Applying chemical metrology to overcome challenges in the analysis of perchlorates in food and water

Abstract

Safe food and water are essential for public health and economic well-being, particularly as new pollutants emerge. Among these are inorganic contaminants, including arsenic, mercury, chromium VI, cadmium, lead, selenium, fluoride, nitrate, nitrite, aluminium, and perchlorates (Sellers et al., 2007; Dasgupta et al., 2005; WHO, 2011; Ginsberg et al., 2007). This study focuses on the measurement and metrological challenges associated with perchlorates in food and water. Perchlorate, a negatively charged molecule consisting of one chlorine atom and four oxygen atoms, can occur naturally or be man-made. It also forms naturally in the atmosphere and contaminates drinking water and food through agricultural runoff, groundwater leaching, and irrigation. Once introduced into the environment, perchlorate accumulates in crops and water. Exposure disrupts thyroid function by inhibiting iodine uptake, impairing hormone production, and causing developmental issues in fetuses, cognitive deficits in children, and metabolic disorders in adults. Chronic exposure may also increase cardiovascular health risks. ISO 19340 outlines the determination of perchlorate in water using ion chromatography with conductivity detection. However, there is no standard method for analyzing perchlorates in food, despite its significant health implications. Perchlorate is typically reported in micrograms per litre (µg/L) in water or micrograms per kilogram (µg/kg) in food. Metrological challenges in measuring perchlorates are observed at ultra-low concentrations at Kenya Bureau of Standards (KEBS). These challenges include matrix interferences, method sensitivity, lack of calibration standards and partially validated method affecting accuracy and traceability of the perchlorate result. Locally, there are no certified reference materials (CRMs) or proficiency testing (PT) schemes for perchlorate analysis. Importation of CRMs and participation in PT schemes is costly, and available CRMs are primarily in aqueous media, which do not address the analytical complexities of food matrices. Moreover, there are no established local standards or maximum allowable limits for perchlorate in food and water, leaving significant data gaps on local contamination levels. KEBS Inorganic Chemistry Laboratory is working to bridge these gaps by investing in ion chromatography equipment with low detection limits, collaborating with regional metrology institutes to develop region-specific CRMs and PT schemes and capacity building to enhance analytical capability for perchlorate measurement in both food and water. Future metrological research should prioritize perchlorate and other emerging contaminants to address analytical challenges, develop calibration standards and PT schemes, particularly for food matrices. Enhanced metrology systems will strengthen public health initiatives, bolster international trade, and contribute to Sustainable Development Goals (SDGs) related to clean water (SDG 6), good health and well being (SDG 3) and food security (SDG 2). Improved analytical capabilities will produce traceable, reproducible, and internationally comparable results, fostering confidence in Kenya’s environmental monitoring programs. The data generated will enable policymakers to implement targeted mitigation strategies, promoting sustainable industrial and agricultural practices.