Chemical Separation Method Research Articles

Physical and Chemical Properties and Crystal Structure Transformation of Beeswax during Heat Treatment

The object of research is the wax as a waste product of bees in the steppe and mountain areas of Almaty region of Kazakhstan. Purpose: To study the structure parameters and the homologous phase composition, morphology waxes of alpine and mountain areas of Kazakhstan and the establishment temperature-dependent patterns of their atomic-crystalline state. Methods: Radiography, gas chromatography, scanning electron microscopy and chemical methods of separation of multicomponent systems. The results were obtained in the atomic crystal and molecular structures of beeswax depending on the districts collecting materials. The technique of obtaining radiographs after dissolving beeswax in benzene, hexane and xylene was used. Submitted thermo-radiographic study samples were obtained. Batch analysis thermo-radiographs waxes after treatment with benzene, hexane and xylene showed that their structure is essentially different from the source and closer to the spectra of the crystallized wax melted and due to annihilation of stacking faults waxes native atoms after their dissolution in hexane, benzene and xylene and subsequent their recrystallization. The results obtained allow expanding the amount of information on the physico-chemical processes and structural transformations in beeswax as a composite of different genesis biomaterial. Scope: Beekeeping, plant, structural and analytical chemistry, biotechnology and biocomposites.

Validation of chemical separation method for the determination of 63Ni using TDCR technique in steel samples of APSARA reactor

Activity Standards of 63Ni was used to benchmark our triple-to-double coincidence ratio (TDCR) primary standardization instrument Hidex 300SL TDCR device under different chemical and colour quench conditions. The results were compared with a secondary standardization instrument Tricarb 2910TR that employs transformed spectral index of external standard to assess the quench level of samples. Excellent agreement was observed (within 3 %) for a wide range of standard activity and quench conditions. The method was subsequently used for validating chemical separation procedure for estimation of 63Ni in neutron activated standard nickel and steel samples. Further the method was applied for estimation of 63Ni from decommissioning waste of a research reactor, APSARA.

THEORETICAL MATTERS OF REVERSE OSMOSIS AND ADSORPTION AT PURIFICATING MULTICOMPONENT SOLUTIONS

Traditional modern chemical technology methods for solution and liquid mixture component separation are based on the difference between physical and chemical parameters of components being separated (boiling point, solubility). The methods use the phenomenon of phase change. Thus to install the equipment for the processes is quite complicated and power-consuming.As the world population grows we face new problems,i.e. the shortage of drinking water. Different methods are applied for getting drinking water such as distillation and freezing out. Half of all the desalinated water is got by distillation. To solve the arisen problems by using the traditional methods of chemical technology is becoming more and more complicated. Methods of membrane separation have turned out to be promising in this respect.

High‐resolution 3D radial bSSFP with IDEAL

Radial trajectories facilitate high-resolution balanced steady state free precession (bSSFP) because the efficient gradients provide more time to extend the trajectory in k-space. A number of radial bSSFP methods that support fat-water separation have been developed; however, most of these methods require an environment with limited B0 inhomogeneity. In this work, high-resolution bSSFP with fat-water separation is achieved in more challenging B0 environments by combining a 3D radial trajectory with the IDEAL chemical species separation method. A method to maintain very high resolution within the timing constraints of bSSFP and IDEAL is described using a dual-pass pulse sequence. The sampling of a unique set of radial lines at each echo time is investigated as a means to circumvent the longer scan time that IDEAL incurs as a multiecho acquisition. The manifestation of undersampling artifacts in this trajectory and their effect on chemical species separation are investigated in comparison to the case in which each echo samples the same set of radial lines. This new bSSFP method achieves 0.63 mm isotropic resolution in a 5-min scan and is demonstrated in difficult in vivo imaging environments, including the breast and a knee with ACL reconstruction hardware at 1.5 T.

