Development and application of an LC-MS/MS method for the determination of paraquat and diquat in the urine of rural workers aiming at the evaluation of occupational exposure

• Grant number: 25/12187-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2025
• End date: August 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Analytical Chemistry
• Principal Investigator: Alvaro José dos Santos Neto
• Grantee: Ana Carolina Paschoarelli do Nascimento
• Host Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

The significance of Brazil's agricultural sector is indisputable, given its capacity to supply both domestic demands and a substantial share of the international market. In the pursuit of high productivity, Brazilian producers not only implement numerous technological advancements but also make extensive use of agrochemicals. However, the widespread application of these substances can pose serious risks to human health and the environment. In this context, paraquat, a non-selective, fast-acting contact herbicide was employed for decades until its ban in Brazil in 2020 and several other countries, due to its high intoxication and lethality. Following this prohibition, diquat emerged as a prominent alternative; nevertheless, it also exhibits significant intoxication concerns. Consequently, the monitoring of these herbicides' use is essential to ensure both occupational safety for agricultural workers and food security. One of the most effective approaches for assessing occupational exposure to these active compounds involves their determination in urine samples, as both paraquat and diquat, herbicides belonging to the quaternary ammonium class, are polar, readily excreted compounds amenable to analysis via non-invasive and rapid biological sample collection. Accordingly, the primary objective of this study is to develop and validate an analytical method based on liquid chromatography coupled with tandem mass spectrometry for the quantification of paraquat and diquat in the urine of agricultural workers. This methodology aims to enhance the understanding of occupational exposure levels and contribute to future investigations on health risks and public health surveillance.