Separation Column Research Articles

Development of a system for controlling the temperature field of the columns and pipelines of raw gas transportation

With the formation of high-precision production processes, manufacturers are faced with the issue of the need to develop high-precision, high-tech regulators. In the development of the oil and gas industry, this is especially noticeable. Inaccuracy of high-precision control of field equipment requires high-quality regulation of the preparation process of gas transportation and running-in. In the given scientific research the collective of authors considers process of a temperature field regulation of the field gas equipment. Approaches to modeling of gas equipment are analyzed. Mathematical model of separating column heater is built. The system of controlling the temperature field of the separation column on the basis of pulse sectional heaters is developed. This work is a continuation of the authors’ team-work aimed at improving the technology of production, transportation and development of crude gas.

Controllably Adjusting the Hydrophobicity of Collagen Fibers for Enhancing the Adsorption Rate, Retention Capacity, and Separation Performance of Flavonoid Aglycones.

Collagen fibers (CFs) were previously used as packing materials for the separation of flavonoids based on hydrogen bond and hydrophobic interactions. However, as for flavonoid aglycones, CFs presented unsatisfactory adsorption capacity and separation efficiency due to the fact that they include limited hydroxyls and phenyls. In order to improve the adsorption capacity and separation efficiency, the hydrophobic modification strategy was employed in this research to enhance the hydrophobic interaction of CF with flavonoid aglycones by using silane coupling agents with different alkyl chains (isobutyl, octyl, and dodecyl). FT-IR analysis, DSC, TG, SEM, EDS mapping, water contact angle, and absorption time of solvent proved the successful grafting of alkyl chains on the CF without disturbing its special fiber structure, leading to the significantly enhanced hydrophobicity of the CF. The dynamic adsorption and elution behavior of kaempferol and quercetin (the typical flavonoid aglycones) on the hydrophobic CF showed that the adsorption rate and retention rate were largely increased in comparison with the CF without modification. Molecular dynamic simulations indicated that the CF grafted with isobutyls could interact with flavonoid aglycones through the highest synergetic effect of hydrophobic and hydrogen bond interactions, which exhibited the strongest retention to flavonoid aglycones. On further increasing the alkyl length (octyl and dodecyl), the hydrophobic interaction was further enhanced, but the hydrogen bonds were significantly weakened by steric hindrance, which showed that the retention to flavonoid aglycones was appropriately increased but without causing peak tailing. In the column separation of kaempferol and quercetin, the CF with hydrophobic modification presented a greater separation efficiency, with the purity of kaempferol increased from 71.99 to 86.57-97.50% and the purity of quercetin increased from 82.69 to 88.07-99.37%, which was much better than that of polyamide and close to that of sephadex LH 20. Therefore, the hydrophobicity of the CF could be controllably adjusted to enhance the adsorption rate and retention capacity, specifically improving the separation efficiency of flavonoid aglycones.

Determination of Cations and Anions in Desulfurization Waste Water of Coal-Fired Power Plant by Ion Chromatography.

The reliable and accurate determination of corrosive anions at sub- to low-μg/L levels is a challenging analytical problem. In this manuscript, a simultaneous determination method of cations and anions in power plant water samples was established by large volume injection ion chromatography. The analytical parameters including separation column, the suppressor current and the elute concentration were optimized. Results showed good separation under the optimum conditions, and the calibration curves of all analytes were linear with good coefficient of determination (r2) >0.997, and the mean recoveries for all analytes ranged from 75.62 to 118.58% with RSD of 0.07-4.83%. The established method was successfully applied to determine the cations and anions in realwaste water samples from coal-fired power, and was verified by inductively coupled plasma optical emission spectrometry and electrometric titration. The relative deviation between methods was all below 6.72%, which indicated good accuracy of the established ion chromatography method. The results could also provide reference for the precise and rapid detection of cations and anions in environmental water samples.

The oil bath thermal cycling absorption process design and separation process research

Thermal cycling absorption process (TCAP) has been developed for years to support the separation of hydrogen isotopes, which has the characteristics of high separation efficiency and high recovery rate. The design of separation column structure, heating and cooling (H&C) system and technological parameters are the basis of TCAP technical process study and are the key points of TCAP engineering research. In this work, an improved separation system has been designed and built based on an oil bath H&C system for the first time. The separation column in this facility is 45 m long and the packing weight in the column is up to 8 kg. The separation experiments were carried out based on this facility, and the process parameters were adjusted according to the size of the separation column, which proved the superior performance of this facility. The separation experiments show that for 50% D2 - 50% H2 feed gas, the deuterium abundance can reach to 99% and the steady state extraction can be realized in production mode with the processing capacity over 400 standard L per day. Another experiment has been carried out with 1% D2 - 99% H2 feed gas, and the deuterium abundance exceeded 10%, verifying the separation ability at low abundance deuterium feed gas. Furthermore, the extraction rate can reach to 25% column capacity when the deuterium abundance in production gas is 5%.

