Determination of maleic hydrazide residues in cured tobacco by gas chromatography.

A rapid and sensitive method for measuring maleic hydrazide (6-hydroxy-2H-pyridazin-3-one) residues in cured tobacco is described. A mixture of free and bound maleic hydrazide is extracted with hydrochloric acid in which maleic hydrazide glycoside is simultaneously hydrolysed. The free maleic hydrazide obtained is methylated using dimethyl sulphate and the derivative is partitioned into chloroform and determined by capillary gas chromatography using a nitrogen-phosphorus detector. The limit of detection of maleic hydrazide is 5 ppm.     

Use of autoclave extraction and liquid chromatography with tandem mass spectrometry for determination of maleic hydrazide residues in tobacco

Maleic hydrazide has been extensively used as an effective growth regulator in tobacco sucker control. After application, maleic hydrazide distributes itself throughout the tobacco plant where it can exist as free, or forms glucoside conjugates with glucose, or becomes bound with lignin. Among them, free maleic hydrazide and its glucoside conjugates are extractable under conventional solvent extraction, while lignin bound maleic hydrazide is claimed to be non‐extractable. Herein, an autoclave extraction method has been developed to extract maleic hydrazide effectively, in which tobacco samples are extracted in an autoclave at 130°C for 1 h using 4 M hydrochloric acid. Under such pressurized hot acidic water conditions, lignin bound maleic hydrazide can be released. Meanwhile, glucoside conjugates are hydrolyzed. Total maleic hydrazide is detected by liquid chromatography coupled with tandem mass spectrometry, and the quantitative results coincide well with that obtained from the international standard method. The proposed autoclave extraction with liquid chromatography and tandem mass spectrometry method exhibits excellent linearity in the range of 5–200 mg/kg (R² = 0.9998), the matrix matched limit of detection and limit of quantification is 0.68 and 2.27 mg/kg, respectively. This method is simple and improves sample capacity, providing an effective approach to monitoring maleic hydrazide residues in tobacco.     

Direct introduction of a hydrazide group into a quartz crystal microbalance surface with dodecanoic hydrazide embedded in a hybrid bilayer membrane

Hydrazide group has a potential of immobilizing an antibody on a sensor surface in a way that ensures an optimal orientation and efficiency of the antibody. However, a multi-step chemical process, required for the preparation of a hydrazide group, is a barrier to its extensive application. This paper describes a new method to introduce a hydrazide group to a sensor surface by a one-step process using dodecanoic hydrazide. The method is based on an ability of the dodecanoic hydrazide to be incorporated into a hybrid bilayer membrane (HBM) layer, thereby presenting its hydrazide group to the surface. Liposome containing dodecanoic hydrazide was added to a hydrophobic self-assembled monolayer surface of a quartz crystal microbalance for the formation of a HBM. Then, the hydrazide group, presented in the surface of the HBM layer, was utilized for the oriented immobilization of an antibody via its carbohydrate moiety which was partially oxidized prior to the conjugation reaction. Activity and stable status of the incorporated dodecanoic hydrazide was revealed by the efficiency and reproducibility of the resulting immunosensor chip.     

Determination of Maleic Hydrazide in Potato Samples Using Capillary Electrophoresis with Dual Detection (UV‐Electrochemical)

A new method for the separation of a mixture of different herbicides (propham, chlorpropham, asulam, metamitron, linuron, and maleic hydrazide) using MEKC is proposed. A base‐line separation for the mixture of herbicides is achieved in less than six minutes. The detection limits obtained for all the herbicides were lower than 1.0 μM using UV detection. This separation method was used for the determination of maleic hydrazide in potato samples. If a dual (UV‐electrochemical) detection system is employed, chlorpropham can be also detected. The results obtained showed that electrochemical detection was ten folds more sensitive than UV detection for maleic hydrazide. The detection limit of the proposed method for maleic hydrazide employing electrochemical detection was 1.3 μg g^?1, this value is lower than 50 μg g^?1, which is the maximum residue level permitted for this plant growth regulator in potato samples. The results obtained in the work clearly demonstrate the advantage of using electrochemical detection coupled to capillary electrophoresis, using this detection the concentration limits are not compromised by miniaturization and the components required are simple and inexpensive.     

Acylation of hydrazides with acetic acid and formic acid

In peptide synthesis, hydrazides are important intermediates for the azide coupling method. A hydrazide is converted to the corresponding azide in the presence of an acid and a nitrite. When acetic acid (or formic acid) is used as the acid, partial acetylation (or formylation) of the hydrazide occurs as a side reaction. Formylation of the hydrazide is much faster than acetylation. Removal of the formyl group on the hydrazide with hydrazine and hydroxylamine was studied. The rate of deformylation with hydrazine treatment is faster than that with hydroxylamine treatment.     

