New Method For Separation Research Articles

New methods of transplutonium element separation and determination

Some recently developed new methods of separation and determination of transplutonium elements (TPEs) are described. The solvent extraction of TPE III by bidentate organophosphorus reagents from strongly acidic, salt-containing media and their extraction from alkaline solution by various reagents as well as isolation of TPEs in “unusual” oxidation states are discussed. Stabilization of americium as Am IV, Am V, Am VI and berkelium as Bk IV is considered. The separation of actinides and rare earth elements can be carried out by countercurrent chromatography which is based on the retention of the organic phase in a rotating column of a planetary centrifuge under the action of centrifugal forces while the stationary phase is continuously pumped through. It has been shown that TPEs can be successfully separated by this technique. Attention has been paid mainly to consideration of contemporary methods for determination of actinides, special distinction of such methods being low limits of determination, high precision and selectivity. A large number of coulometric methods for determination of americium and berkelium characterized by high precision and selectivity as well as luminescence methods have been developed.

Determination of phosphorus in metals by neutron activation and chemical separation as hydride

Phosphorus at trace levels alters the properties of metals and alloys. Its determination was investigated by radiochemical neutron activation analysis. Separation by solvent extraction or by evolution as P0 showed to be neither selective nor quantitative in presence of a metallic matrix. Therefore, a new method of separation by reduction to phosphorus hydride followed by liquid scintillation counting was investigated. This method is quantitative in the case of non-radioactive iron doped with radioactive phosphorus. At present, the separation is not quantitative for irradiated iron samples, owing probably to hot atom or radiation effects. A detection limit of 0.002 μg is expected.

A new method of separation of multi-atomic ions by mobility at atmospheric pressure using a high-frequency amplitude-asymmetric strong electric field

The general principles of a new method of ion separation in dense air—gas media using an asymmetric high-frequency electric field are given. With this method ion separation is realized due to the different dependences of the individual transverse ion mobility coefficients on the electric field. The drift-spectra of the ions from a homological series of tertiary amines are presented as well as the results of mass spectrometric identification of the various ions representing the separate peaks in the mobility spectra. The possibility of continuous recording and identification of trace amounts of amines in atmospheric air is shown.

Resolution of three forms of superoxide dismutase by immobilised metal affinity chromatography

A new method for separation of three forms of superoxide dismutase (SOD) using immobilised metal affinity chromatography (IMAC) is reported. Fe-, Mn- and Cu/Zn-SODs were eluted sequentially from Cu 2+-IMAC column with an increasing gradient of a counter ion (NH + 4) run in combination with an increasing pH gradient (6.8–7.8). The combined gradient elution method resulted in separation of SODs with high resolution, the three proteins being eluted in electrophoretically homogeneous forms. Similar preparation could not be achieved by either increasing gradient of a counter ion or decreasing pH gradients used separately. The described methodology has been successfully applied for separation of three SODs from a protozoan parasite, indicating that this combined gradient elution system for IMAC offers new possibilities for the high-resolution separation of proteins exhibiting only minor differences in their amino acid composition and structure.

Investigation of a new method for separation of neutrophils from a small volume of human blood

We have already reported a neutrophil separation method for the multiple simultaneous measurement of neutrophil chemiluminescence. However, when the reported separation method was used, at least 4 ml of venous blood was needed to collect enough neutrophils for chemiluminescent measurement. Because of this blood volume, there is a limitation on applications of the multiple simultaneous method for neonates, infants, and in some clinical situations. To expand the application of this neutrophil chemiluminescence measurement into clinical and health science areas, we have developed a new method for separation of neutrophils from a relatively small amount of blood (500 microliters). In addition, the influences of remaining red blood cells and hemoglobin levels in the neutrophil fraction on the chemiluminescence were examined to determine the necessity for elimination procedures. The new separation method used a capillary tube (length, 130 mm; outside diameter, 5 mm; thickness, 0.8 mm) with density gradient reagents (Histopaque 1077 and 1119). After centrifugal separation (500 g, 30 min), the neutrophil fraction was isolated with 93.1 +/- 4.7% purity and 60.6 +/- 11.1% yield. This purity and yield were comparable to or better than those with the previously reported method, while levels of remaining red blood cells and hemoglobin were about the same. Remaining red blood cells and hemoglobin in the neutrophil fraction acted on the chemiluminescence as a quencher. For the correct estimation of neutrophil chemiluminescence, elimination of remaining red blood cells and hemoglobin in the neutrophil fraction is necessary. This new neutrophil separation method is a very useful method, especially for cases in which available blood amounts are limited.