Mitoxantrone Quantification by HPLC-MS/MS in Caco-2 Culture Media

Mitoxantrone is a marker substrate of breast cancer resistance protein (BCRP). BCRP is involved in a number of pharmacokinetic drug-drug interactions. The transporter’s possible saturability makes it advisable to use low concentrations of mitoxantrone for in vitro studies. Consequently, mitoxantrone quantification requires a method with high sensitivity.The aim of the study was to develop and validate a procedure for mitoxantrone quantification in Caco-2 culture media by HPLC-MS/MS.Materials and methods. The authors used an Ultimate 3000 HPLC system and a TSQ Fortis triple quadrupole mass spectrometer by Thermo Fisher Scientific and a Selectra C18 column (4.6×100 mm, 5 μm, 100 Å) by United Chemical Technologies. The elution ran in a gradient mode with a mobile phase of 1% formic acid solution and methanol. Experimental parameters were as follows: eluent flow rate, 0.3 mL/min; separation column temperature, 35 °C; injection volume, 5 μL; ana lysis time, 10 min; approximate mitoxantrone retention time, 5.51 min. The sample preparation involved protein precipitation from the culture medium with methanol, followed by centrifugation at 13,000 g for 10 min. The detection was performed using electrospray ionisation in the positive ion mode. Detection parameters were as follows: electrospray voltage, 3700 V; sheath gas flow rate, 50 L/min; auxiliary gas flow rate, 10 L/min; sweep gas flow rate, 1 L/min; ion-transfer tube temperature, 300 °C; and evaporator temperature, 350 °C. The detection was set at mass transitions of m/z 455 to 88.2 and m/z 455 to 358.1, with the collision energy for these transitions amounting to 25 V and 18 V, respectively. The source fragmentation was at 0, and the CID gas pressure was at 2 mTorr.Results. The analytical procedure showed selectivity, high sensitivity (limit of detection, 10 nmol/L; lower limit of quantification, 50 nmol/L), accuracy, precision, and linearity in the concentration range of 50–1000 nmol/L. The authors observed no carryover or matrix effects. A simulation of real-life storage conditions demonstrated high stability of mitoxantrone samples. Thus, the analytical procedure enables preclinical evaluation of medicinal product effects on the functional activity of BCRP, based on assessing the transcellular mitoxantrone transport in the presence of a test product.Conclusion. The authors developed and validated the analytical procedure for mitoxantrone quantification in Caco-2 culture media by HPLC-MS/MS.

Continuous protein refolding and purification by two-stage periodic counter-current chromatography

Matrix-assisted refolding (MAR) has been used as an alternative to conventional dilution-based refolding to improve recovery and reduce specific buffer consumption. Size exclusion chromatography (SEC) has been extensively used for MAR because of its ability to load and refold proteins at high concentrations. However, the SEC-based batch MAR processes have the disadvantages of requiring longer columns for better separation and product dilution due to a high column-to-sample volume ratio. In this work, a modified operational scheme is developed for continuous MAR of L-asparaginase inclusion bodies (IBs) using SEC-based periodic counter-current chromatography (PCC). The volumetric productivity of the modified SEC-PCC process is 6.8-fold higher than the batch SEC process. In addition, the specific buffer consumption decreased by 5-fold compared to the batch process. However, the specific activity of the refolded protein (110–130 IU/mg) was less due to the presence of impurities and additives in the refolding buffer. To address this challenge, a 2-stage process was developed for continuous refolding and purification of IBs using different matrices in sequential PCCs. The performance of the 2-stage process is compared with literature reports on single-stage IMAC-PCC and conventional pulse dilution processes for refolding L-asparaginase IBs. The 2-stage process resulted in a refolded protein with enhanced specific activity (175–190 IU/mg) and a high recovery of 84%. The specific buffer consumption (6.2 mL/mg) was lower than the pulse dilution process and comparable to the single-stage IMAC-PCC. A seamless integration of the two stages would considerably increase the throughput without compromising other parameters. High recovery, throughput, and increased operational flexibility make the 2-stage process an attractive option for protein refolding.

