Response surface methodology optimized dispersive liquid–liquid microextraction coupled with surface plasmon resonance of silver nanoparticles as colorimetric probe for determination of captopril

Abstract

A response surface methodology (RSM) based on central composite design was developed to optimize a novel method for the determination of trace levels of captopril by combination of dispersive liquid–liquid microextraction (DLLME) and surface plasmon resonance of silver nanoparticles (AgNPs). In this study AgNPs as a colorimetric sensor were synthesized in situ and used in a versatile DLLME method using carbon tetrachloride as extraction solvent and ethanol as disperser. The presence of captopril affected the production of AgNPs in the organic phase, thereby resulting in an increase of plasmon absorbance intensity of nanoparticles. The effect of different variables such as CTAB, sodium hydroxide and ascorbic acid concentration and also volume of extraction and disperser solvent was investigated and optimized by RSM at two steps. The calibration curve was linear in the range of 0.77–22.50nmolL−1 of captopril, limit of detection was 0.51nmolL−1 and the relative standard deviation for 11.54 and 19.23nmolL−1 of captopril was 2.12 and 0.72%, respectively. The developed method was applied to the determination of the analyte in pharmaceutical, human serum and urine samples with good accuracy and excellent precision.