This application note investigates the presence of trace hormone contaminants in tap water and their impact on LC-MS/MS analyses. Samples collected from laboratories revealed detectable levels of hormones such as estradiol, androsterone, and corticosterone. Using advanced LC-MS/MS methods, the study demonstrates that these contaminants, even at low concentrations, can interfere with sensitive analytical results. Learn how purification with Milli‑Q® water systems—combining reverse osmosis, EDI, and UV—effectively removes these contaminants, producing ultrapure water free of detectable hormones. The study underscores the importance of high‑quality water to ensure reliable, reproducible results in trace-level LC‑MS/MS applications.