Carbonyl compounds, 2,4-DNPHs

Aromatic hydrocarbons, carbonyl compounds (DNPH derivatives), herbicides, hydrazines, insecticides, metal ions, fat-soluble vitamins, lipids, lipophiUc dyes, polycyclic aromatic hydrocarbons (PAHs)... 

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). 

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... 

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],... 

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 ... 

Other approaches to collection of the carbonyl compounds include the use of impingers containing the DNPH in a solvent such as acetonitrile (e.g., Grosjean and Fung, 1982 Lipari and Swarin, 1982), scrubbers (e.g., Dasgupta et al., 1988, 1990 Lee and Zhou, 1993), mist chambers (e.g., Cofer and Edahl, 1986 Munger et al., 1995 Khare et al., 1997), and condensation collectors (Dawson and Farmer, 1988). 

Sirju, A.-P., and P. B. Shepson, Laboratory and Field Investigation of the DNPH Cartridge Technique for the Measurement of Atmospheric Carbonyl Compounds, Environ. Sci. Technol., 29, 384-392 (f 995). 

In order to express the absorbances obtained by this method in terms of moles of carbonyl, the spectral absorbances of DNPH derivatives of several purified carbonyl compounds were measured. At 430 nm, molar extinction coefficients of 16,000 and 21,350 were determined for the saturated and unsaturated carbonyl compounds, respectively, whereas at 460 nm, the values were 12,450 and 28,100, respectively. Based on the present methodology and use of 1-cm cuvettes, the above equations were derived (Henick et al., 1954). 

Describes a simple and sensitive spectrophotometric method to estimate the content of total carbonyl compounds in rancid fats and foods by trapping them with 2,4-DNPH the technique determines total carbonyls, including those that are nonvolatile, decreasing the ability of the assay to correlate well with sensory data. Although gas chromatographic techniques are better suited for determining volatile carbonyl compounds from lipid oxidation, this is still the classical colorimetric assay. 

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... 

Other types of diffusive sampler have been less widely applied for indoor air studies. These include tube type samplers that are solvent desorbed and radial type samplers consisting of a cylindrical adsorbent surface that has a short diffusive path resulting in an effective uptake rate that is typically 100 times that of the tube type sampler (Cocheo, Boaretto and Sacco, 1996). One type of radial sampler developed for measuring carbonyl compounds in indoor air comprises silica gel coated with 2,4-DNPH as the adsorbent within a sintered polyethylene tube that acts as a diffusive membrane (Uchiyamaa, Aoyagi and Ando, 2004). 

If the compounds are derivatized with DNPH and the derivatives are determined by GC or HPLC, the equivalent concentrations of the parent carbonyl compounds in the sample may be stoichiometrically determined as shown below in the following example. 

Zwiener, C., T. Glauner, and F.H. Frimmel. 2002. Method optimization for the determination of carbonyl compounds in disinfected water by DNPH derivatization and LC-ESI-MS-MS. Anal. Bioanal. Chem. 372 615-621. 

The GC separation of 2,4-dinitrophenylhydrazones has been studied by a number of workers [52-55], Non-polar stationary phases of the SE-30 and SF-96 type were utilized for this purpose at temperatures of 200—250°C, mostly with temperature programming. Retention indices of the 2,4-DNPHs of some carbonyl compounds on OV-type stationary phases are presented in Table 5.5. Using columns with a higher separation efficiency, some 2,4-DNPHs provide two peaks. The discussion of whether these artifacts are caused by thermal decomposition or syn-anti isomerization of the derivatives seems to favour the latter. The ratio of the areas of the peaks of the two derivatives depends on the polar-... 

Dinitrophenylhydrazones (DNPHs) were applied to the GC analysis of keto acids. As with carbonyl compounds, they are prepared by reaction with 2,4-dinitrophenylhydrazine and are also used mainly for the preliminary isolation of keto acids. They can be isolated from a dilute aqueous sample by adsorption on activated carbon and selective desorption [178] hydrazones of aldehydes with a methyl formate-dichloromethane mixture and hydrazones of keto acids with a pyridine-water azeotropic mixture. Hydrazones of acids are released from their pyridine salts with methanol containing hydrogen chloride. After... 

The extent of oxidation can also be assessed by the analysis of oxidized fatty acids by spectroscopic means such as IR and NMR techniques (102). Moreover, GC-MS for volatile profile analysis (103) and HPLC for determination of DNPH derivatives of nonvolatile higher carbonyl compounds (62) provide qualitative... 

