▎ 摘　　要

NOVELTY - Double heteroatom doped porous graphene-type carbon nanosheet is claimed. The graphene-type carbon nanosheet is composed of three-dimensional graphene sheet-type carbon nanosheets, thickness of the carbon nanosheet is 2-50 nm, the specific surface area is 500-750 m2/g, and the pore size distribution is 0.1-2 nm, 2-50 nm and 50-100 nm and double heteroatom includes sulfur and nitrogen atoms. USE - The carbon nanosheet is useful for analysis and quantitative detection of different types of amino acid biomolecules. ADVANTAGE - The nanosheet: has low background interference peaks and high ionic strength. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing the double heteroatom-doped porous graphene carbon nanosheet comprising comprising (i) combining thiourea, citric acid and/or sodium citrate under room temperature and stirring conditions, adding the sodium chloride to the secondary water separately until completely dissolving, freezing the obtained mixed solution under liquid nitrogen, placing it in a freeze dryer for drying, and (ii) placing the resultant solid powder in an argon atmosphere at high temperature for carbonization, washing with secondary water and drying; and #Use of double heteroatom doped porous graphene-type carbon nanosheets comprising detecting small molecular weight compounds by inter-mass spectrometry using matrix-assisted laser desorption/ionization matrix material during matrix-assisted laser desorption ionization flight process, where small molecular weight of compound is compound with m/z less than 1000