Derivatization with alkali methylate

The derivatization of aldehydes in reducing carbohydrates can also be performed by a condensation reaction between the active hydrogens of l-phenyl-3-methyl-5-pyrazolone (PMP) and the aldehyde functionality under slightly basic condition. The formed bis-PMP derivatives can be separated by CZE and detected by UV absorbance. Oligosaccharides can also be separated as complexes with a variety of compounds, including acetate, molybdate, germanate, stannate, arsenite, wolfra-mate, vanadate, and tellurate of various alkali and alkaline... 

The silver or alkali salts of MO-dibenzoyl derivatives are alkylated at oxygen 0-benzyl benzohydroxamate is derivatized at nitrogen in the presence of NaOMe (119). It is of interest to note that lengthening of the chain in the alkyl-ator leads to a gradual increase in 0-alkylation Mel (100 N), EtI (100 N), n-Prl (75 N, 25 O), -BuI (70 N, 30 O). Exclusive N-methylation also occurs with Mel, but the 0-methyl derivative is evident when Me2S04 is used. Diazomethane effects 0-methylation of 0-alkyl hydroxamates (120). 

Derivatization by permethylation has been shown beneficial for the desorption efficiency and stability of the sialic acid(s) attached [84] however, the permethylation reaction requires strong alkali conditions, which may destroy the alkaline-labile substituents (such as 0-acetyl groups) that may be present as substituents. In order for the selective methylation of sialic acid carboxyl group to achieve a better stability, the same parameters are valid as were presented for glycans (see Section 6.2.5). The coupling of nano-HPLC with MALDI-MS requires a fraction collection step, in order to deposit the separated components arising from the... 

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