Terephthalaldehyde–Phenolic Resins as a Solid-Phase Extraction System for the Recovery of Rare-Earth Elements

Rare-earth elements (REEs) are involved in most high technology devices and have become critical for many countries. The progress of processes for the extraction and recovery of REEs is therefore essential. Liquid–solid extraction methods are an attractive alternative to the conventional solvent extraction process used for the separation and/or purification of REEs. For this purpose, a solid-phase extraction system was investigated for the extraction and valorization of REEs. Ion-exchange resins were synthesized involving the condensation of terephthalaldehyde with resorcinol under alkaline conditions. The terephthalaldehyde, which is a non-hazardous aromatic dialdehyde, was used as an alternative to formaldehyde that is toxic and traditionally involved to prepare phenolic ion-exchange resins. The resulting formaldehyde-free resole-type phenolic resins were characterized and their ion-exchange capacity was investigated in regard to the extraction of rare-earth elements. We herein present a promising formaldehyde and phenol-free as a potential candidate for solid–liquid extraction REE with a capacity higher than 50 mg/g and the possibility to back-extract the REEs by a striping step using a 2 M HNO3 solution.

Effect of Microwave-Assisted Aqueous Two-Phase Extraction of α-Solanine from S. retroflexum and Analysis on UHPLC-qTOF-MS

A new, fast and efficient method, hyphenated microwave-assisted aqueous two-phase extraction (MA-ATPE) was applied in the extraction of α-solanine from Solanum retroflexum. This environmentally friendly extraction method applied water and ethanol as extraction solvents. Central composite design (CCD) was performed which included numerical parameters such as time, mass of plant powder and microwave power. The categorical factors included the chaotrope — NaCl or the kosmotrope — Na2CO3. Fitting the central composite design response surface model to the data generated a quadratic model with a good fit (R2 = 0.920). The statistically significant (p < 0.05) parameters such as time and mass of plant powder were influential in the extraction of α-solanine. Quantification of α-solanine was achieved using a robust and sensitive feature of the ultra-high performance quadrupole time of flight mass spectrometer (UHPLC-qTOF-MS), multiple reaction monitoring (MRM). The optimized condition for the extraction of α-solanine in the presence of NaCl and Na2CO3 was a period of 1 min at a mass of 1.2 g using a microwave power of 40%. Maximal extraction of α-solanine was 93.50 mg kg−1 and 72.16 mg kg−1 for Na2CO3 and NaCl, respectively. The synergistic effect of salting-out and microwave extraction was influential in extraction of α-solanine. Furthermore, the higher negative charge density of the kosmotrope (Na2CO3) was responsible for its greater extraction of α-solanine than chaotrope (NaCl). The shorter optimal extraction times of MA-ATPE make it a potential technique that could meet market demand as it is a quick, green and efficient method for removal of toxic metabolites in nutraceuticals.

A bioanalytical screening method for Enterococcus faecalis RNPP-type quorum sensing peptides in murine feces

Background: Bacteria coordinate their behavior as a group via communication with their peers, known as ‘ quorum sensing’. Enterococcus faecalis employs quorum sensing via RNPP-peptides which were not yet reported to be present in mammalian biofluids. Results: Solid phase extraction of murine feces was performed, followed by ultra high performance liquid chromatography (UHPLC–MS/MS) in multiple reaction monitoring (MRM) mode (in total <90 min/sample) for the nine known RNPP peptides. Limits of detection ranged between 0.045 and 52 nM. Adequate identification criteria allowed detection of RNPP quorum sensing peptides in 2/20 wild-type murine feces samples (i.e., cAM373 and cOB1). Conclusion: A fit-for-purpose UHPLC–MS/MS method detected these RNPP peptides in wild-type murine feces samples.