Application of BSA-modified silica for solid phase extraction of progesterone from river water samples

• Novel BSA–silica sorbent enables sensitive SPE of progesterone in water. • SPE–HPLC-DAD provides 250 × enrichment with 94–104% recovery. • Method validated in Danube water with high selectivity for progesterone. • Sorbents remain highly efficient with <3% loss after 4 years of storage. This study reports the development and application of bovine serum albumin (BSA)-modified silica gels as selective and durable sorbents for the solid-phase extraction (SPE) of progesterone from river water samples. One of the sorbents was used for SPE preconcentration followed by progesterone quantification in a sample collected from the Danube River. The standard addition method followed by high-performance liquid chromatography (HPLC-DAD) detection enabled the quantification of progesterone at a concentration of 143.0 ± 4.0 ng/L. At elevated progesterone concentrations (1.0 to 2.0 × 10 -7 M), recoveries approached 100 %, demonstrating the high efficiency of the developed extraction sorbents. The overall method recovery ranged from 91.4 to 101.0 %, confirming the method’s accuracy and robustness. Furthermore, under optimized SPE conditions, developed sorbents were highly selective towards progesterone compared to other reproductive hormones. The sorbents exhibited excellent long-term stability, with no significant change in binding efficiency observed over a four-year period (variation lower than 3 %), maintaining consistent recoveries of 94–96 %. Newly developed BSA-modified silica sorbents represent a promising tool for trace analysis of steroid hormones, as well as for their routine environmental monitoring.