回收率和重复性良好,加标水平分别为1、6、12 μg/L时的回收率为96.15%~96.46%,对应的RSD值为1.77%~2.12%。中间精密度良好,不同时间、不同人员在同一台仪器上测定结果的RSD值为1.77%。方法耐用性良好,通过改变色谱条件来研究检测结果受影响程度大小,在原条件、初始柱温±5 ℃、升温速率±2 ℃/min、柱流量±0.1 mL/min的条件下分别对加标6 μg/L的样品溶液中的联氨含量进行检测,检测结果的RSD值为2.58%。应用建立的方法测定泼尼松龙市售标准品和某药企提供的9个不同批次的泼尼松龙样品,均未检出联氨。该方法操作简便、准确可靠、灵敏度高、选择性好,可用于泼尼松龙中联氨的检测。     

一种检测水合肼荧光探针的合成与应用

基于香豆素类染料,设计合成了一种具有较高选择性和灵敏度,可在生理条件(pH 7.4)下检测水合肼的荧光探针,同时利用核磁共振和高分辨质谱对探针的分子结构进行了表征。基于水合肼进攻探针分子结构中的4-丁酸酯,生成酚氧负离子,同时发生分子内环化反应后生成具有强烈荧光的亚胺香豆素,实现了探针分子对水合肼的检测。光谱学研究表明,当向探针溶液加入水合肼(0~100μmol/L)后,探针溶液在绿色光谱区域(502 nm)呈现一个显著的荧光增强响应(增强至55倍)。并且,探针可以检测相对较低浓度的水合肼,检出限为1.7×10~(-7)mol/L。此外,相对于其他阴离子和亲核试剂,探针对水合肼的识别显示出较高的选择性和灵敏度。探针成功实现了细胞内水合肼的荧光成像,证明其在细胞成像中具有潜在的应用能力。     

Air monitoring of aldehydes by use of hydrazine reagents with a triazine backbone

Two hydrazine reagents, 4- N, N-dimethylamino-6-(4'-methoxy-1'-naphthyl)-1,3,5-triazine-2-hydrazine (DMNTH) and N-methyl-4- N', N'-dimethylamino-6-(4'-methoxy-1'-naphthyl)-1,3,5-triazine-2-hydrazine (MDMNTH) have been synthesized and used for the determination of aldehydes in air samples. Test tubes with the reagents coated on silica gel were prepared and used for monitoring of carbonyls in air. After elution with acetonitrile the hydrazones formed were separated by reversed-phase liquid chromatography. Detection was performed by UV-visible and fluorescence spectroscopy. The results were validated by use of standard atmospheres of the carbonyls and of nitrogen dioxide and ozone, as potential interferents. In comparison with established hydrazine reagents, e.g. 2,4-dinitrophenylhydrazine (DNPH), the results from use of MDMNTH correlate well; lower recoveries were obtained by use of DMNTH. The limits of detection for the new reagents are superior to those for DNPH, because of the possibility of fluorescence detection.     

Analytical applications of co-ordination compounds

The uses of metal complex compounds in the various fields of analytical chemistry are reviewed with particular reference to newer reagents and fresh applications of established reagents. The topics covered include precipitants, volumetric reagents, indicators and solvent extraction reagents. A new method for the gravimetric determination of gold with trans-dichlorobis(ethylenediamine) cobalt(III) chloride is included.     

Derivatization in mass spectrometry-3. Alkylation (arylation)

The review is devoted to alkylation (arylation) as a widely employed derivatization procedure for the protection of OH (carboxylic acids, phosphoric acids, sulfonic acids, alcohols, polyols, phenols, enols), SH (thiols) and NH (amines, amides) groups in order to increase volatility, to improve the chromatographic properties and, if possible, mass spectral properties of derivatives. Chemical aspects of derivatization and various alkylation (arylation) reagents and reaction procedures are described. Specific mass spectral (electron ionization, chemical ionization) features of derivatives helpful in identification, structure elucidation, profiling and quantitative determination of the above-mentioned polar compounds by coupled gas chromatography or high-performance liquid chromatography are discussed. Some common analytical applications of the procedures in organic chemistry, clinical chemistry, environmental chemistry etc. are briefly summarized.     

Mitsunobu Reactions Catalytic in Phosphine and a Fully Catalytic System

The Mitsunobu reaction is renowned for its mild reaction conditions and broad substrate tolerance, but has limited utility in process chemistry and industrial applications due to poor atom economy and the generation of stoichiometric phosphine oxide and hydrazine by‐products that complicate purification. A catalytic Mitsunobu reaction using innocuous reagents to recycle these by‐products would overcome both of these shortcomings. Herein we report a protocol that is catalytic in phosphine (1‐phenylphospholane) employing phenylsilane to recycle the catalyst. Integration of this phosphine catalytic cycle with Taniguchi’s azocarboxylate catalytic system provided the first fully catalytic Mitsunobu reaction.     

Organic synthesis using chemical tags: the third Leg of parallel synthesis

Increasing emphasis has recently been placed on the development of synthetic methods which effectively couple chemical synthesis and purification. For example, new formats for parallel synthesis are being developed which involve attachment of chemical tags to both reagents, reactants, and substrates to permit their chemoselective removal from reaction mixtures. The driving force for the development of tagged organic reagents is the ability to use standard solution-phase chemistry methods and reaction monitoring techniques (e.g. TLC and HPLC). In this mini-review, we will outline recent developments on the growing class of chemically tagged reagents, reactants, and substrates and highlight examples of their use in multistep synthesis.