Hydrazines, detection

Thomas SW, Swager TM (2006) Trace hydrazine detection with fluorescent conjugated polymers a tum-on sensory mechanism. Adv Mater 18 1047-1050... 

Sensor devices -for hydrazine detection [HYDRAZINE AND ITS DERIVATIVES] (Vol 13) -pressure [OXYGEN-GENERATION SYSTEMS] (Vol 17) -inclusion compounds [INCLUSION COMPOUNDS] (Vol 14)... 

Fig. 2.12. (a) Fluorescence spectrum of sennoside A on a silica gel TLC plate after spraying with hydrazine. Detection Aminco-Bowman spectrofluorimeter, with a TLC-scanning accessory. Ex = excitation, Em = emission, (b), Scan of a TLC analysis of a Sennokot tablet extract obtained with a Zeiss chromatogram scanner. Peaks 1 3 sennoside B 2 = sennoside A 3 = sennoside C. 

According to the volcano plot, cobalt, iron, and manganese-based N4 macro-cyclic compounds provide the best catalysts for hydrazine oxidation. However, the electrocatalytic oxidation of hydrazine on a dinuclear mthenium phthalocyanine-modified electrode, coupled to a flow injection system, has until now provided the best linear response for hydrazine detection. 

Guerra SV, Kubota LT, Xavier CR, NakagaM S (1999) Experimental optimization of selective hydrazine detection in flow injection analysis using a carbon paste electrode modified with copper porphyrin occluded into zeolite cavity. Anal Sci 15 1231-1234... 

Wang J, Chen L (1995) Hydrazine detection using a tyrosinase-based inhibition biosensor. Anal Chem 67 3824-3827... 

Autoxidation of hydrazine occurs due to the presence of atmospheric oxygen. The autoxidation of hydrazine as evidenced by gas analysis and Infrared (IR) absorption measurements for hydrazine detection proceeds as represented in (1.7). The rapid autoxidation of hydrazine in the atmosphere is an advantage, as it means that hydrazine is not categorized as an environmental contaminant ... 

The acetone test reagent consists of a 0 1 per cent, solution of 2 4-dinitro-phenylhydrazine and is prepared as follows Dissolve 0-25 g. of 2 4-dinitrophenyl-hydrazine in 60 ml. of water and 42 ml. of concentrated hydrochloric acid by warming on a water bath cool the clear yellow solution and dilute to 250 ml. with water. The acetone test is considered negative when 5 ml. of the reagent and 4-5 drops of the distillate give no cloudiness or precipitate of acetone 2 4-dinitro-phenylhydrazone within 30 seconds. After a negative test is obtained, it is stron y recommended that the mixture in the flask be refluxed for 5-10 minutes with complete condensation and then to collect a few drops of distillate for another test. If no acetone is now detected, the reduction is complete. 

Derivatization is useful for detection of compounds such as amino acids and amines that lack easily detectable groups. For similar reasons, saccharides, as a class of compound, ehcit much interest. Two derivatization schemes have been reported using benzamide (61) and FMOC—hydrazine (62) to produce fluorescent products. 

Katritzky and co-workers studied the mechanism of this reaction in detail. His work involved a NMR study of 16 reactions of methyl-, phenyl-, 1,2-dimethyl-, and l-methyl-2-phenylhydrazine with /3-keto esters. In many cases starting materials, intermediates, and products were detected simultaneously. Most reactions proceed by nucleophilic addition of the less hindered hydrazine nitrogen atom to the keto carbon of the keto ester. For example, the pathway given in Scheme 3 for the reaction of methyl 3-oxobutanoate 9 with methyl- or phenyUiydrazine 2 (R = Me or Ph) was found to be dominant. The initially formed addition product 10 dehydrates to hydrazone 11, which then isomerizes to hydrazone 12. Intermediate 12 then cyclizes to pyrazol-3-one 13, which tautomerizes to the kinetically more stable pyrazol-3-otie 14 [87JCS(P2)969]. 

The pyrazole library was created sequentially using 10 mM solutions of the 1,3-dicarbonyl compound and 0.8 M solutions of the hydrazines, each introduced as a 2.5 pi slug [20]. This requires control of feeding of both reactant solutions so that the slugs enter the chip at the same time and mix thereafter. The residence time was 210 s. Thereafter, the reaction slugs were diluted on-chip by a 1 1 methanol-water stream at 8 pi min and detected. Analysis of the nature of the products and the degree of conversion was done using standards of reactant and product materials. 

Electrochemical detection has been achieved in a number of ways. The change in pH has been sensed with a traditional glass pH electrode antimony electrode or amperometrically via the pH sensitive oxidation of hydrazine... 

Unfortunately, there are no universal methods to detect all types of protein oxidation, because the products formed can be so diverse in nature. However, some forms of protein oxidation can be assayed using chemical modification (Davies et al., 1999 Shacter, 2000). In particular, the formation of carbonyl groups on proteins can be targeted using the reagent 2,4-dinitrophenyl-hydrazine (DNPH). This compound reacts with aldehydes to form 2,4-dinitrophenylhydrazone derivatives, which create chromogenic modifications that can be detected at high sensitivity in microplate assays or Western blot analysis (Buss et al., 1997 Winterbourn et al., 1999). 

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. 

W.Y. Hou and E. Wang, Flow-injection amperometric detection of hydrazine by electrocatalytic oxidation at a Prussian blue film-modified electrode. Anal. Chim. Acta 257, 275—280 (1992). 

Platinum was determined in seawater by adsorptive cathodic stripping voltammetry in a method described by Van den Berg and Jacinto [531]. The formazone complex is formed with formaldehyde, hydrazine, and sulfuric acid in the seawater sample. The complex is adsorbed for 20 minutes at -0.925 V on the hanging mercury drop electrode. The detection limit is 0.04 pM platinum. 

Figure 14 Representative fluorescence derivatization reagents used for PO-CL detection. DNS-CI, dansyl chloride DBD-F, 4-(A,A-dimethylaminosulphonyl-7-fluoro-2,l, 3-benzoxadiazole NDA, naphthalene-2,3-dicarboxaldehyde DNS-H, dansyl hydrazine DBD-H, 4-(iV,iV-dimethylaminosulphonyl-7-hydrazino-2,l,3-benzoxadiazole).

In earlier studies the in vitro transition metal-catalyzed oxidation of proteins and the interaction of proteins with free radicals have been studied. In 1983, Levine [1] showed that the oxidative inactivation of enzymes and the oxidative modification of proteins resulted in the formation of protein carbonyl derivatives. These derivatives easily react with dinitrophenyl-hydrazine (DNPH) to form protein hydrazones, which were used for the detection of protein carbonyl content. Using this method and spin-trapping with PBN, it has been demonstrated [2,3] that protein oxidation and inactivation of glutamine synthetase (a key enzyme in the regulation of amino acid metabolism and the brain L-glutamate and y-aminobutyric acid levels) were sharply enhanced during ischemia- and reperfusion-induced injury in gerbil brain. 

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