End-modification of poly(ether-carbonate) copolymer by adamantane cages: An effective approach for improving the selectivity of gas chromatographic stationary phases

This work reports the investigation of a new poly(propylene-carbonate) copolymer terminated by the adamantane cages (APPC) as the stationary phase for gas chromatographic (GC) analyses. In GC, the selectivity of a stationary phase is the key factor that governs the column separation performance for analytes, particularly those of high similarity in structures and properties. As such, we employed more than a dozen of isomer mixtures of separation difficulty for investigating the separation performance of the APPC column, involving the isomers of alkanes, alkylbenzenes, halobenzenes phenols and anilines. Meanwhile, the column coated with poly(propylene carbonate) diol (PPCD) differing from APPC only in their terminal groups and two commercial columns coated with polyethylene glycol (PEG) and polysiloxane, respectively, were used as the reference columns. The separation results evidenced the distinctly advantageous performance of the APPC column over the reference columns. Moreover, the APPC column showed excellent repeatability and reproducibility with the relative standard deviation (RSD) values over the range of 0.01%–0.04% for run-to-run, 0.15%–0.28% for day-to-day and 3.4%–3.9% for column-to-column (n = 4). Its application to GC–MS analysis of the verbena essential oil demonstrated its separation advantages for a wide range of components in practical samples. Up to date, the adamantyl-terminated poly(ether-carbonate) copolymers have not been reported in any fields. Its high-resolution performance demonstrates the feasibility of adamantyl-terminated block copolymers as highly selective stationary phases for GC analyses, which offers a vast room for fundamental researches and applications.

Highly efficient and selective recovery of Au(III) by cellulose microspheres bearing nucleobase and their applications in gold slag treatment

Gold recovery from secondary resources involves tremendous environmental and economic implications. In this work, four nucleobase (guanine, xanthine, hypoxanthine and adenine) modified cellulose microspheres were synthesized via radiation method for Au(III) capture from actual gold slag solution. The adsorption rapidly achieved equilibrium within 4 h. It was discovered that the pseudo-second-order and Langmuir model provided a superior match for the Au(III) adsorption process on adsorbents. At the optimal pH, the four adsorbents exhibited the outstanding adsorption capacities for Au(III) with a range of 307.69–510.20 mg/g. Furthermore, cellulose microspheres bearing nucleobase were able to selectively adsorb trace Au(III) with recovery efficiencies of 62 %–70 % from gold slag leaching solution. In addition, the column separation approach was utilized to better assess the applicability of adsorbents, proving that cellulose microspheres bearing nucleobase exhibited great benefits and prospects in industrial applications. The N-containing groups on adsorbents captured Au(III) by ion exchange, chelation and oxidation–reduction. The low-cost nucleobase-bearing adsorbents offer a new prospect for nucleobase in environmental remediation and water treatment.

An Amphiphilic Star-Shaped Polymer (Star-PEG-PCL2) used as a Stationary Phase for GC.

A star-shaped polymer (Star-PEG-PCL2) was synthesized with PCL and PEG and used as a stationary phase for gas chromatography. The statically coated Star-PEG-PCL2 column exhibited an efficiency of 2260 plates/m determined by naphthalene at 120 °C and moderate polarity. The Star-PEG-PCL2 column showed high resolution performance for isomers of a wide ranging polarity, including methylnaphthalenes, halogenated benzenes, nitrobenzene, phenols, and anilines, and displayed dual-nature selectivity for a mixture of 17 analytes. Also, the Star-PEG-PCL2 column exhibited good separation performance and column inertness for Grob test mixture and a series of cis-/trans-isomers. In addition, it exhibited advantageous separation performance over the commercial HP-35 and PEG-20M columns for chloroaniline and bromoaniline isomers through its unique three-dimensional framework. In conclusion, it has good potential as a new stationary phase for separating a variety of analytes because of its special structure and excellent separation performance.