A Novel Method for the Rapid Determination of Isonicotinic Hydrazide in Aqueous Solutions Using Reflectance Spectrophotometry and Colorimetry

A rapid method is developed for the quantitative determination of 5–35 g/L of isonicotinic hydrazide (INH, isoniazide) in aqueous media. The method is based on the formation of copper(I) oxide in the reaction of isonicotinic hydrazide with copper ions on the surface of indicator tablets and the subsequent recording of the analytical signal by reflectance spectrophotometry and colorimetry. Aluminum oxide is proposed as a solid-phase substrate for the production of indicator tablets. Isonicotinic hydrazide can be determined in the tablet form of the Isoniazid preparation.     

New phosphoramidite derivatives for the preparation of oligonucleotides containing a hydrazide group in any specified position of the oligonucleotide chain

A new versatile method for the preparation of oligonucleotides containing hydrazide groups in any position of the oligonucleotide chain by standard phosphoramidite automated oligonucleotide synthesis is proposed. The method is based on the use of a series of new modified components for oligonucleotide synthesis. An original protecting group for the hydrazide group is proposed. The presence of the hydrazide group in the obtained oligonucleotides and its high reactivity were demonstrated by the reaction with 4-methoxybenzaldehyde in solution. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2585–2595, November, 2005.     

2-取代-5-吡唑基-1，3，4-恶二唑类化合物的合成及生物活性

以5-吡唑甲酰肼和取代羧酸为起始物,运用"一锅煮"法合成了一系列2-取代-5-吡唑基-1,3,4-二唑.此外,还合成了1-苯酰基-2-吡唑酰基肼.初步生物活性测定结果表明,部分化合物有较好的杀菌和除草活性.     

Hydrazide as a Carboxyl Protecting Group deprotection by acidolysis

Elimination of the hydrazide group was studied with the model compounds N-benzoyl-glycine hydrazide and N-benzoyl-L -phenylalanine hydrazide, using phosphorus oxychloride, hydrogen bromide or hydrogen chloride in acetic acid, or 60% perchloric acid. It was found that treatment of N-benzoyl-L -phenylalanine hydrazide with perchloric acid gave N-benzoyl-L -phenylalanine in 100% yield and without racemisation.     

Biotinylation of Peptides/Proteins Using Biocytin Hydrazide

Biocytin hydrazide is widely used to biotinylate the carbohydrate moieties of glycoproteins. In this study, however, biocytin hydrazide was found to be able to directly biotinylate peptides and proteins. This phenomenon may cause false identification of non‐glycopeptides/non‐glycoproteins as glycopeptides/glycoproteins. Here, we report a systematic investigation of the reaction of peptides/proteins with biocytin hydrazide. Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry is used to analyze the biotinylation reaction between peptides/proteins and biocytin hydrazide. Peptides/proteins were reacted with biocytin hydrazide in diverse solvent systems with different biocytin hydrazide concentrations for up to 96 h at temperatures ranging from 4 °C to 65 °C. Singly biotinylated or multiply biotinylated peptides/proteins are observed. The efficiency of the biotinylation reaction increases with higher temperature, higher biocytin hydrazide concentration, or longer reaction time. The influence of buffer pH on the biotinylation reaction of peptides/proteins is less pronounced. The biotinylation efficiency is optimum at neutral pH. Data suggests that the peptides are biotinylated as efficiently as proteins. The observation that peptides/proteins condense only with biocytin hydrazide, 2‐iminobiotin hydrazide, adipic dihydrazide and phenyl hydrazine but not with biocytin HCl and 2‐iminobiotin, indicates that the biotinylation reaction of peptides/proteins occurs with the hydrazide moiety but not with biotin moiety of the biotinylated reagent. The postsource decay data of biotinylated P₁₄R indicates that biocytin hydrazide condenses with the guanidino group of arginine's side chain of P₁₄R, indicating that besides N‐terminal and lysine residue of peptides/proteins, arginine residue is capable of reacting with biocytin hydrazide.     

Fluorimetric determination of hemoglobin using spiro form rhodamine B hydrazide in a micellar medium

A novel fluorimetric method for the determination of hemoglobin (Hb) using spiro form rhodamine B hydrazide (RBH) as fluorogenic reagent in the presence of sodium dodecylbenzene sulfonate (SDBS) surfactant micelles is described. The method employs the reaction of Hb with RBH, a colorless, non-fluorescent spirolactam hydrazide in SDBS micelles to generate highly fluorescent product rhodamine B and hence leads to a large increase in fluorescence intensity. The fluorescence increase is linearly related to the concentration of Hb in the range 0.2-12.0 nmol l⁻¹ with a detection limit of 0.086 nmol l⁻¹ (3σ). The optimal conditions for the detection of Hb are evaluated and the possible detection mechanism is also discussed. The proposed method has been applied to the determination of Hb in human blood.     

