  A mathematical model describing a steady pH-gradient in the solution of
ampholytes in water has been studied with the use of analytical, asymptotic,
and numerical methods. We show that at the large values of an electric current
a concentration distribution takes the form of a piecewise constant function
that is drastically different from a classical Gaussian form. The correspondent
pH-gradient takes a stepwise form, instead of being a linear function. A
discovered anomalous pH-gradient can crucially affect the understanding of an
isoelectric focusing process.
