  We perform calculations of the dependence of nuclear magnetic moments on
quark masses and obtain limits on the variation of the ratio of quark mass and
strong interaction scale (m_q/Lambda_{QCD}) from recent atomic clock
experiments with hyperfine transitions in H, Rb, Cs, Yb+, Hg+ and optical
transition in Hg+. Experiments with Cd+, deuterium/hydrogen, molecule SF_6,
  Zeeman transitions in He_3/Xe are also discussed.
