An electrodialysis method and apparatus are provided for treating a sample including trace metals in a matrix. Advantageously, the present invention allows for highly accurate detection of trace contaminants in a solution sample, in particular trace metals, substantially in real-time and on-line. The present invention includes flowing a carrier solution through a carrier solution channel separated from a sample channel by a membrane. A component of the carrier solution is diffused through the membrane into the sample channel to stabilize trace metals in the solution sample for subsequent analysis. Simultaneously, the matrix is eliminated, neutralized, and/or modified for enhanced analysis.