Application of matrix solid-phase dispersion to the propham and maleic hydrazide determination in potatoes by differential pulse voltammetry and HPLC

The application of the matrix solid-phase dispersion (MSPD) process as sample treatment in connection with the electrochemical detection is studied for the first time. For this purpose, a novel methodology is introduced for the extraction of propham and maleic hydrazide herbicides from potatoes samples based in the MSPD process prior to their electrochemical detection. Potato samples disruption was done by blending them with C₈ bonded-phase and selective herbicide extraction was achieved by successive treatment of the blended with 50 mM phosphate buffer pH 7.4 (for maleic hydrazide) and methanol (for propham). The extraction procedure efficiency was estimated using differential pulse voltammetry in potato samples spiked with the herbicides yielding recovery values of 98% and 68% for propham and maleic hydrazide, respectively. No significant adverse effect of the MSPD process was observed on the herbicides electrochemical signals. For comparison, recovery studies using HPLC with UV detection were carried out and a good correlation in the results obtained by using both techniques was observed.     

Novel spectrofluorimetric method for the determination of sulfite with rhodamine B hydrazide in a micellar medium

A novel spectrofluorimetric method for the determination of sulfite using rhodamine B hydrazide as fluorogenic reagent in the presence of polyoxyethylene sorbitan monooleate (Tween 80) surfactant micelles is described. The method is based on the mixture of sulfite with rhodamine B hydrazide, a colorless, non-fluorescent substance in Tween 80 surfactant micelles which gives rhodamine B-like fluorescence emission. The fluorescence intensity increase is linearly related to the concentration of sulfite in the range 5-800 ng ml⁻¹ with a detection limit of 1.4 ng ml⁻¹ (3σ). The optimal conditions for the detection of sulfite are evaluated and the possible detection mechanism is also discussed. The method has been successfully applied to the determination of total sulfite in wines and compares well with the standard iodimetric method.     

Flow Injection Analysis of Maleic Hydrazide Using an Electrochemical Sensor Based on Palladium‐Dispersed Carbon Paste Electrode

A new analytical methodology for the electrochemical detection of the herbicide maleic hydrazide (3,6‐dihydroxypyridazine) by flow injection analysis is presented. This method is supported by the novel application of a palladium‐dispersed carbon paste electrode as an amperometric sensor for this herbicide. Maleic hydrazide shows anodic electrochemical activity on carbon‐based electrodes (glassy carbon or carbon paste electrodes) in all the pH range. This electrochemical activity is enhanced using metal‐dispersed carbon paste electrodes, especially at Pd‐dispersed CPE which displays good oxidation signals at 690 mV (0.050 M phosphate buffer pH 7.0), 140 mV lower than at unmodified electrodes. Under the optimized conditions, the electroanalytical performance of Pd‐dispersed CPE in flow injection analysis was excellent, with good reproducibility (RSD 3.3%) and a wide linear range (1.9×10^?7 to 1.0×10^?4 mol L^?1). A detection limit of 1.4×10^?8 mol L^?1 (0.14 ng maleic hydrazide) was obtained for a sample loop of 100 μL at a fixed potential of 700 mV in 0.050 M phosphate buffer solution at pH 7.0 and a flow rate of 2.0 mL min^?1. The proposed method was applied for the maleic hydrazide detection in natural drinking water samples.     

Reversed-phase liquid chromatographic determination of isoniazide in human urine as a test of the genetically predetermined type of biotransformation by acetylation

A new method of determination of genetically predetermined type of biotransformation by acetylation rate using reversed-phase liquid chromatography (RP-HPLC) was described. The method is based on determination of isonicotinic hydrazide (INH) which is excreted with the patient's urine during 24 h period after oral administration of 0.4 g of the drug. INH is used as pharmacogenetic marker. Precolumn derivatization of 4-chloro-5,7-dinitrobenzofurazan is used at RP-HPLC determination of INH and a new drug phosphabenzide (diphenylphosphinylacetic hydrazide, DPPAH) with specrtophotometric detection in urine. The limit of INH detection was 0.27 mug ml(-1) and the one of DPPAH was 0.82 mug ml(-1). As a result of pharmacokinetic investigation it was discovered that bimodal distribution by acetylation rate for DPPAH is less apparent than in the case of INH. It is shown, that immunomodulator xymedone (N-(beta-oxyethyl)-4,6-dimethyldihydropirimidon-2) is the acetylation inductor of xenobiotics.     

