Synthesis of quaternized PAMAM-grafted magnetic carbon nanotubes as anion exchange adsorbent for highly efficient and rapid extraction of non-steroidal anti-inflammatory drugs from environmental waters.

Extensive prescription and consumption of non-steroidal anti-inflammatory drugs (NSAIDs) in humans and livestock medicines lead to their constant discharge into the natural waters posing deleterious ecological and health concerns. Considering their existence in water as anions, a new adsorbent containing a large proportion of quaternary ammonium groups for anion-exchange micro-magnetic solid phase extraction (AE-µ-MSPE) was designed and synthesized by grafting G2.0 of the poly(amidoamine) dendrimers (G2.0PAMAM) onto the magnetic carbon nanotubes (MCNTs) followed by quaternization with glycidol. After successful characterization by NMR, FT-IR, XPS, SEM, TEM, EDX, XRD, VSM, and TGA, the synthesized adsorbent QPAMAM@MCNTs in combination with HPLC-UV was applied for the preconcentration and determination of four NSAIDs in environmental waters. Extraction parameters were optimized using Box-Behnken design (BBD), while desorption conditions were refined via a univariate approach. This anion-exchange adsorbent exhibited high extraction recoveries (86.2-96.5 %) through synergistic hydrogen bonding, π-π stacking, hydrophobic, and anion-exchange/electrostatic interactions. The developed method demonstrated excellent analytical performance, with limits of detection ranging from 0.06 to 0.13 µgL⁻¹, linearity between 0.5-50 µgL⁻¹ (R² = 0.9992-0.9997), enrichment factors of 172-195, and intra-/inter-day RSDs below 7.7 %. Overall, the proposed method offers a rapid, simple, and sensitive approach that can be opted for the selective enrichment and determination of acidic/anionic contaminants including pharmaceuticals and pesticides in environmental waters and potentially other complex matrices such as drug formulations, food, and biological samples.