Performance of chemical shift-based water-fat separation with self-calibrated fat spectrum is sensitive to echo times

Chemical shift-based water-fat separation method utilises water-fat resonance frequency difference to decompose signals into water and fat partitions in magnetic resonance imaging (MRI) on a pixel-wise basis. It provides an effective way to measure fat fraction, or to suppress fat signal which might obscure underlying pathology. IDEAL (Iterative decomposition of water and fat with echo asymmetry and least-squares estimation) algorithm with multi-peak fat spectral modelling has been developed. Recent studies have discussed the performance of this algorithm assuming that the frequencies and relative amplitudes of fat peaks are constant among all subjects. However, the fat spectra vary in different tissues, thus a self-calibration method which estimates the fat spectrum directly from the data provides more accurate results. In this work, we analyse the performance of multi-peak IDEAL algorithm with self-calibrated fat spectrum by theoretical calculation, simulation, and experiments, and find optimal echo time increments which provide reliable water-fat separation.

Separation and Purification of ε-Poly-L-lysine from the Culture Broth Based on Precipitation with the Tetraphenylborate Anion

A biopolymer ε-poly-L-lysine (εPL) exists as a fully protonated form (εPLH(n+)) in solutions at pH < 4. Around pH 3.5, at which the tetraphenylborate (TPB(-)) anion is not decomposed immediately, the εPLH(n+) cation associates with the TPB(-) anion to form a precipitate of 1:n stoichiometry, εPLH(TPB)(n). By the addition of NaTPB to a culture broth containing εPL and NH(4)(+) and K(+) ions, not only the polycationic εPLH(n+) but also the monovalent cations would be precipitated with the TPB(-) anion. However, εPLH(TPB)(n) was purified by washing the mixed precipitate with acetone, in which NH(4)TPB and KTPB are soluble. By mixing the εPLH(TPB)(n) precipitate and a high-concentration HCl solution, the TPB(-) anion was decomposed immediately to hydrophobic molecules. By the addition of a much larger volume of acetone to the reaction mixture, the decomposition products dissolved in the solvent. Simultaneously, εPL was precipitated as the hydrochloride salt. Thus, εPL has been separated and purified from the culture broth. Also, the method has been successfully applied to the separation of oligomeric εPL species. The present chemical separation method is rapid, simple, and easy to carry out, and can be utilized in bioengineering studies of such basic peptides or polyamines.

Analysis and environmental application of 129I at the Xi’an Accelerator Mass Spectrometry Center

The newly established 3MV Accelerator Mass Spectrometry (AMS) facility in Xi’an, with an instrument background of 2×10−14 for 129I/127I ratio, provides efficient analytical capability to carry out 129I environmental tracing studies. Chemical separation methods of iodine from different types of samples have been established at the Xi’an AMS Center, including solvent extraction and combustion followed by extraction or coprecipitation depending on sample types. A carrier free method for iodine separation and AMS measurement of ultra low level 129I in samples with low total iodine concentration has been established, which can be used for analysis of geological samples for 129I dating. Some environmental samples collected in China have been analyzed using the developed methods. The analytical results show 129I/127I ratios of (0.9–1.1)×10−10 for seawater collected adjacent to a nuclear power plant, and (3.02–5.43)×10−10 for soil samples collected in a less than 10km area surrounding the NPP. These values are not significantly different from those measured in remote areas, reflecting a safe nuclear environment in terms of 129I level.

Progress on 129I analysis and its application in environmental and geological researches

Iodine-129 is a naturally generated isotope, but anthropogenic releases are the dominated source of 129I in the present environment. Among many measurement techniques, neutron activation analysis (NAA) and accelerator mass spectrometry (AMS) are only methods used for measurement of 129I in environmental level. Based on its source terms, chemical properties and environmental behaviors, 129I can be applied for geological dating in a range of 2–80Ma, investigation of formation and migration of hydrocarbon, circulation of ocean water, atmospheric process of iodine, as well as reconstruction of dispersion and migration of short-lived radioisotopes of iodine released from nuclear accidents. This article aims to summarize and critically compare the analytical techniques used for 129I measurement and chemical methods for separation of iodine from various sample matrices, purification from the interferences, as well as preparation of suitable target for AMS measurement. The major applications in environmental and geological researches are reviewed, which mainly focus on the new progress and potential development in the future. The application of 129I in the investigation of radioactive contamination from the Fukushima accident is discussed.

