<p>Water disinfection processes are essential to ensure safety and quality for consumption, but are often associated with the formation of Disinfection Byproducts (DBPs), such as ClO₃⁻, which are harmful and can impact the quality of water used in food processing. The presence of DBPs in water at levels above those permitted by government agencies can cause diarrhea and even death. In this context, the development of sensitive methods to control ClO₃⁻ levels in water, such as those used in food processing, is essential. The ion chromatography (IC) is a powerful tool for determining DBPs and is reported in standard methods by the United States Environmental Protection Agency (U.S. EPA) to quantify these compounds in water. Thus, a new method based on SPE-IC-DC was developed to control ClO₃⁻ levels in water used in food processing. A factorial study was used to optimize the SPE conditions, the chromatographic conditions were adjusted, and the method was validated. The method showed good selectivity and absence of matrix effect. The detection limit by SPE-IC was approximately 200 times lower (0.2&#xa0;μg/L) when compared to the direct method, while the quantification limit was approximately 166 times lower (0.6&#xa0;μg/L). The method was able to quantify ClO₃⁻ in the samples at concentrations of 1.6 to 5.0&#xa0;μg/L with adequate precision and accuracy. The results of the analysis of water samples from industrial juice processes indicated acceptable amounts of ClO₃⁻. The determination of ClO₃⁻ by SPE-IC was efficient, inexpensive, and showed higher sensitivity, which makes it promising for use in quality control in waters used in food industries.</p>