Molecularly imprinted polymer-based dispersive solid-phase extraction for the selective determination of carisoprodol in biological and pharmaceutical samples

Abstract

Carisoprodol (CSP) is one of the most common antispasmodic drugs used to reduce muscle spasms; however, it is also abused due to its mind-altering effects. Consequently, its abuse leads to the major concern of increased risk of fatal road accidents due to impaired driving. Therefore, it is crucial but challenging for forensic toxicologists to effectively extract and detect CSP in complex biological matrices. Hence, herein, a novel analytical technique based on a molecularly imprinted polymer (MIP) coupled with dispersive solid-phase extraction (MIP-DSPE) was developed for the simple, rapid, selective extraction and analysis of CSP by applying gas chromatography-mass spectrometry (GC-MS) from pharmaceutical and biological samples such as urine and blood. MIP was successfully synthesized via bulk polymerisation utilizing CSP as the template, methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as a crosslinker, and azobisisobutyronitrile (AIBN) and acetonitrile as an initiator and porogen, respectively. Further, the as-synthesized polymer was characterized via field emission-scanning electron microscopy (FE-SEM) and Fourier-transform infrared spectroscopy (FTIR). An equilibrium adsorption experiment was performed to determine the binding affinity of the synthesized polymer. The different parameters affecting the efficiency of MIP-DSPE were optimized for the selective estimation of CSP in urine, blood, and pharmaceutical samples. The developed method exhibited reasonable linearity for the calibration range of 0.1–10 μg mL⁻¹ together with correlation coefficients (R²) of more than 0.9993, 0.9993, and 0.9996 for urine, blood, and pharmaceutical samples, respectively. Under the optimized conditions, the percentage recoveries of CSP from urine, blood, and pharmaceutical samples were in the range of 83.9–113.2%. The limit of detection (LOD) and limit of quantification (LOQ) for urine, blood, and pharmaceutical samples were estimated to be 0.0052, 0.0076, and 0.0050 μg mL⁻¹ and 0.0171, 0.0250, and 0.0165 μg mL⁻¹, respectively. Moreover, the intra-day and inter-day precisions (n = 5) were under 7% and 11%, respectively. In addition, the greenness of the proposed technique was assessed employing the ComplexGAPI tool.