Looking at previous question, I begun to think and came upon the following more solid question: Let $SU_q(N)$ be the usual quantized coordinated algebra of $SU(N)$. Now consider, for some fixed value of $q$, the element $$ v := \sum_{i=1}^k \lambda^i(q) v_i \in SU_q(N), $$ where each $\lambda^i(q)$ is some polynomial function in $q$, and each $v_i$ is a product of some subset of the generators of $SU_q(N)$. It has the obvious corresponding element in ${\cal O}(SU(N))$: $$ v' := \sum_{i=1}^k \lambda^i(1) v_i.$$ It seems to be for me obvious that if $v =0$, then we must necessarily to have $v' = 0$. However, I can't see how to prove this with care?