Carbonyl compounds, detection identification

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). 

Ethanol and a long list of carbonyl compounds and aliphatic acids occur in fresh milk (Table 1.5). Some of them have been detected in only a few of the samples in which they were sought. Techniques for detecting such compounds include derivatization with 2,4-dinitrophe-nylhydrazine and various methods of volatilization, extraction, and chromatography (Harper and Huber 1956 Morr et al. 1957 Harper et al. 1961 Wong and Patton 1962 Scanlan et al. 1968 Marsili et al. 1981). The sum of the concentrations of acids listed in Table 1.5 is only 1-3 mmol/liter, compared to the citrate concentration of 10 mmol/liter. Oxalate has been reported to occur in milk (Zarembski and Hodgkin-son 1962) on the basis of a certain colorimetric reaction, but positive identification has not been made. 

Carbonyl compounds condense with arylhydrazines with the formation of crystalline arylhydrazones, mostly not very soluble. The reaction is used both for the detection and the identification of carbonyl compounds. 

Trimethylsilyl derivatives of ten hydroxy- and methoxyhydroxyflavonoids have been studied by the GC-FTIR technique." " The correlation found between retention and gas-phase IR data was used in structural identification of compounds having very similar chromatographic behavior. The shift of the carbonyl frequency gave information on the presence of substitution. Some hydroxy- and methoxy-substituted flavones have been studied following carbon dioxide supercritical fluid chromatography on polymethylsiloxane capillary columns using flame ionization and FTIR detection." " " ... 

The infrared spectrum of erythromycin estolate is the most commonly accepted method for compound identification. The spectrum of a 10 mg/ml chloroform solution of erythromycin estolate from 850-4000 cm--1- is shown in Figure 1, The most characteristic difference between the infrared spectra of erythromycin base and estolate and that of anhydroerythromycin is that the latter is lacking the keto-carbonyl band at 1685 cm l (5.93 u). If a sample of erythromycin base or estolate contains at least 5 percent anhydroerythromycin, a decrease in the intensity at 1685 cm l should be observed. This decrease can most readily be detected by measuring the ratio of the absorbance at 1685 crn" -(5.93 U) to that of the ester absorbance at 1735 cm l (5.76 u). The amount of water in the sample can also be evaluated by the band at 1610 cm-1 (6.2 u). ... 

From 1966 through 1974 several notable studies were conducted on 5-containing compounds in tobacco smoke. In 1966, Philippe (2940) reported on the identification of thiocyanogen, thiocyanic acid, hydrogen sulfide, carbonyl sulfide, methylthionitrite, dimethyl sulfide, carbon disulfide, and thiophene in MSS. In that same year, ethyl mercaptan was qualitatively detected by Grob (1419). 

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