Application of rhodamine B hydrazide as a new fluorogenic indicator in the highly sensitive determination of hydrogen peroxide and glucose based on the catalytic effect of iron(III)-tetrasulfonato-phthalocyanine

A sensitive, selective and rapid spectrofluorimetric method is proposed for the determination of hydrogen peroxide using rhodamine B hydrazide as a fluorogenic substrate catalyzed by iron(III)-tetrasulfonatophthalocyanine. It is based on the oxidation of rhodamine B hydrazide, a colorless, non-fluorescent spirolactam hydrazide, by hydrogen peroxide which generates the highly fluorescent product rhodamine B. Under optimum conditions, the responses for hydrogen peroxide were linear from 2.0 × 10⁻⁸ to 2.0 × 10⁻⁶ mol L⁻¹, with a detection limit of 3.7 × 10⁻⁹ mol L⁻¹ in a 3.5 min reaction period. It can easily be incorporated into the determination of biochemical substances that produce hydrogen peroxide under catalytic oxidation in the presence of their oxidase. The possibility has been tested for the determination of glucose in human sera as an example.     

Synthesis of 2,5-Disubstituted 1,3,4-Oxadiazine and 1,3,4-Thiadiazine from Substituted Acetophenones and Acid Hydrazides Using [Hydroxyl(tosyloxy)iodo]benzene

A novel and direct method for the efficient synthesis of 2,5-disubstituted 1,3,4-oxadiazines from the reactions of [hydroxy(tosyloxy)iodo]benzene with substituted acetophenones, followed by the treatment with acid hydrazide and K₂CO₃, is reported. The methodology is also extended to the synthesis of 5-aryl-6H-1,3,4-thiadiazin-2-amine by using thiosemicarbazide under similar experimental conditions.     

A cationic cysteine-hydrazide as an enrichment tool for the mass spectrometric characterization of bacterial free oligosaccharides

In Campylobacterales and related ε-proteobacteria with N-linked glycosylation (NLG) pathways, free oligosaccharides (fOS) are released into the periplasmic space from lipid-linked precursors by the bacterial oligosaccharyltransferase (PglB). This hydrolysis results in the same molecular structure as the oligosaccharide that is transferred to a protein to be glycosylated. This allowed for the general elucidation of the fOS-branched structures and monosaccharides from a number of species using standard enrichment and mass spectrometry methods. To aid characterization of fOS, hydrazide chemistry has often been used for chemical modification of the reducing part of oligosaccharides resulting in better selectivity and sensitivity in mass spectrometry; however, the removal of the unreacted reagents used for the modification often causes the loss of the sample. Here, we develop a more robust method for fOS purification and characterize glycostructures using complementary tandem mass spectrometry (MS/MS) analysis. A cationic cysteine hydrazide derivative was synthesized to selectively isolate fOS from periplasmic fractions of bacteria. The cysteine hydrazide nicotinamide (Cyhn) probe possesses both thiol and cationic moieties. The former enables reversible conjugation to a thiol-activated solid support, while the latter improves the ionization signal during MS analysis. This enrichment was validated on the well-studied Campylobacter jejuni by identifying fOS from the periplasmic extracts. Using complementary MS/MS analysis, we approximated data of a known structure of the fOS from Campylobacter concisus. This versatile enrichment technique allows for the exploration of a diversity of protein glycosylation pathways.     

Form of the dihedral angle dependence of the spin-spin coupling constant JHNNH

Cyclic hydrazides (derivatives of phtalhydrazide,pyrozolidone-3, indazolone, cyclic hydrazide camphoric acid) are studied by the NMR¹H method. The size of the dihedral HNNH angle of several model compounds (pyrozolidone-3, cyclic hydrazide norcamphoric acid) are calculated by the MINDO/3 SSF MO LCAO method. It is shown that in the hydrazides with HNNH dihedral angle 0–70° the magnitude of the HNNH spin-spin interaction constant does not exceed 1 Hz. The form of its dependence on the dihedral angle is determined.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 3, pp. 363–366, 1989.     

Vanadametry

Summary A vanadametric method has been developed which has definite advantages over iodimetric assay and bromimetric assay for the estimation of isonicotinic acid hydrazide in tablets. The excepients such as lactose, glucose and starch do not interfere in the estimation of the hydrazide with vanadate. Unlike iodimetric and bromimetric assays, the vanadametric assay is rapid.See also Z. analyt. Chem. 160, 117 (1958).