Comparative Extraction of Aluminum Group Metals Using Acetic Acid Derivatives with Three Different-Sized Frameworks for Coordination

We prepared acetic acid derivatives using three different frameworks, calix[4]arene, alkenyltrimethylol, and trihydroxytriphenylmethane, which differ in the number and size of their coordination sites. We further investigated the extraction properties for aluminum group metal ions. All three extraction reagents exhibited increased extraction compared with the corresponding monomeric compounds, owing to structural effects. The extraction reaction and extraction equilibrium constants were determined using a slope analysis. Their extraction abilities, separation efficiencies, and potential coordination modes are discussed using the extraction equilibrium constants, half-pH values, and spectroscopic data. The calix[4]arene and trihydroxytriphenylmethane derivatives demonstrated allosteric co-extraction of indium ions (In3+) with an unexpected stoichiometry of 1:2.

Synthesis and study of the extraction properties ofnew phosphorus-containing extractants of heavy metals

The metallurgical industry is one of the cornerstones of contemporary chemical science and industry and it is developing rapidly in many countries. The widespread introduction of metal extraction, concentration and separation as the most productive methods entails the need to search for and create new effective metal extractants. Among the compounds, suitable for use as extractants, the most widespread are organic phosphites and phosphates, which allow performing extraction processes with good selectivity and efficiency. The purposes of this article include finalizing the optimal synthesis conditions and developing larger batches of 4,5-dimethyl-2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphospholane and 5,5-dimethyl-2-(2,2,3,3,4,4,5,5- octafluoropentoxy)-1,3,2-dioxaphosphorinane, and study of the extraction properties of the obtained phosphorus- containing heterocyclic compounds in the separation of uranium from the commercial desorbate. The synthesis of new representatives of the indicated polyfluoroalkylated five- and six-membered heterocyclic phosphorus compounds was conducted using the interaction of 2-chloro-1,3,2-dioxaphospholane with trifluoroethanol and the substitution–cyclization reaction of polyfluoroalkylated dichlorophosphite with 2,2-dimethyl- 1,3-propanediol. Reactions easily proceed in triethylamine–hexane or pyridine–diethyl ether systems at temperatures ranging between minus ten to room temperature, with the output of target heterocycles of 53–57%. The studies of extraction properties of synthesized poly-fluorinealkylated dioxaphospholane and dioxaphosphorinane show that the use of these phosphorus-containing heterocyclic compounds as extractants allows extracting a technically valuable metal up to 12.4 and 15.2%, respectively. Nitric and sulfuric acid solutions of commercial desorbate of hydrometallurgical production in Kazakhstan were used as feedstock in the extraction process.

Mass Spectrometric Quantification of the Antimicrobial Peptide Pep19-2.5 with Stable Isotope Labeling and Acidic Hydrolysis

Sepsis is the number one cause of death in intensive care units. This life-threatening condition is caused by bacterial infections and triggered by endotoxins of Gram-negative bacteria that leads to an overreaction of the immune system. The synthetic anti-lipopolysaccharide peptide Pep19-2.5 is a promising candidate for the treatment of sepsis as it binds sepsis-inducing lipopolysaccharides and thus prevents initiation of septic shock. For clinical evaluation precise quantification of the peptide in blood and tissue is required. As the peptide is not extractable from biological samples by commonly used methods there is a need for a new analysis method that does not rely on extraction of the peptide. In order to quantify the peptide by mass spectrometry, the peptide was synthesized containing 13C9,15N1-labeled phenylalanine residues. This modification offers high stability during acidic hydrolysis. Following acidic hydrolysis of the samples, the concentration of 13C9,15N1-labeled phenylalanine determined by LC-MS could be unambiguously correlated to the content of Pep19-2.5. Further experiments validated the accuracy of the data. Moreover, the quantification of Pep19-2.5 in different tissues (as studied in Wistar rats) was shown to provide comparable results to the results obtained with radioactively-labeled (14C) Pep19-2.5- Radioactive labeling is considered as the gold standard for quantification of compounds that refrain from reliable extraction methods. This novel method represents a valuable procedure for the determination of Pep19-2.5 and sticky peptides with unpredictable extraction properties in general.