Treatment of surfactant wastewater by foam separation: Combining the RSM method and WOA-BP neural network to explore optimal process conditions

In the field of water treatment, the treatment of wastewater containing surfactants has been an important issue. The foam separation technique is often used to separate surfactants from water as a simple and efficient separation technique. We used a newly designed foam separation column to treat wastewater containing sodium dodecyl sulfonate (SDS) (0.5–2.0 mmol/L). The effects of initial SDS concentration (CSDS, i), operation time (t), foam height (H), gas velocity (V) and pH value (1−7) on the separation effect of SDS were investigated. The Box-Behnken design model was used to design the experimental group, and the process parameters of foam separation were optimized by combining response surface methodology (RSM) and WOA-BP neural network. The results showed that the prediction accuracy of the optimized BP neural network using the WOA algorithm was superior to that of the RSM model. The best operating parameters were: CSDS,i (0.88 mmol/L), t (28.13 min), H( 81.3 cm), V (1.03 L/min) and pH (3.5) and the recovery rate of SDS was up to 97.32%.

Development of tandem-column liquid chromatographic methods for pharmaceutical compounds using simulations based on hydrophobic subtraction model parameters

The liquid chromatography (LC) analysis of small molecule pharmaceutical compounds and related impurities is crucial in the development of new drug substances, but developing these separations is usually challenging due to analyte structural similarities. Tandem-column LC (TC-LC) has emerged as a powerful approach to achieve alternative separation selectivity compared to conventional single column separations. However, one of the bottlenecks associated with use of tandem column approaches is time-consuming column pair screening and selection. Herein, we compared critical resolution (Rc) in single column vs. TC-LC separations for a given set of small molecule pharmaceutical compounds and developed a column selection workflow that uses separation simulations based on parameters from the hydrophobic subtraction model (HSM) of reversed-phase selectivity.In this study, HSM solute parameters were experimentally determined for a small molecule pharmaceutical (Linrodostat) and ten of its related impurities using multiple linear regression of their retentions on 16 selected RPLC columns against in-house determined HSM column parameters. Rc values were calculated based on HSM database column parameters for a pool of about 200 available stationary phases in both single-phase column (2.1 mm i.d. × 100 mm) or tandem column paired (two 2.1 mm i.d. × 50 mm) formats. Four column configurations (two single and two tandem) were predicted to achieve successful separations under isocratic HSM separation conditions, with a fifth tandem pair predicted to have a single co-elution. Of these five potential candidates, one tandem pair yielded compete baseline resolution of the 11-component mixture in an experimental separation.In this specific case, the tandem column pairs outperformed single-phase columns, with better predicted and experimental Rc values for the Linrodostat mixture under the HSM separation conditions. The results reported in this study demonstrated the enormous selectivity potential of TC-LC in pharmaceutical compound separations and are consistent with our previous study that examined the potential of tandem column approaches using purely computational means, though there is room for substantial improvement in the prediction accuracy. The proposed workflow can be used to prioritize a small number of column combinations by computational means before any experiments are conducted. This is highly attractive from the point of view of time and resource savings considering over 200,000 different tandem column pairings are possible using columns for which there are data in the HSM database.

Recovery of Ammonium from Biomass-Drying Condensate Via Ion Exchange and Its Valorization as a Fertilizer

In this study, an industrial biomass-drying wastewater condensate containing > 3200 mg/L NH4+ and >8900 mg/L CH3COO− was treated in ion-exchange columns for the recovery of NH4+. Two commercial resins (CS12GC and CS16GC) were studied on laboratory and pilot scales. CS16GC outperformed CS12GC by achieving better separation at the condensate temperature (60 °C), which was energy-efficient regarding NH4+ removal. K3PO4 was used for regeneration to produce a liquid compound fertilizer containing nutrient elements (N, K, and P) as a byproduct. The N/K ratio in the byproduct was found to be adjustable by varying the operating parameters. Regeneration with 2 mol/L K3PO4 gave a higher regeneration efficiency (97.67% at 3 BV and ~100% at 4 BV). The stability tests performed on a laboratory scale showed that the cyclic runs of the column separation process were steady and repeatable. Based on the outcomes of the laboratory-scale tests, the pilot-scale tests applied a loading volume of 7 BV. The pilot column purified the feed and achieved the target NH4+ level in the treated effluent within the seven tested cycles, revealing that the industrial application of the cation ion-exchange resin CS16GC is worth further study.

