In this episode of Concentrating on Chromatography, David speaks with Francis Femi Oloy about using chromatography to uncover hidden pollutants in real-world water systems.Femi’s team analyzed polychlorinated biphenyls (PCBs) in six major rivers in southwestern Nigeria — compounds that were banned decades ago but still persist in the environment. Using a workflow that many analytical labs will recognize — liquid–liquid extraction, cleanup, rotary evaporation, nitrogen blowdown, and GC-ECD detection — they quantified 25 PCB congeners at trace levels and linked the results to ecological and human health risk.📌 In this conversation, we cover:• Why legacy pollutants like PCBs still show up today• Choosing GC-ECD vs LC-MS for halogenated compounds• Liquid–liquid extraction and matrix cleanup strategies• Why sample concentration is critical for dilute environmental samples• How rotovap + nitrogen blowdown work together without losing volatile analytes• Seasonal trends (why wet season levels were higher)• Translating concentration data into meaningful risk assessmentsThis episode is perfect for anyone working in:Chromatography • Environmental analysis • Sample prep • Trace analysis • GC methods • Analytical chemistryIf you enjoy practical discussions about real laboratory workflows and how chromatography solves real problems, subscribe to Concentrating on Chromatography. 🔬 Paper discussed: Polychlorinated biphenyls (PCBs) in rivers of Southwestern Nigeria: sources, seasonal distribution, and assessment of human health risks# 🔔 More episodesSubscribe for more interviews with scientists using chromatography and mass spectrometry to solve real-world challenges.