Desenvolvimento e validação de métodos para análise de clorato em água de processo e suco de acerola por cromatografia de íons

Abstract

Brazil, as a major producer and exporter of fruits, including acerola, must meet international standards to remain competitive in the global market. These food products are often contaminated by chlorinated substances (DBPs) present in treated water, associated with the use of chlorine-based sanitisers. In fruits and vegetables, among the chlorinated inorganic contaminants, chlorate (ClO3⁻) stands out, which has aroused increasing concern among health and food safety authorities such as WHO, EFSA, and EPA. Considering that exposure to this substance occurs predominantly through the ingestion of contaminated water and food, international regulatory bodies have established maximum chlorate limits for the marketing of these products. Thus, the identification and quantification of this anion are essential to ensure food safety and public health. Since export specifications for fruit and its products allow for very low chlorate concentrations (MRL of 0.05 mg/kg for citrus), sensitive and selective analytical methods become indispensable for monitoring in the agro-industry. Ion chromatography (IC) stands out as a regulated technique for the determination of ClO3⁻, offering high selectivity, rapid result acquisition, the ability to detect multiple ionic species, and low cost compared to LC-MS. In 2024, fifty years after the first survey on DBPs, chlorate was reaffirmed as a target analyte in several methods published by the USEPA. Aiming to contribute to advances in chlorate determination, this work reports the development of two methods for chlorate quantification, one in process water and the other in acerola juice. For water analysis, a more sensitive method than direct injection was developed, using solid-phase extraction coupled with ion chromatography in conductimetric detection (SPE-IC-DC), through factorial design to optimize the extraction conditions. The method showed selectivity, absence of matrix effect, and detection and quantification limits of 0.2 and 0.6 µg/L, respectively. A method based on liquid-liquid extraction combined with solid-phase extraction and ion chromatography (LLE-SPE-IC) was also developed for the analysis of concentrated acerola juice, obtaining a quantification limit three times lower (18 µg/Kg) than the European limit. Thus, the SPE-IC-DC and LLE-SPE-IC methods proved to be viable and efficient for quality control in juice processing industries.