Patent ID: 7494815

Claim:
A method for analyzing a compound with amino group comprising: (a) reacting a compound with amino group contained in a sample comprising the same with a derivatization reagent to generate a derivatized compound, wherein said derivatized compound is a compound of formula (I) or formula (II): wherein Ar 1 denotes an optionally substituted hydrocarbon or a substituent comprising a carbocyclic or heterocyclic ring having an aromaticity, wherein the binding of Ar 1 to the nitrogen atom may be (i) the binding of a carbon ring or heterocyclic ring having an aromaticity directly to the nitrogen atom, (ii) the binding via a carbonyl group or an amide group to nitrogen atom, or (iii) the nitrogen atom may compose a part of a carbon ring or heterocyclic ring, R 1 denotes a hydrogen atom, an optionally substituted alkyl group, or a ring forming carbon atom, and R 2 denotes an optionally substituted alkyl group, and wherein Ar 1 and R 1 or R 1 and R 2 may form a ring with each other, wherein Ar 2 denotes a carbocyclic compound residue or a heterocyclic compound residue having an aromaticity, X denotes an oxygen atom or a sulfur atom, Y denotes an oxygen atom, a sulfur atom, a secondary amine, a tertiary amine, or an optionally substituted methylene group, R 1 denotes a hydrogen atom, an optionally substituted alkyl group, or a ring forming carbon atom and R 2 denotes an optionally substituted alkyl group, and wherein R 1 and R 2 may form a ring with each other; (b) eluting said derivatized compound by liquid chromatography via stepwise elution on a concentration gradient; and (c) detecting said derivatized compound eluted from said liquid chromatography by mass spectrometry.