Testing sample stability in short-term isochronous stability studies for EU-wide monitoring surveys of polar organic contaminants in water

The article introduces the European Union (EU)-wide monitoring concept as run by the European Commission’s Joint Research Centre (JRC) and specifically addresses the issue of stability tests for environmental specimen and samples using the so-called isochronous stability-test design. We briefly describe the underlying statistical concept and apply it to water samples being collected in the context of the JRC’s EU-wide environmental monitoring activities.The stability of spiked tap-water and river-water samples and their containers was assessed at 4°C, 20°C and 40°C using ibuprofen, gemfibrozil, ketoprofen, diclofenac, bezafibrate, naproxen, perfluoroheptanoate (PFHpA), perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), carbamzepine, sulfamethoxazole, terbutylazine and triclosan as test substances in two different stability-testing schemes.The stability of the samples decreased as expected with an increase in the storage temperature. Uncertainty contributions were calculated and it was concluded that this type of sample remains stable for ca. 6 weeks if stored at 4°C.

► We developed a non-probabilistic, pan-European snapshot mechanism for water samples.
► It is used to derive benchmarks and links to regional chemical-monitoring programs.
► We addressed the issue of analyte stability in water samples.
► We applied the isochronous stability test used for reference materials.
► We used data directly to feed into policy implementation.