High-throughput and sensitive determination of urinary zearalenone and metabolites by UPLC-MS/MS and its application to a human exposure study

Biomarker-based strategies to assess human exposure to mycotoxins have gained increased acceptance in recent years. In this study, an improved method based on UPLC-MS/MS following 96-well μElution solid-phase extraction was developed and validated for the sensitive and high-throughput determination of zearalenone (ZEN) and its five metabolites α-zearalenol (α-ZEL), β-zearalenol (β-ZEL), α-zearalanol (α-ZAL), β-zearalanol (β-ZAL), and zearalanone (ZAN) in human urine samples, using 13C-ZEN as an internal standard for accurate quantification. Two plates of samples (n = 192) could be processed within 2 h, and baseline separation of all the analytes was achieved in a total runtime of 6 min. The proposed method allowed ZEN and its metabolites to be sensitively determined in a high-throughput way for the first time, and with significantly improved efficiency and accuracy with respect to existing methods. The limits of detection (LODs) and limits of quantitation (LOQs) ranged from 0.02 to 0.06 ng mL−1 and from 0.05 to 0.2 ng mL−1, respectively. The recoveries for the spiked samples were from 87.9 to 100%, with relative standard deviations (RSDs) of less than 7%. 301 urine samples collected from healthy volunteers aged 0–84 years in China were analyzed with and without enzyme hydrolysis to determine total and free ZEN biomarkers, respectively. ZEN, ZAN, α-ZEL, and β-ZEL were detected in 71.4% of the samples at levels of 0.02–3.7 ng mL−1 after enzyme hydrolysis. The estimated mean probable daily intake (PDI) was much lower than the tolerable daily intake (TDI). Adolescents had higher exposure than children, adults, and the elderly.