Magnetic multi-walled carbon nanotubes as a valuable option for the preconcentration of non-steroidal anti-inflammatory drugs in water

Magnetic Solid-Phase Extraction Based on Magnetite-Multiwalled Carbon Nanotubes of Non-Steroidal Anti-Inflammatories from Water Followed by LC-ESI-MS/MS

An analytical method based on liquid chromatography-electrospray ionization-tandem mass spectrometry detection (LC-ESI-MS/MS) has been developed for the determination of pharmaceutical compounds in water samples. Five non-steroidal anti-inflammatory drugs (NSAIDs) namely Naproxen, Ketoprofen, Piroxicam, Diflunisal and Celecoxib were investigated. Magnetic solid phase extraction (MSPE) was used for sample pre concentration of water samples and magnetic carbon nanotubes (Fe3O4-MWCNTs) were considered as solid phase extraction sorbent. Important parameters influencing the extraction efficiency such as nature and volume of eluent, sample pH and adsorbent mass were optimized. The developed MSPE method involved 75 mg of Fe3O4-MWCNTs sorbent, 5 mL of water sample at pH = 4 and 5 mL of 10% ammonia in methanol in the elution step. Under the optimized extraction conditions, linearity, detection and quantification limits and reproducibility were evaluated. The proposed method was successfully applied to the analysis of NSAIDs in surface waters, and mean recoveries of all the NSAIDs were above 90% with relative standard deviations < 17%. The detection and quantification limits were comprised between 0.05-3.6 ng.mL-1 and 0.2-11.9 ng.mL-1, respectively.

Synthesis and characterization of a novel magnetic porous carbon coated with poly(p-phenylenediamine) and its application for furfural preconcentration and determination in baby food and dry milk powder samples

The aim of the current research is to develop a MSPE method for the determination of furfural in baby food and dry milk samples. In this regard, a novel magnetic porous carbon composite coated with poly(p-phenylenediamine) was fabricated, characterized, and then applied to the preconcentration/extraction of furfurals from baby food and dry milk powder samples. Initially, magnetic nanoparticles (Fe3O4) were synthesized, and then coated with a metal-organic framework layer named MIL-101(Fe). Afterward, the magnetic MIL-101(Fe) was subjected to calcination under a nitrogen atmosphere and magnetic porous carbon was achieved. Finally, a layer of poly(p-phenylenediamine) was coated on the magnetic porous carbon. The structure of the nanocomposite was investigated with various methods, including FT-IR spectroscopy, electron microcopies (SEM and TEM), VSM, and XRD. The fabricated nanocomposite was applied in magnetic solid-phase extraction of furfural and hydroxymethyl furfural and their determination with liquid chromatography. The effect of experimental variables was explored by using an experimental design approach. The LODs and linear range for the target furfurals were 1.0-2.0 μg kg-1 and 3.0-500 μg kg-1, respectively. The method's repeatability was explored using RSD values and was found to be in the range of 5.2-6.4% (one-day, n = 5) and 9.1-10.8% (day to day, n = 3). Eventually, this new method was employed for the extraction/quantification of target compounds in baby food and dry milk powder samples.