DNPH

Heplanai (4). To silver tosylate (11 0 g, 38 mmol) in MeCN (100 mL) were added n-lodoheptane 3(7 0 g, 30 mmoO- The mixture protected from light was maintained 24 h at 20°, poured on ice, the product was extracted with El20 and the residua after removal of the solvenL i ias poured Into NasCOg (20 g) in DMSO (150 mL). After healing 5 mm at 1S0°C under N2, the akfehyda was separated as its 2.4-dimtrophenylhydrazone (DNPH) to afford 6.9 g of 4 DNPH (70%), mp 106-107 0. 

Aldehydes, ketones Apply sample solution and moisten with 2 N 2,4-dinitrophenylhydrazine in acetic acid After reacting, dry and chromatograph the 2,4-DNPH derivatives [14]... 

MTTC. A Fr expl contg PA 55, TNT 35 and TN-m-cresol 10%, melting below 100°, used for cast loading of HE projectiles. DNPh can be substituted for TN-m-cresol (Ref 4)... 

Salts of 2,4-Dinitrophenol. 2,4-DNPh forms numerous metallic salts, most of which are expl, eg ... 

DNPh forms low mp additive compds with ammonia or amines (aniline, toluidine, naphthyl-amine, etc), which on intimate mixing with oxidants (AN, K nitrate, Na nitrate, K chlorate,... 

K perchlorate, etc) form easily detonatable expls. Colver (Ref 5, 291) describes preparative methods and gives mp s of some of the additive compds. For example, 2,4-DNPh (mp 112-14°) combines with aniline to form an additive compd of mp 82° [See also GerP 72945 (1893) 73205... 

One of the most common addition compds to PA to lower its mp was trinitro-m-cresol, eg, in the Fr expl Cresylite. Other compds used were DNPh, DNT, DNM, MNM, MNPh, TNT, TN-m-X, DNB, TNB, etc... 

R = /)-methoxyphenyl (DMPG)2, (DMPH>2 R = p-nitrophenyl (DNPG)2, (DNPH)2... 

The identification and quantification of potentially cytotoxic carbonyl compounds (e.g. aldehydes such as pentanal, hexanal, traw-2-octenal and 4-hydroxy-/mAW-2-nonenal, and ketones such as propan- and hexan-2-ones) also serves as a useful marker of the oxidative deterioration of PUFAs in isolated biological samples and chemical model systems. One method developed utilizes HPLC coupled with spectrophotometric detection and involves precolumn derivatization of peroxidized PUFA-derived aldehydes and alternative carbonyl compounds with 2,4-DNPH followed by separation of the resulting chromophoric 2,4-dinitrophenylhydrazones on a reversed-phase column and spectrophotometric detection at a wavelength of378 nm. This method has a relatively high level of sensitivity, and has been successfully applied to the analysis of such products in rat hepatocytes and rat liver microsomal suspensions stimulated with carbon tetrachloride or ADP-iron complexes (Poli etui., 1985). 

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 O-ECAT reagent is a superior alternative to the use of 2,4-dinitrophenylhydrazine (DNPH Chapter 1, Section 1.1) in the study of protein oxidation. DNPH modification produces detectable complexes, but it does not provide information as to what amino acids are involved. O-ECAT modifies carbonyl end products of protein oxidation and in addition, it can provide exact information as to the amino acids that were oxidized. Mass spec analysis of modified proteins performed after proteolysis gives the exact amino acid sequences including the sites of O-ECAT reagent modification. The same antibody that is specific for the metal chelate portion of the standard ECAT reagent also can be used to capture and detect the O-ECAT... 

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. 

Carbonyl compounds for instance can be trapped by absorption in a reagent solution containing 2, 4-dinitrophenylhydrazine and hydrogen chloride. Details of this method are extensively described elsewhere (8). The principle of the method is that the carbonyl compounds, in case of rendering plant emission the aldehydes, react with the 2,4-dinitrophenylhydrazine and form 2,4-dinitrophenylhydrazones (2,4-DNPH s) according to the scheme. 

Determination of Carbonyl Compounds in Drinking Water by DNPH Derivatization and HPLC... 

Richardson SD, Caughran TV, Poiger T, Guo Y, Gene Crumley F (2000) Application of DNPH derivatization with LC/MS to the identification of polar carbonyl disinfection byproducts in drinking water. Ozone Sci Engin 22(6) 653-675... 

Figure 4.7 — Absorption spectra of 2,4-dinitrophenylhydrazine (2,4-DNPH), 4-nitrophenylhydrazine (4-NPH) and 2-nitrophenylhydrazine (2-NPH) in solution (solid line) and retained on C bonded silica of 60-100 nm particle size (broken line). TTie dotted line corresponds to the blank spectrum in the second type of experiment (cell packed with C,j bonded silica in distilled water). (Reproduced from [97] with permission of Elsevier Science Publishers).

Scheme 19. Reaction conditions i. PCI5, 100°C ii, Ha-Pd/C iii, 2,4-DNPH iv, HCl in AcOH ...

HPLC methods with fluorescence detection have also been developed for the determination of nitro-policyclic aromatic hydrocarbons (PAHs) (among which 9-nitroanthracene and 1-nitronaph-thalene) [238] in atmosphere. Samples have been collected in a standard high-volume sampler with a Teflon-coated glass fiber filter, and the Soxhlet extraction was performed with dichloromethane as the solvent. RP HPLC/UV techniques are used for the determination of aldehydes, ketones, and carbonylic compounds after derivatization with DNPH [239],... 

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