Studies of total, organic and inorganic iodine in Canadian bovine milk samples with varying milk fat content using ion-exchange chromatography and neutron activation analysis

Chemical separation methods in conjunction with instrumental neutron activation analysis (INAA) were developed for measuring iodine levels in commercially available bovine milk with varying milk fat (MF) content. Samples of homogenized (3.25 % MF), partly skimmed (2 % MF), partly skimmed (1 % MF), partly skimmed calcium enriched (1 % MF + Ca), and skim (<0.05 %) milk were purchased from local supermarkets. Ion exchange chromatography, solvent extraction, and ammonium sulfate precipitation methods were applied to the separation of the inorganic, lipidic and proteic fractions of iodine in milk. The levels of iodine were measured by INAA in total reactor and epi-cadmium (EINAA) neutron flux in conjunction with conventional gamma-ray and Compton suppression spectrometry (CSS). A pseudo-cyclic INAA method coupled with CSS (PC-INAA-CSS) was also explored as an instrumental option to further lower the detection limit of iodine. The detection limits of 0.06, 0.06 and 0.02 μg mL−1 for iodine were obtained using INAA-CSS, EINAA-CSS, and PC-INAA-CSS methods, respectively. Although the PC-INAA-CSS method provided the lowest detection limit, the INAA-CSS method was sufficient for the determination of total iodine in almost all samples analyzed in this work. The total iodine concentrations (μg mL−1) were: 0.40 ± 0.01 (in 3.25 % MF), 0.40 ± 0.01 (2 % MF), 0.42 ± 0.01 (1 % MF), 0.42 ± 0.01 (<0.05 %), and 0.96 ± 0.01 (1 % MF + Ca) milk samples. Iodine bound to various fractions of the milk samples analyzed, in percent of total iodine content, ranged: (0.05–1.8), (1.9–4.8), (90–95) for the lipidic, proteic and anionic inorganic fractions respectively. Iodine recovery in all cases was higher than 96 %.

Chemical Shift MR Imaging Methods for the Quantification of Transcatheter Lipiodol Delivery to the Liver: Preclinical Feasibility Studies in a Rodent Model

To demonstrate the feasibility of using chemical shift magnetic resonance (MR) imaging fat-water separation methods for quantitative estimation of transcatheter lipiodol delivery to liver tissues. Studies were performed in accordance with institutional Animal Care and Use Committee guidelines. Proton nuclear MR spectroscopy was first performed to identify lipiodol spectral peaks and relative amplitudes. Next, phantoms were constructed with increasing lipiodol-water volume fractions. A multiecho chemical shift-based fat-water separation method was used to quantify lipiodol concentration within each phantom. Six rats served as controls; 18 rats underwent catheterization with digital subtraction angiography guidance for intraportal infusion of a 15%, 30%, or 50% by volume lipiodol-saline mixture. MR imaging measurements were used to quantify lipiodol delivery to each rat liver. Lipiodol concentration maps were reconstructed by using both single-peak and multipeak chemical shift models. Intraclass and Spearman correlation coefficients were calculated for statistical comparison of MR imaging-based lipiodol concentration and volume measurements to reference standards (known lipiodol phantom compositions and the infused lipiodol dose during rat studies). Both single-peak and multipeak measurements were well correlated to phantom lipiodol concentrations (r(2) > 0.99). Lipiodol volume measurements were progressively and significantly higher when comparing between animals receiving different doses (P < .05 for each comparison). MR imaging-based lipiodol volume measurements strongly correlated with infused dose (intraclass correlation coefficients > 0.93, P < .001) with both single- and multipeak approaches. Chemical shift MR imaging fat-water separation methods can be used for quantitative measurements of lipiodol delivery to liver tissues.

