Optimization of matrix solid-phase dispersion coupled with high performance liquid chromatography for determination of selected antibiotics in municipal sewage sludge
Two alternative matrix nano-solid phase dispersion approaches coupled with HPLC-DAD were developed for the determination of sulfadiazine, sulfamerazine and sulfamethoxazole in STP sludge samples. 0.2 g portions of the sludge sample were mixed with MWCNT–silica, and/or nano-silica–C18 as dispersant–sorbent materials and then extracted with appropriate solvents. Two series of 24−1 fractional factorial designs were assigned to study the most important experimental variables, weight and composition of the dispersing materials and type and volume of the elution solvent, and also to help find the optimized operational conditions. Among these, the set based on carbon nanotubes showed more acceptable results regarding the clean-up and final extract solution quality. The selected approach showed good sensitivity for the analytes with LOD values of 3.1–4.0 ng g−1. It also produced linear responses over a range of three orders of magnitude (up to 4000 ng g−1). The precision of the method was estimated for inter- and intra-day replicates at various concentrations and RSD values of less than 9.5% were achieved.