Chemical methods, determining formaldehyde

The various components and raw materials of the resins can be determined using different chemical methods (Table 19). The content of total formaldehyde is accessible by hydrolysis of an aminoplastic resin this process, however, is not possible for PF resins. Urea can be determined in the easiest way from the resin nitrogen content. However, other possible... 

Therefore, the aim of our study was to clarify the mechanism of alkenes and FO interaction using quantum chemical methods. Thereto we determined thermod5mamic parameters of the reactions (A and found the key intermediates and transition states of the corresponding transformations and considered characteristics of their structure depending on the alkene structure involved in the reaction. The following alkenes were used as model compounds ethylene, propylene, butene-1, isobutylene and t-butene-2. A formaldehyde dimer (FD) served an example for FO calculation. 

Wet-chemical analysis and optical methods have been used to determine the abundance of formaldehyde in ambient air. Table 4-9 shows mixing ratios observed at various locations. The highest values are associated with urban air, especially under conditions of photochemical smog. Maximum values may then reach 70-100 ppbv. Mixing ratios in rural areas are of the order of a few ppbv, and still lower values are found in marine air masses. 

Several methods have been developed for assaying non-enzymatic glycosylation. As far as biological systems are concerned, these have been extensively reviewed by A. J. Furth in 1988 (5). They include both assays on intact proteins after chemical degradation and selective detection of e.g. 5-hydroxymethylfurfural (HMF) and formaldehyde using the thiobarbituric assay (TEA), and assays on protein hydrolysates with or without previous reduction of the protein-bound Amadori compound. In this last case, the analysis is based on the determination of furosine which is specifically formed from lysine Amadori compounds with a yield of approximately 30% (6). The furosine method, originally developed for milk (7), has been the subject of several analytical improvements both for food products (8) and biological materials (9). More recently, another method has been proposed to evaluate the extent of early Maillard reaction in milk products. This method is based on direct measurement of the Amadori product lactuloselysine which is released after complete enzymatic hydrolysis (10). 

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