In this work, a new purpose-made portable CE instrument with a contactless conductivity detector was used for the determination of degradation products of nitrogen mustards in different water samples. The capillary was coated with poly(1-vinylpyrrolidone-co-2-dimethylaminoethyl methacrylate) to avoid analyte-wall interactions. The coating procedure was studied to obtain the best repeatability of the migration time of the analytes. Four different coating procedures were compared; flushing the capillary with the copolymer at 100 psi for 2 min at 60 degrees C provided the best RSD values (<4%). The analytical method was also optimized. The use of 20 mM of MES adjusted to pH 6.0 with His as running buffer allowed a good baseline separation of the three analytes in different water samples without matrix interferences. The method permitted the detection of the three degradation products down to 5 M.