Recent developments in nuclear data measurements and chemical separation methods in accelerator production of astatine and technetium radionuclides

AbstractThe cyclotron produced neutron deficient technetium radionuclides (93Tc,94(m+g)Tc,95Tc,96Tc) have gained renewed interest in various fields, including nuclear imaging, provided they can be obtained in a pure form. Similarly,211At due to its moderate half-life and high intensityα-particle energy (both from211At as well as its transient decay product211Po) is of prime interest in targeted therapy. Another interest is to study the astatine chemistry, which is least studied compared to other halogens due to its non-occurrence in natural systems. For maximum production of these radionuclides various parameters need to be standardized. A chemical separation is required to achieve high radiochemical purity beforein-vivoapplication. This review describes various production routes of neutron deficient astatine and technetium radionuclides that have been reported after the year 2000. The analytical chemistry developed for separation of no-carrier-added (nca) Tc and At radionuclides in the same period is also discussed in detail.

Validation of MRI biomarkers of hepatic steatosis in the presence of iron overload in the ob/ob mouse

To validate the utility and performance of a T 2 correction method for hepatic fat quantification in an animal model of both steatosis and iron overload. Mice with low (n = 6), medium (n = 6), and high (n = 8) levels of steatosis were sedated and imaged using a chemical shift-based fat-water separation method to obtain magnetic resonance imaging (MRI) fat-fraction measurements. Imaging was performed before and after each of two superparamagnetic iron oxide (SPIO) injections to create hepatic iron overload. Fat-fraction maps were reconstructed with and without T 2 correction. Fat-fraction with and without T 2 correction and T 2 measurements were compared after each injection. Liver tissue was harvested and imaging results were compared to triglyceride extraction and histology grading. Excellent correlation was seen between MRI fat-fraction and tissue-based fat quantification. Injections of SPIOs led to increases in R 2 (=1/T 2). Measured fat-fraction was unaffected by the presence of iron when T 2 correction was used, whereas measured fat-fraction dramatically increased without T 2 correction. Hepatic fat-fraction measured using a T 2-corrected chemical shift-based fat-water separation method was validated in an animal model of steatosis and iron overload. T 2 correction enables robust fat-fraction estimation in both the presence and absence of iron, and is necessary for accurate hepatic fat quantification.

89Zr radiochemistry for positron emission tomography.

The positron emitting isotope (89)Zr is an ideal radionuclide for use in positron emission tomography (PET) imaging with monoclonal antibodies (mAbs). This article reviews the cyclotron physics of (89)Zr production, and the chemical separation methods for isolating it from yttrium target material. (89)Zr coordination with the bifunctional chelate desferrioxamine B is discussed, along with the common procedures for attaching the chelate to mAbs. The review is intended to detail the procedure for creating (89)Zr labeled mAbs, going from cyclotron to PET.

High-Precision Measurement of Variations in Calcium Isotope Ratios in Urine by Multiple Collector Inductively Coupled Plasma Mass Spectrometry

We describe a new chemical separation method to isolate Ca from other matrix elements in biological samples, developed with the long-term goal of making high-precision measurement of natural stable Ca isotope variations a clinically applicable tool to assess bone mineral balance. A new two-column procedure utilizing HBr achieves the purity required to accurately and precisely measure two Ca isotope ratios ((44)Ca/(42)Ca and (44)Ca/(43)Ca) on a Neptune multiple collector inductively coupled plasma mass spectrometer (MC-ICPMS) in urine. Purification requirements for Sr, Ti, and K (Ca/Sr > 10 000; Ca/Ti > 10 000 000; and Ca/K > 10) were determined by addition of these elements to Ca standards of known isotopic composition. Accuracy was determined by (1) comparing Ca isotope results for samples and standards to published data obtained using thermal ionization mass spectrometry (TIMS), (2) adding a Ca standard of known isotopic composition to a urine sample purified of Ca, and (3) analyzing mixtures of urine samples and standards in varying proportions. The accuracy and precision of δ(44/42)Ca measurements of purified samples containing 25 μg of Ca can be determined with typical errors less than ±0.2‰ (2σ).

