Detection hydrazide compounds

The creation of hydrazide probes often is based on the derivatization of a detectable molecule with a fezs-hydrazide compound. Although hydrazine itself (in the form of hydrazine hydrate) can be used in a methanolic solution to modify activated carboxylate molecules forming hydrazides, the availability of the bifunctional hydrazides provides a built-in spacer to accommodate greater steric accessibility. 

Reisfeld et al. (1987) described a hydrazide biotin labeling method (Table 7.20D) by which they could detect 1 pg of target DNA. Hydrazide compounds can be used similarly for a large number of other labels (enzymes, chromo- or fluorophores, electron-dense markers, etc.). Since the reaction is specific for ss nucleic acid, loops in duplices can be specifically labeled. 

There are many reports of the use of mass spectroscopy coupled to chromatography outlets for detection and identification of dmgs and metabolites. An example is compound 126 (99MI2, 99MI3). Carboxylic acids have been converted into hydrazides and hence into 3-substituted [l,2,4]triazolo... 

Isonicotinic acid hydrazide reagent 318 Isoprenaiine 395,396 Isoprenoid compounds 44 Isopulegol 59 Isoquercitrin 279, 280, 323 Isoquinoline alkaloids 46, 66, 262 Isorhamnetin 323 Isothiazolones, microbiocidal 45 Isothiocyanates 75 Isotopes, j8-radiation-emitting 41 -, detection limits 41 Itaconic acid 61... 

The most common structural motif of aluminum and gallium hydrazides is the centrosymmetric four-membered heterocycle with two exocyclic N—N bonds. The N-N distances of all these compounds fall in a very narrow range of about 145.5 pm on average with the most significant deviation (143.7 pm) detected for the diphenylhydrazido gallium derivative 14. The E2N2 heterocycles are planar with almost ideally equidistant E-N separations. As expected, the Al—N bonds of these compounds (196 to 199 pm) are shorter than the Ga—bonds (199 to 207 pm). 

A protein-binding assay (BA) coupled with hplc provided a highly sensitive post-column reaction detection system for the biologically important molecule biotin and its derivative biocytin, biotin ethylenediamine, 6-(biotinoylamino) caproic acid, and 6-(biotinoylamino)caproic acid hydrazide (71). This detection system is selective for the biotin moiety and responds only to the class of compounds that contain biotin in their molecules. In this assay a conjugate of streptavidin with fluorescamine isothiocyanate (streptavidin—FITC) was employed. Upon binding of the analyte (biotin or biotin derivative) to streptavidin—FITC, an enhancement in fluorescence intensity results. This enhancement in fluorescence intensity can be directly related to the concentration of the analyte and thus serves as the analytical signal. The hplc/BA system is more sensitive and selective than either the BA or hplc alone. With the described system, the detection limits for biotin and biocytin were found to be 97 and 149 pg, respectively. 

For all of the complexes 1, except la, the only detectable product of the reaction with 8 was the six-membered chelate 11. However, heating of compounds 11 up to their melting points (mp), or for prolonged periods of time in solution, led to conversion to 10 (Eq. 8).33,34 This reaction is analogous to the Wawzonek rearrangement of hydrazide-ylides (Eq. 9).39... 

The tendency of compounds RCN3=X to cyclize depends on the nature of X. When it is oxygen only open chain compounds are detected , and similarly for hydrazidic acids, RCNg=NNHAr, attempts to synthesize the cyclic form were failures . The latter type of compounds rearranged on treatment with acid to form semi-carbazides with retention of configuration. Guanyl azides can be isolated in open chain forms that cyclize on heating (reaction 94). 

The analytical applications of chemiluminescence fall into three broad categories. First, there are some chemiluminescent reactions that are catalyzed by specific compounds and that can, therefore, be diagnostic for the presence or quantitation of those compounds. For example, the hydrogen peroxide oxidation of the cyclic luminescent hydrazide luminol is catalyzed by transition metal ions such as Co(II), which can thereby be detected at a 10 pM concentration in a flow injection system (B33) and even down to 1 pM when the chemiluminescence is induced ultrasonically (K19). Other transition metal ions that have been similarly detected (in the 1-10 nM range) are Cr(III) (C13), Cu(II), and Ni(II) (S26). Other... 

The electrochemistry of hydrazides and their derivatives is of potential interest due to their biological importance as antituberculosis compounds. In this context the polarographic behaviour and reduction mechanism of various arylidene acid hydrazone has been studied in the past over a wide range of pH. The polarographic methods which has been applied previously for the determination of the hydrazide derivatives are insufficient for trace analysis. The detection limit for dc polarography is usually ca. 10 M but be higher under non-optimum conditions. 

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