  Suppose $I$ is an ideal of a polynomial ring over a field, $I\subseteq
k[x_1,\ldots,x_n]$, and whenever $fg\in I$ with degree $\leq b$, then either
$f\in I$ or $g\in I$. When $b$ is sufficiently large, it follows that $I$ is
prime. Schmidt-G\"ottsch proved that "sufficiently large" can be taken to be a
polynomial in the degree of generators of $I$ (with the degree of this
polynomial depending on $n$). However Schmidt-G\"ottsch used model-theoretic
methods to show this, and did not give any indication of how large the degree
of this polynomial is. In this paper we obtain an explicit bound on $b$,
polynomial in the degree of the generators of $I$. We also give a similar bound
for detecting maximal ideals in $k[x_1,\ldots,x_n]$.