Analytical methods for the determination of pesticide residues using gas chromatograghy with nitrogen-phosphorus detector

The analysis methods for 3 pesticides (ametryn, cyanophos, and fonofos) were developed and validated. One 1,3,5-triazine herbicide (ametryn), and 2 organophosphorus insecticides (cyanophos and fonofos) were tested. Three kinds of residual pesticides were classified into 2 groups according to the chemical structure and separation method. Solid-phase extraction (SPE) cartridge was used for sample purification and isolation of analytes. Final solution was analyzed with GC with nitrogen-phosphorus detection (NPD). Confirmation analysis of pesticides was carried out by GC-MS in the selected ion monitoring (SIM) mode. Correlation coefficient was ranged from 0.999 to 1.0, depending on sample analytes. Rice, apple, and soybean samples were selected for recovery experiment. Overall recovery rates from blank samples spiked at 3 fortification levels ranged from 76.29 to 107.4% with relative standard deviations lower than 20.2%. The limit of quantification was <3–5 μg/L depending on the analytes, and the reporting level of the method, defined as lower than the maximum residue levels established by Korea Food & Drug Administration (KFDA).

T1 independent, T2* corrected chemical shift based fat–water separation with multi‐peak fat spectral modeling is an accurate and precise measure of hepatic steatosis

To determine the precision and accuracy of hepatic fat-fraction measured with a chemical shift-based MRI fat-water separation method, using single-voxel MR spectroscopy (MRS) as a reference standard. In 42 patients, two repeated measurements were made using a T(1) -independent, T 2*-corrected chemical shift-based fat-water separation method with multi-peak spectral modeling of fat, and T(2) -corrected single voxel MR spectroscopy. Precision was assessed through calculation of Bland-Altman plots and concordance correlation intervals. Accuracy was assessed through linear regression between MRI and MRS. Sensitivity and specificity of MRI fat-fractions for diagnosis of steatosis using MRS as a reference standard were also calculated. Statistical analysis demonstrated excellent precision of MRI and MRS fat-fractions, indicated by 95% confidence intervals (units of absolute percent) of [-2.66%,2.64%] for single MRI ROI measurements, [-0.81%,0.80%] for averaged MRI ROI, and [-2.70%,2.87%] for single-voxel MRS. Linear regression between MRI and MRS indicated that the MRI method is highly accurate. Sensitivity and specificity for detection of steatosis using averaged MRI ROI were 100% and 94%, respectively. The relationship between hepatic fat-fraction and body mass index was examined. Fat-fraction measured with T(1) -independent T 2*-corrected MRI and multi-peak spectral modeling of fat is a highly precise and accurate method of quantifying hepatic steatosis.

Compressed sensing for chemical shift‐based water–fat separation

Multi echo chemical shift-based water-fat separation methods allow for uniform fat suppression in the presence of main field inhomogeneities. However, these methods require additional scan time for chemical shift encoding. This work presents a method for water-fat separation from undersampled data (CS-WF), which combines compressed sensing and chemical shift-based water-fat separation. Undersampling was applied in the k-space and in the chemical shift encoding dimension to reduce the total scanning time. The method can reconstruct high quality water and fat images in 2D and 3D applications from undersampled data. As an extension, multipeak fat spectral models were incorporated into the CS-WF reconstruction to improve the water-fat separation quality. In 3D MRI, reduction factors of above three can be achieved, thus fully compensating the additional time needed in three-echo water-fat imaging. The method is demonstrated on knee and abdominal in vivo data.

