This document specifies two methods for the determination of co-monomer contents of polyethylene products by solution state 13C-NMR spectrometry (nuclear magnetic resonance spectrometry): — Method A: inverse gated decoupling method; — Method B: insensitive nuclei enhanced by polarization transfer method. This document is applicable to copolymers of ethylene having a content of other 1-olefinic monomers of less than a mass fraction of 50 %. This document is not applicable to ethylene homopolymers or copolymers in which ethylene is polymerized with two or more type 1-olefin comonomers.