Studies on organo-mercury compounds speciation

Four studies on organo-mercury compounds speciation carried out in the analytical chemistry laboratory of the University of Santiago are briefly described and discussed. Search for new methods of separation based on liquid chromatography as well as quality control and application studies have been started and the results obtained up to the end of 1990 are presented.

Molecular separation by thermosensitive hydrogel membranes

A new method for separation of molecules of different size is presented. The method is a useful addition to conventional separation methods which depend mainly on gel permeation chromatography using size exclusion. In the new method, hydrogel membranes are used which swelling level can be thermally controlled. In this study, a crosslinked poly(N-isopropylacrylamide—co-butylmethacrylate 95:5mol%) membrane is used and three solutes of distinct molecular size: two dextrans with molecular weights of 150,000 and 4,400 g/mol respectively and uranine with a molecular weight of 376 g/mol. The swelling of the membranes as function of temperature was measured as well as the influence of the swelling level on the permeability of the three solutes. the influence of the swelling level and the solute size on the permeability was as expected from the free-volume theory. Based on these permeability phenomena, separation was performed in a continuous way by varying the membrane swelling at the appropriate time. A linear relationship between inverse membrane hydration and solute diffusion was found for uranine and dextran ( MW=4,400), indicating the validity of the free-volume theory.

A new method of separation and quantitation of mucus glycoprotein in rat gastric mucus gel layer and its application to mucus secretion induced by 16,16-dimethyl PGE2

A method was established for recovering the mucus gel layer of rat gastric mucosa without damage to underlying surface epithelium. The mucus gel was solubilized by stirring the gastric mucosa in a solution of N-acetylcysteine (NAC), a mucolytic agent. Optimal mucus gel solubilization was possible by treatment with 2% NAC for 5 minutes at room temperature. Mucus glycoprotein was quantitatively extracted and measured from the mucus gel sample obtained by the NAC treatment. This treatment caused no damage to surface epithelial cells, as observed by a light microscope. Besides NAC, pronase solution was also adequate for solubilizing the mucus gel layer without any damage to the surface epithelium. However, extraction and measurement of mucus glycoprotein from the pronase-treated mucus gel sample was not possible due to contamination by high molecular hexose-containing substances which were eluted along with the mucus glycoprotein from the column of Bio-Gel A-1.5m. This NAC method was used to examine changes in mucus glycoprotein content in the mucus gel at one hour following the oral administration of 16,16-dimethyl prostaglandin E2. A significant increase in mucus glycoprotein of the gel was brought about by the prostaglandin treatment. Thus, the present method was suitable for estimating the amount of mucus secreted in to the mucus gel layer.

New methods for separation and recovery of biomolecules

New methods and applications in the separation of biomolecules are reviewed, with an emphasis on the large-scale recovery of proteins. Highlights include the advent of flow-through particles in perfusion chromatography, which allows for very high flow rates, while retaining a high chromatographic efficiency.