Noninvasive temperature mapping with MRI using chemical shift water‐fat separation

Tissues containing both water and lipids, e.g., breast, confound standard MR proton reference frequency-shift methods for mapping temperatures due to the lack of temperature-induced frequency shift in lipid protons. Generalized Dixon chemical shift-based water-fat separation methods, such as GE's iterative decomposition of water and fat with echo asymmetry and least-squares estimation method, can result in complex water and fat images. Once separated, the phase change over time of the water signal can be used to map temperature. Phase change of the lipid signal can be used to correct for non-temperature-dependent phase changes, such as amplitude of static field drift. In this work, an image acquisition and postprocessing method, called water and fat thermal MRI, is demonstrated in phantoms containing 30:70, 50:50, and 70:30 water-to-fat by volume. Noninvasive heating was applied in an Off1-On-Off2 pattern over 50 min, using a miniannular phased radiofrequency array. Temperature changes were referenced to the first image acquisition. Four fiber optic temperature probes were placed inside the phantoms for temperature comparison. Region of interest (ROI) temperature values colocated with the probes showed excellent agreement (global mean +/- standard deviation: -0.09 +/- 0.34 degrees C) despite significant amplitude of static field drift during the experiments.

K‐space water‐fat decomposition with T2* estimation and multifrequency fat spectrum modeling for ultrashort echo time imaging

To demonstrate the feasibility of combining a chemical shift-based water-fat separation method (IDEAL) with a 2D ultrashort echo time (UTE) sequence for imaging and quantification of the short T(2) tissues with robust fat suppression. A 2D multislice UTE data acquisition scheme was combined with IDEAL processing, including T(2)* estimation, chemical shift artifacts correction, and multifrequency modeling of the fat spectrum to image short T(2) tissues such as the Achilles tendon and meniscus both in vitro and in vivo. The integration of an advanced field map estimation technique into this combined method, such as region growing (RG), is also investigated. The combination of IDEAL with UTE imaging is feasible and excellent water-fat separation can be achieved for the Achilles tendon and meniscus with simultaneous T(2)* estimation and chemical shift artifact correction. Multifrequency modeling of the fat spectrum yields more complete water-fat separation with more accurate correction for chemical shift artifacts. The RG scheme helps to avoid water-fat swapping. The combination of UTE data acquisition with IDEAL has potential applications in imaging and quantifying short T(2) tissues, eliminating the necessity for fat suppression pulses that may directly suppress the short T(2) signals.

Focal iron sparing and focal fat sparing of liver in patients with hemosiderosis: diagnosis by combination of r2* relaxometry and fat fraction calculation by mri.

To demonstrate magnetic resonance imaging (MRI) findings of the focal sparing of iron and fat in liver tissue in patients with hepatic iron overload. We retrospectively reviewed 48 liver MRIs performed in patients with hemosiderosis from 2007-2009. We selected five (10%) of these patients based on the observation of focal signal abnormalities in the posterior aspect of segment 4, anterior to the portal vein, on in- and out-of-phase T1-weighted gradient-echo images. To further characterize this signal abnormality in segment 4, we calculated the simultaneous proton density fat fraction and R2* relaxometry using the investigational version of a quantitative chemical shift-based water-fat separation method known as IDEAL-IQ with a multiecho gradient echo sequence. Visual assessment and objective measurements were performed for the focal sparing of iron and fat. The diagnoses of the five patients included thalassemia (n=3), aplastic anemia (n=1), and myelodosysplastic syndrome (n=1). The focal sparing of iron was hypointense on R2* relaxometry compared to the rest of the liver. Fat fraction images failed to demonstrate a heterogeneous fat distribution. The focal sparing of fat in the liver with iron overload appeared as a reduced fat-containing area (fat fraction, 4%) in segment 4 compared to the remainder of the left lobe (fat fraction, 12%). The R2* map revealed no difference between the focal fat-sparing area and the rest of the liver. Areas in which focal fat and iron sparing occurred were not visible on post-contrast and diffusion-weighted images. Focal fat and iron sparing in patients with liver siderosis can mimic a lesion. Quantitative MRI techniques can help to characterize abnormal signal changes in segment 4 of the liver in patients with hepatic iron overload and can eliminate the need for biopsy of pseudolesions.