Bonding agent moisture-sensitive

It is most desirable that a given amino acid should form a single-derivative peak after treatment with a single derivatization agent. Unfortunately, that is not the case for many important determinations. Thus, for example, permethylation [481] and the formation of W-dimethylaminomethylene alkyl esters [482] appeared limited to only some amino acids. Persilylation of all amino acid functional groups with potent silyl donors [483] comes perhaps closest to definition of a universal reaction , but even here some problems are encountered (a) derivatization can be time-consuming (b) multiple derivatives are occasionally formed even under precautions (c) Si-N bonds are moisture-sensitive and (d) truly quantitative derivatization is difficult to achieve for all protein amino acids. 

Proprietary bonding agents are used almost exclusively in modern manufacturing processes for metal-rubber bonded products. Isocyanates were proved to be of value in the immediate postwar period, but their moisture sensitivity and tendency to be wiped off the metal during processing have proved as disadvantages. The majority of commercially available adhesives in use today are a complex mixture of undisclosed composition, and in many instances are specifically used for particular rubbers and substrates. 

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