Preparation of Gemini-Functionalized Cellulose Paper Sorptive Phases for Enrichment of Non-Steroidal...

Cationic cellulose paper is a promising adsorbent for acidic compounds in water. However, cellulose modified with glycidyl trimethyl ammonium chloride (EPTAC) often exhibits compromised structural integrity and readily disperses in water. In this study, a Gemini quaternary ammonium salt (Gemini-QAS) was synthesized via nucleophilic substitution of N,N,N',N'-tetramethyl-1,6-hexanediamine with epichlorohydrin and subsequently used for the etherification of cellulose paper. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and zeta potential analyses confirmed the successful incorporation of the Gemini-QAS onto the cellulose substrate. Tensile testing demonstrated that the Gemini-modified cellulose paper (GCP) exhibited enhanced mechanical strength in both dry (25.16 MPa) and wet (1.54 KN/m) states, and the wet tensile strength ratio was 0.29, whereas EPTAC-modified cellulose paper showed decreased wet tensile strength (0.51 KN/m) and ratio (0.16). Batch experiments demonstrated that the optimal adsorption and desorption conditions for GCP on 12 weakly acidic non-steroidal anti-inflammatory drugs (NSAIDs) were pH 7.0, an adsorption time of 30 min, and an eluent of 2% formic acid-methanol. Then, these 12 NSAIDs were extracted by GCP from real water samples and quantified by high-performance liquid chromatography-tandem mass spectrometry. The analytical method achieved limits of detection ranging from 0.02 to 0.64 µg/L and limits of quantification between 0.07 and 2.11 µg/L. Precision, expressed as intra-day relative standard deviation (RSD), remained below 10%, and inter-day RSD below 12%. The relative recoveries ranged from 71% to 102% at spiking levels of 10 and 50 µg/L, while recoveries at 1 µg/L ranged from 65.1% to 89.7% due to more pronounced matrix effects. This work successfully resolves the poor aqueous stability and fiber dispersion issues of EPTAC-modified cellulose, providing a green, low-cost, and robust paper-based sorptive phase for trace NSAID monitoring in environmental water, which aligns with the principles of sustainable analytical chemistry.