The formation of hydrazinohydrazones [similar to compounds (I) have been reported for the reaction of unsaturated carbonyl compounds with dialkyl hydrazines. Hence, the existence of different products means that the quantitative yield of each of them is not enough, as is necessary for GC analysis of derivatives. It is quite probable that the same anomalies can take place in the reactions of unsaturated carbonyls with other reagents. For example, unsaturated 2,4-DNPHs seem unstable at the high temperatures of injectors and GC columns. This fact explains the small number of published RI data for the derivatives of these compounds and the necessity to search the new types of derivatization reactions for them. 

The milk and cream were centrifuged, and the fat fraction was removed. The fat was extracted with carbonyl free hexane, and the fat extract was immediately reacted with 2,4-dinitrophenylhydrazine. The carbonyl compounds formed respective 2,4-dinitrophenylhydrazones (2,4-DNPH). The hydrazones were separated into monocarbonyls and then further purified using thin layer chromatography (18). Alkanal 2,4-DNPH were analyzed by gas chromatography using a 1.83 m glass column (i.d. 4 mm) packed with 2% OV-1 on acid washed Chromosorb W ( 180-200 mesh) (18,19). ... 

Classification of the structures of various carbonyl compounds from the UV and IR spectra of their 2,4-DNPH... 

Low molecular weight carbonyl compounds in ETS were collected as their 2,4-DNPH derivatives. 

Carey and Persinger [128] described the derivatization of a number of simple aliphatic carbonyl compounds such as formaldehyde and acetaldehyde with 2,4-DNPH. The derivatives were analyzed on a Corasil II column and monitored at 254 nm. Two HPLC systems were reported for separating the 2,4-DNPH derivatives of thirteen carbonyl compounds ranging from acetaldehyde and acetone to benzaldehyde and salicylaldehyde [136]. One system used a column packed with 1% tris-(2-... 

Other methods for determining carbonyl compounds involve derivatization followed by column chromatography or by HPLC or by GC. Total carbonyls in lipid extracts are converted to their 2,4-DNPHs by using a column of diatomaceous earth impregnated with 2,4-DNPH, followed by extraction and spectrophotometric measurement at 340 nm. By reaction with methylhydrazine. 

IWenty-two carboxylic acids and carbonyl compounds (e.g., oxalacetic acid, glyoxylic acid, glyceraldehyde, glyoxal, acetone, isobutyraldehyde, benzaldehyde, cyclohexanone) were separated as their 2,4-dinitrophenylhydrazine (DNPH) derivatives on a 55°C C g column (A = 360 nm). A complex 100/0 0/100 (1/1.4/6... 

Carbonyl compounds Carbonyl compounds in sample converted to 2,4 dinitrophenylhydrazones, applied to thin-layer plate and plate developed. Separated 2,4-DNPH compounds located as yellow or brown colours upon spraying plate with 2% sodium hydroxide in 90% ethanol. [20]... 

Now, it is worth noting (Table 9.4, 3a) that when the carbonyl group (C=0) in the aldehyde or ketone is unhindered, a second equivalent of carbonyl compound can be added to the hydrazone with the formation of an azine. The aryl-substituted hydrazines, for example, phenylhydrazine (C6H5NHNH2) and in particular 2,4-dinitrophenylhydrazine ( 2,4-DNPH ) (Table 9.4,3b) frequently form crystalline hydrazones. For many years (in a largely pre-spectroscopic era), it had been accepted that if the melting points of two derivatives (e.g., 2,4-DNP and oxime) of an unknown ketone or aldehyde corresponded to values found in published tables or lists of those previously reported, then the ketone or aldehyde had been identified. Generally, the method was successful but clearly dependent on ready access to the appropriate tables or lists. 

What would be observed when each of the carbonyl compounds in the table is mixed with 2,4-DNPH ... 

A derivative was formed between 2,4-DNPH and an unknown carbonyl compound. 

DNPH derivatization is a method used to measure aldehydes and ketones. Nucleophilic addition is used to convert the carbonyl compounds to stable hydrazine derivatives prior to analysis. Either GC methods or HPLCAJV analysis can be used to detect the derivatives. 

Weigh about 2 g sample, containing 0.5-50 0.g carbonyl (as CO) into a 25-mL volumetric flask. Add 2 mL MeOH to a second flask for the reagent blank. To each flask, add 2 mL 2,4-DNPH solution (0.1 g 2,4-DNPH in 50 mL MeOH containing 4 mL cone. HCl dilute to 100 mL and discard after 2 weeks), stopper, and let stand 30 2 min. Dilute to the mark with KOH solution (100 g KOH, 200 mL water, and methanol to give a final volume of 1 L), stopper, and mix well. Read the absorbance at 480 nm of sample and blank versus water. Compare to a calibration curve prepared with dilute solutions of a suitable carbonyl compound (usually acetaldehyde in the 10-50 pg range). 

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