Analysis of aldehydes

We formally begin this chapter by asking you to read and analyze a Results section on your own. Excerpt 4A is a continuation of excerpt 3A (in chapter 3), regarding the analysis of aldehydes in aged beer. The excerpt includes most of the original text, but, to conserve space, only one figure (Figure 3) and one table (Table 2) are included. Note that the excerpt is a combined R D section. 

Calibration. Most aldehydes, except formaldehyde, form two geometrical isomers of the derivatives and appear as two peaks in the chromatogram. The sum of these two peak areas was used in the calibration measurements. A six-point calibration curve for nine carbonyl compounds was measured. The calibration range was 0.1-50 ppb, except for (E)-2-nonenal, where the calibration range was 0.01-5 ppb. The matrix used for calibration solutions was 5% ethanol solution, pH 4.5. Correlation coefficient (Rh values indicate that this method can be used for analysis of aldehydes in a wide range of concentrations (Table 1). 

To begin the analysis of the Discussion section, we ask you to read and analyze the Discussion section from the article on the analysis of aldehydes in beer. 

Analysis of Aldehydes in Beer Using Solid-Phase Microextraction with On-Fiber Derivatization and Gas Chromatography/Mass Spectrometry. 

Vesely, R Lusk, L. Basarova, G. Seabrooks,J. Ryder, D. Analysis of Aldehydes in Beer using Solid-Phase Microextraction with On-Fiber Derivatization and Gas Chromatography/ Mass Spectrometry. J. Agric. Food Chem. 2003, 51, 6941-6944. 

Igawa, M., J. W. Munger, and M. R. Hoffmann, Analysis of Aldehydes in Cloud- and Fogwater Samples by HPLC with a Postcolumn Reaction Detector, Environ. Sci. Technol, 23, 556-561 (1989). 

Braddock, R.J. and Kesterson, J.W. 1976. Quantitative analysis of aldehydes, esters, alcohols, and acids from citrus oils. J. Food Sci. 41 1007-1010. 

Mopper, K., Stahovec, W.L., and Johnson, L., Trace analysis of aldehydes by reversed-phase high-performance liquid chromatography and precolumn fluorigenic labeling with 5,5-dimethyl-l,3-cyclo-hexanedione, J. Chromatogr., 256, 243, 1983. 

Altshuller AP, McPherson SP. 1963. Spectrophotometric analysis of aldehydes in the Los Angeles atmosphere. J Air Pollut Control Fed 13 109-111. 

Analysis of aldehydic products of lipid peroxidation as 2,4-dinitrophenylhydrazone derivatives In order to enhance the detectability of saturated aliphatic carbonyls... 

Vesely, P., Lusk, L., Basarova, G., Seabrooks, J. and Ryder, D. (2003) Analysis of aldehydes in beer using solid-phase microextraction with on-fiber derivatization and gas chromatography/mass spectrometry,/. Agric. Food Chem., 51(24), 6941-6944. 

Kim N, Kratasyuk V. Luciferase biosensors for the analysis of aldehydes. In Jezowska-Trzebiatowska B, Kochel B, Slawinski J, Strek W (Eds) Biological luminescence. World Scientific, Singapore 1990 564-72. 

Nascimento, R.F., Marques, J.C., Lima Neto, B.S., De Keukeleire, D., and Franco, D.W. (1997). Qualitative and quantitative high-performance liquid chromatographic analysis of aldehydes in Brazilian sugar cane spirits and other distilled alcoholic beverages, /. Chromatogr. A, 782,13-23. 

For application to the analysis of aldehydes and ketones where the presence of NOx during gas-phase sampling may cause side-reactions with 2,4-dinitrophenylhydrazine to produce 5-nitrobenz-furazan-3-oxide by formation of the azide and elimination of N2 this has been obviated by use of the N-methyl compound (Buidt and Karst 1997). The analysis of 20-ketosteroids by a combination of pre- and postderivatization is described below. 

M2. Mann, B., and Greyeski, M. L., New chemiluminescent derivatizing agent for the analysis of aldehydes and ketones by high performance liquid chromatography with peroxyoxalate chemiluminescence. 7. Chromatog. 386, 149-158 (1987). 

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