Leveraging micro-disk array device for sensitive duloxetine detection in human urine

An innovative microdisk array (MDA)-based microextraction technique was developed for the quantification of duloxetine in human urine, followed by HPLC-FLD determination. The MDA system introduces a reusable and miniaturized extraction format, where an array-type configuration enhances mass transfer efficiency while reducing both sample manipulation and solvent requirements. The device was constructed by concentrically positioning two C18 microdisks onto a stainless-steel spinal needle, secured with frit-based supports. The extraction procedure involved immersing the MDA in the aqueous sample for 40 min, followed by a short rinsing step with water and subsequent elution of the analyte using 750 μL of methanol. Experimental variables influencing both adsorption and desorption processes were thoroughly optimized. Under the selected conditions, the method exhibited a linear response within the concentration range of 25-500 ng/mL and a limit of detection of 15 ng/mL. Precision, evaluated as intra- and inter-day variability, remained below 3.1%, while accuracy, expressed as relative recovery, ranged between 102.4% and 118.1%. The greenness of the analytical procedure was evaluated using the MA index, confirming its low environmental impact. Finally, the applicability of the method was verified through successful analysis of human urine samples, demonstrating the potential of the MDA-based approach as an efficient and sustainable sample preparation strategy.