Use Of Liquid Extraction Research Articles

The Use of Liquid Extraction for the Purification of Solutions from the Nickel Production of JSC Kola MMC from Impurities

The Use of Liquid Extraction for the Purification of Solutions from the Nickel Production of JSC Kola MMC from Impurities

A Subcritical Water Extractor Prototype for Potential Astrobiology Spaceflight Missions

AbstractA top‐level NASA exploration goal is the search for signs of life beyond Earth. Molecular biosignatures can be sought via in situ organic chemical analyses of samples collected from planetary bodies. Current spaceflight‐ready technologies lack the required sensitivity to perform these analyses on key polar organic species primarily due to the low efficiency of transferring these molecules from natural samples into chemical instrumentation. One promising approach to improve the liberation of these molecules from sample matrices prior to analysis is through the use of liquid extraction, in which organic molecules are dissolved in heated, pressurized water. This process has never been performed on a spaceflight mission. As part of instrument maturation efforts, we describe the development of the first spaceflight prototype of a fully automated subcritical water extractor designed to provide this essential functionality on a potential future planetary mission. The prototype extractor was mounted on a Mars test rover platform and successfully operated remotely in the Atacama Desert, Chile. Samples acquired by the rover's drill and sample acquisition/delivery system were remotely transferred to the extractor inlet funnel, and all subsequent extractor operations were performed automatically. To validate the instrument and demonstrate its suitability as a front‐end unit for an organic analyzer, we tested low‐bioload Atacama Desert soil extracts for amino acid content using capillary electrophoresis coupled to laser‐induced fluorescence. We show that hot extraction under subcritical conditions is required to liberate amino acids from the sample, as no amino acids were found in the extract produced at room temperature.

Perspectives on the Use of Liquid Extraction for Radioisotope Purification.

The reliable and efficient production of radioisotopes for diagnosis and therapy is becoming an increasingly important capability, due to their demonstrated utility in Nuclear Medicine applications. Starting from the first processes involving the separation of 99mTc from irradiated materials, several methods and concepts have been developed to selectively extract the radioisotopes of interest. Even though the initial methods were based on liquid-liquid extraction (LLE) approaches, the perceived difficulty in automating such processes has slowly moved the focus towards resin separation methods, whose basic chemical principles are often similar to the LLE ones in terms of chelators and phases. However, the emerging field of flow chemistry allows LLE to be easily automated and operated in a continuous manner, resulting in an even improved efficiency and reliability. In this contribution, we will outline the fundamentals of LLE processes and their translation into flow-based apparatuses; in addition, we will provide examples of radioisotope separations that have been achieved using LLE methods. This article is intended to offer insights about the future potential of LLE to purify medically relevant radioisotopes.

Determination of lipoic acid in human plasma by high-performance liquid chromatography with ultraviolet detection

This paper describes the development and validation of an HPLC method for the determination of protein bound and total lipoic acid in human plasma. The essential steps in the total lipoic acid assay include reduction of disulfide bridge with tris(2-carboxyethyl)phosphine, derivatization via thiol group with 1-benzyl-2-chloropyridinium bromide and HPLC analysis of S-pyridinium derivative. Protein-bound lipoic acid is first separated from free lipoic acid with the use of liquid extraction, converted to its reduced counterpart then processed as total lipoic acid. The method is reproducible, precise and accurate. The inter- and intraday related standard deviation varied from 1.5% to 11.5% and from 1.8% to 19.6%, respectively, while recovery is in the range of 80.0–106.0% and 80.4–110.8%, respectively. The mean concentration of total lipoic acid in healthy donors after supplementation with 600mg and 1200mg was 0.67±0.40μmolL−1 (137.6±82.1μgL−1) and 1.57±0.34μmolL−1 (323.34±70.07μgL−1), respectively.

Identification and quantification of polycarboxylates in detergent products using off-line size exclusion chromatography–nuclear magnetic resonance

The performance of many contemporary detergent products critically depends on polymers. Water-soluble polycarboxylates represent an important class of detergent polymers, and their quantitative assessment in detergent matrices stands as a considerable challenge. The presence of high levels of surfactants is a major complication, due to the strong tendency of surfactants to form micelles and to interact with the polymers. First, we addressed critical steps in the subsequent combined use of liquid extraction and off-line size exclusion chromatography–nuclear magnetic resonance (SEC–NMR) for identification and quantification of polycarboxylates in detergent products. Next, the different steps in the off-line SEC–NMR procedure were optimized with respect to precision and accuracy. This resulted in recoveries of more than 80% for maleic acid/acrylic acid copolymers; in detergent products a proportional bias of 30% is achieved. The method showed good precision with a relative standard deviation of within-laboratory reproducibility between 5% and 14%.

Use of monoisooctylmethylphosphonic acid and its trivalent iron salt in determining radionuclides in effluents

It is possible to determine the biologically most hazardous radionuclides 9~ ~37Cs, 239'238Pu, 24~Am, and so on in effluents at the level of 0.i MPC if large concentration factors can be provided during the extraction. Methods exist for determining small amounts of 9~ (from 9Oy), plutonium, and other radionuclides in aqueous solution by the use of liquid extraction with tri-n-butyl phosphate (TBP) [1-3], di(2-ethylhexyl)phosphoric acid (D2EHPA) [4-6], trialkylphosphine oxides [7], and other reagents.