2.4- Dinitrophenylhydrazine measurements

ROS can modify amino acid side chains, with histidine, tryptophan, cysteine, proline, arginine, and lysine among those most susceptible to attack (Brown and Kelly 1994). As a result, carbonyl groups are generated, and these carbonyl concentrations can be measured directly in plasma by using atomic absorption spectroscopy, fluorescence spectroscopy, or HPLC following reaction with 2,4-dinitrophenylhydrazine. 

In addition to the spectroscopic methods, there are a number of derivatization methods, in which a derivative of the carbonyl compound that can be easily separated and measured is formed. The most common of these is the use of 2,4-dinitrophenylhydrazine (DNPH), which reacts to form the hydrazone ... 

Digestibility, protein quality analysis in vitro, 131, 134, 136-139 in vivo, 127-128, 136-139 Dilatometry, to measure fat, 571 -572 Dimethyl sulfoxide (DMSO), plant cell wall, isolation, 706, 708 2,4-Dinitrophenylhydrazine (DNPH), determination of carbonyl compounds, 553-554, 558 (fig.) Diphenol oxidases inhibitors, 392... 

Carbon-14 content is measured by specially designed gas proportional counters (7. Aerosol samples are first converted to CO2 by combustion in a macroscale version of the thermal evolution technique. A clam shell oven was used to heat the sample for sequential evolution of organic and elemental carbon under equivalent conditions. Due to the possibility of thermal gradients, conditions in the macroscale apparatus were adjusted to produce the same recoveries of total carbon (yg C per cm of filter area) as for the microscale apparatus. Carbon-14 data are reported as % contemporary carbon based on the 1978 1 C02 content in the atmosphere. Aldehyde data referred to in this paper were obtained by impinger sampling in dinitrophenylhydrazine/acetonitrile solution and analysis of the derivatives by HPLC with UV detection (12). Olefin measurements were made by a specially designed ozone-chemiluminescence apparatus (13) difficulties in calibration accuracy and background drift with temperature limit its use to inferences of relative reactive hydrocarbon levels. 

C2. Cao, G., and Cutler, R. G., Protein oxidation and aging. I. Difficulties in measuring reactive protein carbonyls in tissues using 2,4-dinitrophenylhydrazine. Arch. Biochem. Biophys. 320, 106-114 (1995). 

F9. Floor, E., and Wetzel, M. G., Increased protein oxidation in human substantia nigra pars compacta in comparison with basal ganglia and prefrontal cortex measured with an improved dinitrophenylhydrazine assay. J. Neurochem. 70, 268-275 (1998). 

In the widely used colorimetric assay of SGOT and SGPT (R2), serum is incubated at 37 °G with phosphate-buffered L-aspartate/a-oxoglutarate or DL-alanine/a-oxoglutarate, respectively, the reaction terminated after a definite interval by addition of 2,4-dinitrophenylhydrazine in dilute HCl, and after a period at room temperature the hydrazones of oxalace-tate or pyruvate so formed are treated with dilute alkali and the optical density measured against water at 505 mp the results are read from standard curves of optical density against transaminase activity. 

An alternative procedure is applicable when the 2,4-dinitrophenylhy-drazone is known to be sparingly soluble in ethanol. Measure 1 millimole (0.198 g) of crystalline 2,4-dinitrophenylhydrazine into a 125-mL Erlen-meyer flask, add 30 mL of 95% ethanol, digest on the steam bath until all... 

Analysis of the Decomposition Products of Hydroperoxides. Some authors have monitored formation of some of the decomposition products of the lipid hydroperoxides. Direct spectrophotometric measurements of the formation of oxo-octadecadienoic acids at 280 nm are possible , as are measurements of secondary oxidation products like a-diketones and unsaturated ketones at 268 nm. The formation of various aldehyde products of lipid peroxide decomposition can be monitored by reacting them with 2,4-dinitrophenylhydrazine and, after HPLC separation, measuring at 360-380 mn the DNPH derivatives formed , althongh the sensitivity of this particular technique makes it very susceptible to interference. 

