One step derivatization and switchable hydrophilicity solvent-based microextraction for the determination of adamantane analogues in human urine by HPLC-FLD

The present study describes an “one-step” derivatization and microextraction using a pH-switchable hydrophilicity solvent for the determination of amantadine and memantine in human urine by liquid chromatography and fluorescence detection. The procedure is based on the derivatization of the analytes with o-phthalaldehyde/N-acetyl cysteine at alkaline conditions in the presence of sodium salicylate as extractant in a homogeneous solution. The liquid-solid transition of salicylic acid was achieved by adding an aliquot of concentrated phosphoric acid that enables efficient dispersion and phase separation in a single step. Due to the moderate melting point of salicylic acid, its solidification is carried out at room temperature without the need for sample cooling. Critical parameters affecting the efficiency of the derivatization reaction and the microextraction performance were investigated and optimized. The fluorescent analyte derivatives were monitored at λ_ex/λ_em = 340/450 nm. The proposed method was validated in terms of specificity, linearity, precision and trueness. The method was linear in the range of 50–2000 ng mL⁻¹ while the intraday and between days precision was less than 13.7% in all cases. The trueness of the method ranged between 87.9 and 113%. The green character and the applicability of the method were assessed using ComplexMoGAPI and BAGI tools. The developed analytical scheme presented satisfactory performance, and it could be applied in the analysis of selected drugs in human urine samples.