Volatile aldehydes analytical method

It becomes clear that analytical methods based on the evaluation of the end products of deteriorative reactions will not be satisfactory. Therefore in our own experiments amino acid analysis of Amadori compounds and gas chromatography of volatile Strecker aldehydes were applied to detect the onset of the Maillard reaction well before detrimental sensory changes occurred. 

There are 14 analytical methods developed by U.S. EPA for measuring common organic pollutants in air. These analytes include aldehydes and ketones, chlorinated pesticides, polynuclear aromatic hydrocarbons, and many volatile organic compounds. These methods may also be applied to analyze other similar substances. All these methods are numbered from TO-1 to TO-14 and based on GC, GC/MS, and HPLC analytical techniques. Method numbers, sampling and analytical techniques, and the types of pollutants are outlined in Table 1, while individual substances are listed in Table 2. 

Analytical characteristics, tandem mass spectrometry, 127-29 Analytical method, volatile aldehydes, 61-77 Apple essence... 

With improved analytical methods there has been a large increase in the number of compounds identified in wines. Volatile compounds from different families (such as alcohols, esters, aldehydes, terpenes, etc.) play an important role in the organoleptic characteristics of wines. This wide variety of compwimds with different chemical properties and with different concentrations makes the flavour pa-ofile of wines very complex. Therefore, it is necessary to standardise the terminology so as to facilitate the knowledge of the aromatic profile of wines. 

You should already be familiar with approximately half of the reactions listed in Table 7.2 from your introductory class. Moreover, if you have taken or are taking a classical analytical laboratory course, you have possibly tried or are trying to prepare an oxime, a phenylhydrazone, a 2,4-dinitrophenylhydrazone, or a semicarbazone. These compounds serve as crystalline derivatives with sharp and characteristic melting points for identifying aldehydes and ketones and for distinguishing them. When spectroscopic methods for structure elucidation are not available, carbonyl compounds are more difficult to characterize unambiguously because of their volatility. 

As has been previously said, 2,3-butanodione (diacetyl) is an important aroma of alcoholic beverages, it has not been studied and measured extensively in the past because of analytical difficulties in the quantitation caused by its highly volatile nature, chemical instability, and interference of other compounds. Colorimetric methods to measure diacetyl have been widely used in the past. These methods involve steam distillation to isolate diacetyl from the matrix. However, distillation has the disadvantage of incomplete isolation of diacetyl from other closely related compounds that will result in an overestimation of its concentration. A fluorometric method was developed to improve upon the lengthy distillation methods that involve derivatization. Although acetaldehyde and its acetal can be determined by direct injection GC-FID in spirit drinks (EU reference method for spirits), most chromatographic methods for minor aldehydes implicate also derivatization. While a very sensitive and accurate method based on SMPE without derivatization and MS detection has been developed, it requires the use of... 

METHOD b SOLVENT- AND CATALYST-FREE To a 50-mL, two-ncckcd, round-bottom flask flushed with Ar and equipped with a magnetic stirring bar and a reflux condenser were added 1,3-dicarbonyl compound 79 (1.28 mmol), aldehyde 78 (1.5 mmol), and diamine 77 (1.28 mmol). The mixture was stirred at 120 °C under Ar for 4 h, diluted with EtOAc (20 mL) after cooling, and Altered through a short pad of Celite. Evaporation of the volatiles afforded a crude slurry. An analytical sample was obtained by flash chromatography over silica gel. 

---