The possibility that some fraction of the ascorbic add in animal tissues is bound instead of free has continued to attract interest. It can be accepted as established that there is no bound ascorbic add in blood serum (S8). The ascorbic acid present in serum is freely dialyz-able and is not increased by various hydrolytic procedures when measured by the 2,4-dinitrophenylhydrazine method. The increases after hydrolysis reported earlier may be attributed to the production of other materials which readed with the 2,6-dichlorophenolindophenol used for titration. The possibility of bound ascorbic acid is, therefore, restricted to other tissues. 

Carbonyl compounds in oxidized lipids are the secondary oxidation products resulting from the decomposition of the hydroperoxides. They can be quantified by the reaction with 2,4-dinitrophenylhydrazine and the resulting colored hydrazones are measured spectrophotometrically at 430-460 nm. The carbonyl value is directly related to sensory evaluation, because many of the carbonyl molecules are those responsible for off-flavor in oxidized oil. The anisidine value is a measure of carbonyl compounds that have medium molecular weight and are less volatile (Frankel 1998). It can be used to discover something about the prior oxidation or processing history of an oil. 

Total carbonyl groups in the polymer chain were determined by the method of Imai and Kazusa (22) using 2,4-dinitrophenylhydrazine. The ketone associated with double bonds, -C(0)-(C=C)2-, was measured by UV spectra at Amax — 270 nm with = 2.7 X 103M 1 cm"1 (23). /3-Hydroxyketones, peroxides, and 1,2-glycols and a-hydroxyketones were decomposed respectively with dilute alkali (reverse aldol reaction), potassium iodide in sulfuric acid aqueous solution, and periodic acid in sulfuric acid aqueous solution and then measured by GLC. 

The carbonyl value measures secondary oxidation products and is determined by the 2,4-dinitrophenylhydrazine method. Initial carbonyl values are very low but they can increase to 100 or 150 mEq/kg when the oil is heated. 

The reagent solution included 1 g of 2,4-dinitrophenylhydrazine, 100 ml of ethanol, 5 ml of hydrochloric acid and 5 ml of distilled water. Before each measurement a fresh solution of... 

The reaction with 2,4-dinitrophenylhydrazine finished the modified iPP was used for molding the foils that were liable to UV sp>ectrophotometric measurements. Di (heptadecyl) ketone was used as model substance, ft was added in the amount of lwt.% to iPP, exposed to the reaction with 2,4-dinitrophenylhydrazine and thus a sample of standard was formed. According to the Beer s law it is valid ... 

Some enzyme reactions can be studied colorimetrically when either the substrate or product can be converted chemically to a coloured product suitable for measurement in a u.v. or visible light spectrophotometer. In the case of alanine aminotransferase, the pyruvate formed in the reaction can be converted to pyruvate-2,4-dinitrophenylhydrazone by the addition of 2,4-dinitrophenylhydrazine (DNP). Addition of sodium hydroxide yields a product with an absorption maximum at 505 nm. Other examples of colorimetric procedures will be found in the last section. Colorimetric procedures are used for enzyme assays in the sampling mode, whereby samples of the reaction mixture are analysed at certain fixed times after starting the reaction. Graphs depicting the reaction rate must then be constructed by plotting amount of substrate transformed against time. 

Total carbonyl content can be determined in oxidized lipids by the reaction with 2,4-dinitrophenylhydrazine, and the colored hydrazone (2,4-DNPH) derivatives are measured spectrophotometrically at 430-460 nm, and expressed as nmol hexanal/kg sample. The classical method for total carbonyl... 

Radiochemical techniques (Percy, 1964 Houseman, 1970 Barnard et aiy 1972) would appear to provide the least objectionable approach to the study of scission reactions. For uncross-linked rubber it was found that one bound ketone group was formed per scission event. This figure was obtained by the use of C -dinitrophenylhydrazine which was used to measure bound (aldehyde + ketone) and C -dime-done which was used to measure bound aldehyde, the bound ketone being obtained by difference. 

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