Analyzing Bisphenol Analogues with UHPLC–MS/MS

In a recent study out of the Tianjin Centers for Disease Control and Prevention in Tianjin, China, scientists used ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC–MS/MS) and high-throughput solid-phase extraction (SPE) to determine bisphenol analogues (BPs) in human urine. Their findings were published in the Journal of Chromatography A (1).

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Bisphenol analogues (BPs) are a type of typical environmental endocrine-disrupting chemicals (EDCs). Bisphenol A (BPA) is a chemical made in large quantities, mainly for use in the production of polycarbonate plastics (2). It can be found in various products, such as shatterproof windows, eyewear, water bottles, and epoxy resins that coat some metal food cans, bottle tops, and water supply pipes. It can enter the human body in various ways, but mostly through diet, with BPA in food and beverages accounting for most daily human exposure. Other BPs, such as including bisphenol F (BPF) and bisphenol S (BPS), have emerged as substitutes for polycarbonate resins. Because of their widespread use in food industry, BPs have been detected in soil, air, drinking water, cosmetics, food and biological samples worldwide.

In various studies, a link has been found between BP exposure, and an elevated risk of cardiovascular diseases, neurological disorders, reproductive abnormalities, obesity, and diabetes. Further, BPs can impact the neurodevelopment of infants and prepubertal children and are also believed to be involved in the development of diseases like prostate and breast cancer. After entering the human body, BPs undergo rapid absorption and subsequent metabolism by the liver and kidneys. Urine is the primary route for BP excretion; subsequently, quantifying BP levels in urine helps to understand BP exposure levels in the human body. Establishing a sensitive, accurate, and precise method is essential for monitoring and assessing the internal exposure to BPs in the environment.

In this study, the scientists aimed to establish a highly sensitive and high-throughput method of identifying and quantitatively analyzing nine BPs in human urine. This was done utilizing 96-well solid-phase extraction (96-well SPE) in conjunction with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) employing multiple reaction monitoring (MRM), information-dependent acquisition (IDA), and enhanced product ion (EPI) scan modes. Urine samples were initially thawed to room temperature, followed by digestion using β-glucuronidase in an ammonium acetate buffer solution at 37 °C overnight. Subsequently, they were purified using 96-well SPE and finally analyzed by UHPLC-MS/MS.

The limits of detection (LOD) for the nine BPs ranged from 0.05 μg∙kg⁻¹ to 0.3 μg kg⁻¹. Average recoveries fell within the range of 92.8% to 111.7%. Moreover, both the intra-day and inter-day precisions were satisfactory, with relative standard deviations (RSDs) ranging from 2.2% to 6.7% and 3.5% to 6.3%, respectively. The targets in the samples exhibited a perfect match, with a purity fit value exceeding 70% from the self-built library. While the MRM scan mode ensured quantitative accuracy, the comparison of the obtained secondary mass spectra with the standard library in the EPI scan mode strengthened the qualitative function of the nine BPs and reduced the likelihood of false positives in the detection of the nine BPs in urine samples.

References

(1) Jin, W.; Yang, S.; Yin, L.; et al. Determination of Nine Bisphenol Analogues in Human Urine by High-Throughput Solid-Phase Extraction and Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry Analysis. J. Chromatogr. A 2024, 1730, 465096. DOI: 10.1016/j.chroma.2024.465096

(2) Bisphenol A (BPA). National Institute of Environmental Health Sciences 2024. https://www.niehs.nih.gov/health/topics/agents/sya-bpa (accessed 2024-7-29)