Enhanced microextraction kinetics: Sorptive-dispersive vs. conventional techniques on rotating disks

A new approach based on Stir Bar Sorptive Dispersive Microextraction (SBSDME), termed Rotating Disk Sorptive Dispersive Extraction (RDSDE), was developed to confirm and quantify the kinetic advantages of sorbent-based dispersive techniques compared to their non-dispersive counterparts. Among non-dispersive techniques, Rotating Disk Sorptive Extraction (RDSE) allows for a direct comparison with its dispersive counterpart, as the sorbent phase in RDSE can be confined within the disk cavity using the exact same amount as in the dispersive mode. This comparison is not feasible in stir bar sorptive extraction.

The advantages of RDSE combined with the dispersion of magnetic sorbent materials were explored using RDSDE technology. Magnetic activated carbon (MAC) derived from avocado seeds was used as the sorbent, with triclosan (TCS), bisphenol A (BPA), ibuprofen (IBU), and 1-hydroxy-ibuprofen (1-OH-IBU) as representative analytes. The RDSDE method was optimized for efficiency and speed. Optimal conditions were: 10 mg of MAC, 20 min extraction at pH 2, acetone as desorption solvent and 10 min desorption. These parameters provided the best analytical response with minimal time and resource use. The method was then validated, and a kinetic comparison was performed. The results demonstrated that RDSDE reaches extraction equilibrium in approximately 20 min, significantly faster than RDSE. The initial extraction velocities were between 12 times higher for BPA and 43 times higher for IBU in the dispersive mode.

The kinetic comparison clearly shows that RDSDE is a more efficient extraction technique due to its rapid extraction equilibrium. The dispersive mechanism plays a crucial role in accelerating analyte extraction, as evidenced by the steeper extraction profiles of RDSDE compared to RDSE. Importantly, this study presents the first direct kinetic comparison between RDSDE and conventional RDSE, highlighting the novelty of the approach. This underscores the potential of RDSDE as a faster and more efficient method for extracting target compounds from aqueous samples, offering significant advantages in analytical performance and operational efficiency.