Ex vivo SPME-LC-MS/MS determination of carbamazepine in tissues of Arctic marine bivalve Chlamys islandica.

The Solid-Phase Microextraction (SPME) is a minimally invasive extraction technique that has gained interest in environmental studies. In this paper, we developed an SPME-LC-MS/MS protocol under ex vivo conditions to extract carbamazepine (CBZ) and its main metabolite, carbamazepine-10,11-epoxide (CBZE) from Chlamys islandica solid tissues. Optimization of SPME included selection of the stationary phase, desorption solution, desorption and extraction times. Under optimized conditions, we utilized commercially available C18 fibers, a 10 min static extraction and a 10 min desorption of CBZ and CBZE performed into 50 μL of ACN:H2O (80:20, v/v) mixture. The linear range for CBZ was 2.5-20 ng g-1 of wet mass with R2 = 0.9900; for CBZE, the linear range was 20-1000 ng g-1 of wet mass (R2 = 0.9743). LLOQ levels were 2.5 ng g-1 and 20 ng g-1 of wet mass for CBZ and CBZE, respectively. A 7-day exposure experiment was performed as a proof-of-concept, in which bivalves were exposed to CBZ at 1000 ng L-1. Ex vivo SPME enabled CBZ quantification in all four tissues. Mean concentrations increased from day 1 to day 7 in muscle, gonads, and the digestive system, while remaining stable in gills. Similar temporal trends were observed using solid-liquid extraction (SLE), although lower concentrations were obtained. The results demonstrate that SPME enables rapid and minimally invasive determination of pharmaceuticals in marine organisms and represents a promising approach for future in vivo monitoring of contaminant bioaccumulation.