Latest achievements in the analytical chemistry of actinides

New methods for separation and determination of actinides, widely used in analysis of actinides in technological and environmental samples are reviewed. Special attention is paid to obtaining and stabilizing transplutonium elements. (TPE) in extreme oxidation states. Their use in analytical practice resulted in expanding possibilities of methods for separation and determination of TPE. Solvent extraction, sorption and extraction chromatography are the basic methods for separation of TPE. Solvent extraction, sorption and extraction chromatography are the basic methods for separation of TPE. Methods of separation in gas phase and some other methods such as precipitation and coprecipitation are applied, however, to a lesser degree. Trends of development of these methods including those of various types of membrane extraction that succeeded in separation of TPE in both trivalent and other valence states have been shown. Attention is paid mainly to consideration of modern methods for determination of actinides, special distinction of such methods being low limits of determination, high precision and selectivity. Alpha- and beta-spectrometric methods with semiconductor detectors are the most advanced among various methods based on registration of nuclear radiation. Tremendous success has been achieved in development of emission-spectrometric methods for determination of trace amounts of actinides and various impure elements occurring in samples of actinides. Sensitive mass-spectrometric methods are widely used for determination of both isotope composition and content of elements in various samples including those which are highly radioactive. More simple and precise titrimetric methods based on using oxidizing-reducing or complexing agents are developed successfully. A large number of coulometric methods for determination of americium and berkelium, characterizing high precision and selectivity as well as luminescence methods have been developed.

New Method for Separation and Purification of Polyunsaturated Fatty Acids Using a Silver Ion-exchanged Spherical Clay Mineral

New method was developed for separation and purification of polyunsaturated fatty acid ethyl esters using a silver ion-exchanged spherical clay mineral [SC (Ag)]. The SC (Ag) was prepared by ion-exchanging silver ion into synthetic hectorite that had been spray-dried to form a spherical shape. Ethyl icosapentaenoate and ethyl docosahexaenoate were separated and purified from the mixture of fatty acid ethyl esters originated from several natural lipids, using SC (Ag) preparative columns under the step gradient condition of organic solvent.

SEPARATION AND CONCENTRATION OF METALS BY SIMULTANEOUS EXTRACTION AND BACK-EXTRACTION METHOD UNDER CONDITIONS OF HIGH SPEED STIRRING

A new method for separation and concentration of metals was investigated by simultaneous extraction and back-extraction using two vessels with a Teflon phase separator. The behavior of extraction and back-extraction regarding the oxinate of manganese was examined mainly under the conditions of high speed stirring. The recovery of Mn extracted into 20 ml of chloroform from 250 ml of an aqueous solution was 100% after 30 min of stirring (3000rpm) using 100 ml of a stripping solution (pH 1.0) for back-extraction. The ratio of aqueous volumes in each vessel was about 8 under the best conditions for the recovery of metal

A 15N tracer method for the measurement of dissolved organic nitrogen release by phytoplankton

We present a new method for separation of dissolved organic nitrogen (DON) from dissolved inorganic nitrogen (DIN) in marlne samples which permlts the measurement of DO'*N production during DII5N uptake and regeneration experiments. Ion retardat~on resin was used to separate DI1'N from DOI'N and the isolated D0I5N was subsequently analyzed by mass spectrometry Variat~on in D0I5N atom % enrichment in duplicate samples, determined w ~ t h the ion retardation column method, was less than 40 . We also separated the low n~olecular weight (LMW) from total D015N using ultrafiltration and found the ratio of these variables to be a useful index in determining what release processes were likely occurring in a given sample. Examples are presented from 2 types of experiments conducted in Chesapeake Bay waters: first, a 6 h time-course of D015N release from both NH,' and I5NO3uptake, and second, a series of short-term (0.5 h) release measurements from 15NH,* uptake over the course of a day. In the former, total DO1% release rates resulting from 15NH,* uptake were several-fold higher than those resulting from IsNO3uptake due to extremely low rates of incorporat~on of NO? into cellular organic material. The release of LMW DOI'N resulting from I5NH,+ uptake decreased from 78 to 21 % of total D0I5N release during the 6 h incubation which suggests that processes other than direct release by phytoplankton (e.g. sloppy feeding, cell lysis) likely became more important as the incubation progressed In the latter expenment, LMW DO'% release was 0 to 16 % of total D0I5N release, which indicates that, in this case, also, processes other than direct release by phytoplankton were dominating the flux of DON from phytoplankton.

A new method for separation of niobium from zirconium with silica gel.

