  Instead of the often used Foldy-Wouthuysen-Tani (FWT) transformation in
non-relativistic quantum chromodynamics (NRQCD), we take a more general
relation between the relativistic and non-relativistic on-shell spinors to
recalculate the quark-quark-gluon vertex for heavy quarks. In comparison with
the previous result using FWT, the recalculated coefficients in the NRQCD
Lagrangian are different at order $1/m^3$ and new at order $1/m^4$ and $1/m^5$,
where $m$ is the heavy quark mass.
