Abstract: The present invention provides a method of forming an ion of formula (I) comprising the steps of: (i) reacting a compound of the formula (IIa); with a biopolymer, BP, having at least one group capable of reacting with M to form a covalent linkage, to provide a biopolymer derivative of the formula (IIIa); and (ii) cleaving the C—X bond between X and the ?-carbon atom of the derivative of formula (IIIa) to form the ion of formula (I); where: (IV) is a carbon atom bearing a single positive charge or a single negative charge; and X is a group comprising a thioether sulphur atom bound directly to the ?-carbon which is capable of being cleaved from the ?-carbon atom to form an ion of formula (I). The biopolymer derivatives of the invention have enhanced ionisability with respect to free biopolymer (BP) enabling improved analysis of the biopolymer using mass spectrometry.

Abstract: The present invention provides a compound of formula (1): wherein: X is an electron-donating group, amino modifiers formed by reacting an amino alcohol with compounds of formula (1), amino-modified biomolecules formed by reacting said amino modifiers with a biomolecule and methods for producing the same.