Reactive molecules analysis procedure

This problem has been confirmed recently in a study of the mechanism of covalent reaction between nylon 6.6 and the sulpha toe thylsulphone dye Cl Reactive Blue 19 (7.37). Acid hydrolysis of the dyed fibre and HPLC analysis of the hydrolysate yielded the 6-aminohexylaminoethylsulphonyl derivative of Blue 19. Even when the dyeing procedure was optimised to achieve maximal exhaustion and fixation to the fibre [128], only about 30% of the N-terminal amino groups in the nylon 6.6 were accessible because of mutual blocking effects between these bulky anionic dye molecules. 

TMS production involves one specific functional group (-OH, -COOH, =NH, -NH2, or -SH), which loses an activated hydrogen and is replaced by a trimethylsilyl group (Proestos et ah, 2006). To achieve silylation, some authors have used BSTFA (N,0-hA(trimethyl-silyl)trifluoroacetamide) and TMCS (trimethylchlorosilane) successfully in several matrices (e.g. aromatic plants, cranberry fixiit) (Zuo et ah, 2002 Proestos et ah, 2006). Using silylated derivatives is advantageous for several reasons phenols and carboxylic acids are prone to silylation, these compounds can be derivatized in the same part of the process, and the minor products do not impede analysis and are well documented (Little, 1999 Stalikas, 2008). A two-step methylation procedure was used to analyze catechins and tannins in plant extracts. The first step used trimethylsilyl diazomethane (TMS-diazomethane) to pre-methylate the sample, and the second step used thermally assisted hydrolysis and methylation (THM). The pre-methylation step with TMS-diazomethane stabilized the dimer molecule m/z 540) by minimizing isomerization and reducing reactivity. (Shadkami et ah, 2009). 

Very Low Ptessore Pyroly (VLPP).— ety low pressure pyrolysis, introduced ten years ago, continues to inovide many data on unimolecular reactions. Tbe method has been reviewed. The reactive gas is heated in a Knudsen cell to a desired temperature. The pressure is kept sufficiently low for activation to ocoir almost exclusively by collisions with the wall. Sometimes, however, radicaiHradical reactions are also important, and even essential. Mass spec ometric analysis allows for a sensitive detection of all reaction products. An important point is that the collision freqixncy correspondii to Z [M] in equation (29) for collisional activation with gas molecules can be varied only to a very limited extent. It is usually about 10 s. Thus it is not possible to study by VLPP the equivalent to the pressure dependence of a unimolecular reaction. The usual procedure for obtaining Arrhenius parameters in the high-pressure limit has been dien to fit the measured temperature dependence by an RRKM caloilation. The Arrhenius... 

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