Aluminum based metal-organic framework-polymer monolith in solid-phase microextraction of penicillins in river water and milk samples

• Different aluminum based MOF-polymer monoliths in SPME of hydrophilic compounds.
• MIL-53-polymer was applied in SPME of penicillins in river water and milk.
• The obtained recoveries for penicillins were >81% in river water and milk samples.
• LODs and LOQs of MIL-53-polymer were <0.26 μg L−1 and <0.87 μg L−1.

In this study, aluminum based metal-organic framework (Al-MOF)-organic polymer monoliths were prepared via microwave-assisted polymerization of ethylene dimethacrylate (EDMA), butyl methacrylate (BMA) with different weight percentages of Al-MOF (MIL-53; 37.5–62.5%) and subsequently utilized as sorbent in solid-phase microextraction (SPME) of penicillins (penicillin G, penicillin V, oxacillin, cloxacillin, dicloxacillin, nafcillin). The Al-MOF-polymer was characterized using Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and SEM-energy-dispersive X-ray spectroscopy (SEM-EDS) to clarify the retained crystalline structure well as the homogeneous dispersion of Al-MOF (MIL-53) in polymer monolith. The developed Al-MOF-polymer (MIL-53) monolithic column was evaluated according to its extraction recovery of penicillins. Several parameters affecting the extraction recoveries of penicillins using fabricated Al-MOF-polymer (MIL-53) monolithic column including different MIL-53 weight percentages, column length, pH, desorption solvent, and mobile phase flow rate were investigated. For comparison, different Al-based MOFs (MIL-68, CYCU-4 and DUT-5) were fabricated using the optimized condition for MIL-53-polymer (sample matrix at pH 3, 200 μL desorption volume using methanol, 37.5% of MOF, 4-cm column length at 0.100 mL min−1 flow rate). Among all the Al-MOF-polymers, MIL-53(Al)-polymer still afforded the best extraction recovery for penicillins ranging from 90.5 to 95.7% for intra-day with less than 3.5% relative standard deviations (RSDs) and inter-day precision were in the range of 90.7–97.6% with less than 4.2% RSDs. Meanwhile, the recoveries for column-to-column were in the range of 89.5–93.5% (<3.4% RSDs) while 88.5–90.5% (<5.8% RSDs) for batch-to-batch (n = 3). Under the optimal conditions, the limit of detections were in the range of 0.06–0.26 μg L−1 and limit of quantifications between 0.20 and 0.87 μg L−1. Finally, the MIL-53-polymer was applied for the extraction of penicillin in river water and milk by spiking trace-level penicillin for as low as 50 μg L−1 and 100 μg L−1 with recoveries ranging from 80.8% to 90.9% (<6.7% RSDs) in river water and 81.1% to 100.7% (<7.1% RSDs) in milk sample, respectively.