  We introduce the notion of pure Q-solvable algebra. The quantum matrices,
quantum Weyl algebra, U_q(n) are the examples. It is proved that the skew field
of fractions of pure Q-solvable algebra is isomorphic to the skew field of
twisted rational functions. This is the quantum version of Gelfand-Kirillov
conjecture for solvable algebraic Lie algebras.