The adsorption behaviors of niobium and zirconium on silica gel and some other adsorbents were investigated in various concentrations of nitric acid or hydrochloric acid. Niobium is strongly adsorbed on silica gel in a concentrated nitric acid solution, while zirconium is not. In a concentrated hydrochloric acid solution, niobium is weakly adsorbed. Based on the results, a new simple separation method of niobium from other radionuclides especially zirconium is developed. In this method, niobium can be recovered by 81%, and separation from zirconium is complete.The method was applied to separation of radioniobium from the neutron-irradiated zirconium wire and from the neutron-irradiated uranium with the results of complete elimination of other radionuclides present.

Application of the ‘Multivir’ method to separation of droplets and solid particles from gases

New types of packing for separation of droplets and solid particles from gases have been proposed. The Multivir packings consist of adjacent layers of strips spaced uniformly. The layers of strips are placed oblique to each other. A gas stream flows through the packing in the form of a large number of smaller streams which cross each other spatially and induce rotational motion in each other. Under the centrifugal force, solid particles and droplets in the gas stream settle on the surfaces of the strips in the packing. A simplified mathematical model describing the phenomenon of particle separation in Multivir packings is presented. Examples of industrial applications of this new method for separation of droplets and solid particles from gases are also given.

ChemInform Abstract: New Method of Separation of Hydroxydiphenylphthalide Isomers from Their Reaction Mixture.

AbstractThe reaction between the acid (I) and phenol (II) yields a mixture of the main product (III) and its isomer (IV).

A recursive method for the separation of upgoing and downgoing waves of vertical seismic profiling data

An important part of the processing of vertical seismic profiling (VSP) data is the separation of upgoing and downgoing waves. I introduce a new method for separation based on a time‐domain recursive linear filter. The separation method uses an approximation to an optimal, frequency‐domain, nonlinear filter solution as the starting point. The time‐domain recursive linear (approximate) filter converges to the optimal (exact) solution. Since the computation is in the time domain and since this filter is linear, some of the temporal aliasing and other problems resulting from the forward and inverse Fourier transforms are avoided. Specifically, instability for some frequencies (spectral singularities) is not experienced here. This method uses a priori information of the opposite stepouts of the upgoing and downgoing waves. Equal spacing between borehole measurement points is not required. Further, the computational time may be controlled according to the desired accuracy. An important feature of this method is that it locates the reflecting boundaries of the subsurface. Having located the homogeneous layers, it allows variable‐length windows of traces for separation, which eliminates the undesirable effects of smearing and extending wave fields beyond their origins. Also, knowledge of acoustic impedances for accurate implementation of the optimum filter is no longer required.

Liquid-phase polymer-based retention, a new method for separation and preconcentration of elements

A method based on the retention of inorganic ions by water-soluble polymeric reagents (liquid-phase polymer-based retention) in a membrane filtration cell is suggested for the separation and preconcentration of various elements. The preseparated elements remain in the aqueous solution, which is convenient for most instrumental methods of completing the analysis. The water-soluble poly(ethyleneimine) and its thiourea and methylated derivatives are shwon to be useful for retention of different inorganic ions and their separation from elements not bound to the polymer reagent.

Aromatic and nitrogen-containing acid separation by reversed-phase high performance liquid chromatography and identification by photodiode array detector.

A new method of separation and identification of aromatic and nitrogen-containing acids is presented. Fifty-seven different acid standards were separated by reversed-phase high performance liquid chromatography (HPLC). Detection and identification of the acids by ultraviolet (UV) spectra using a photodiode array detector (DAD) is demonstrated. Peak height ratios are reported and complete UV spectra of these acids are displayed. Possible applications of this technique are demonstrated using patients' urines.

Dipole correlation functions and intermolecular torques in nematic phase of EBBA and PAA

A new method for separation of the orientational contribution from the vibrational relaxation part in the IR absorption bands of ordered liquid crystals is suggested. The pure rotational relaxation times and intermolecular torques acting on PAA molecules in nematic phase have been calculated from the experimental results.