A network community detection method with integration of data from multiple layers and node attributes

AbstractMultilayer networks are in the focus of the current complex network study. In such networks, multiple types of links may exist as well as many attributes for nodes. To fully use multilayer—and other types of complex networks in applications, the merging of various data with topological information renders a powerful analysis. First, we suggest a simple way of representing network data in a data matrix where rows correspond to the nodes and columns correspond to the data items. The number of columns is allowed to be arbitrary, so that the data matrix can be easily expanded by adding columns. The data matrix can be chosen according to targets of the analysis and may vary a lot from case to case. Next, we partition the rows of the data matrix into communities using a method which allows maximal compression of the data matrix. For compressing a data matrix, we suggest to extend so-called regular decomposition method for non-square matrices. We illustrate our method for several types of data matrices, in particular, distance matrices, and matrices obtained by augmenting a distance matrix by a column of node degrees, or by concatenating several distance matrices corresponding to layers of a multilayer network. We illustrate our method with synthetic power-law graphs and two real networks: an Internet autonomous systems graph and a world airline graph. We compare the outputs of different community recovery methods on these graphs and discuss how incorporating node degrees as a separate column to the data matrix leads our method to identify community structures well-aligned with tiered hierarchical structures commonly encountered in complex scale-free networks.

Effects of Addition of Tea Polyphenol Palmitate and Process Parameters on the Preparation of High-Purity EPA Ethyl Ester.

High-purity eicosapentaenoic acid (EPA) ethyl ester (EPA-EE) can be produced from an integrated technique consisting of saponification, ethyl esterification, urea complexation, molecular distillation and column separation. In order to improve the purity and inhibit oxidation, tea polyphenol palmitate (TPP) was added before the procedure of ethyl esterification. Furthermore, through the optimization of process parameters, 2:1 (mass ratio of urea to fish oil, g/g), 6 h (crystallization time) and 4:1 (mass ratio of ethyl alcohol to urea, g/g) were found to be the optimum conditions in the procedure of urea complexation. Distillate (fraction collection), 115 °C (distillation temperature) and one stage (the number of stages) were found to be the optimum conditions for the procedure of molecular distillation. With the addition of TPP and the above optimum conditions, high-purity (96.95%) EPA-EE was finally obtained after column separation.

Simultaneous determination of all aminobutyric acids by chiral derivatization and liquid chromatography-tandem mass spectrometry.

Aminobutyric acids include eight structural or stereoisomers that exhibit a wide range of biological activities. Recent evidence on some low abundant isomers have increased the demand for highly selective analysis of all the isomers; however, simultaneous separation of all the aminobutyric acid isomers has not been successful yet, except for a specialized method that uses multiple separation columns and a split of samples. In this study, we developed a new analytical method using chiral derivatization and liquid chromatography-tandem mass spectrometry to separate all the aminobutyric acid isomers in a single separation column. All the diastereomeric derivatives were resolved in a C18 column, and the derivatives showed characteristic fragmentation patterns in tandem mass spectrometry. By using the method, we analyzed the isomers in the Arabidopsis thaliana seeds and revealed the existence of three low abundant isomers, i.e., D-, L-β-aminoisobutyric acid, and D-β-aminobutyric acid. The proposed method uses a commercially available chiral derivatizing reagent and a broadly used column; therefore, it can be widely used in biological and food analyses.

Analysis of Free Pantothenic Acid in Foods by HPLC and LC-MS/MS

A simple and reliable analytical method has been developed for the determination of pantothenic acid in food. For the high-protein food, 20 mL of water was added to 2 g of sample, and after homogenization extraction, 1 mL of 15% zinc sulfate solution was added, mixed well, centrifuged, and the supernatant was filtered to make the test solution. For the low-protein food, 20 mL of 1% formic acid solution was added to 2 g of sample, homogenized, extracted, centrifuged, and the supernatant was filtered to make the test solution. The HPLC separation was carried out on a L-column2 ODS column with 0.02 mol/L phosphate solution (pH 3.0)- acetonitrile (95 : 5) as the mobile phase, and detected at 200 nm. The LC-MS/MS conditions were L-column2 ODS as the separation column, 5 mmol/L ammonium formate (containing 0.01% formic acid)-methanol (85 : 15) as the mobile phase, and multiple reaction monitoring (MRM) was used for detection. The recoveries of pantothenic acid in milk powder and nutritional food products were more than 88% with high precision. As a result of analyzing commetrcially available foods labeled as containing pantothenic acid, analytical values almost identical to the labeled values were obtained, and a high correlation was observed between the values obtained by HPLC and LC-MS/MS.

Evaluation of IMS drift tube temperature on the peak shape of high boiling fragrance compounds towards allergen detection in complex cosmetic products and essential oils

Gas chromatography-ion mobility spectrometry (GC-IMS) has recently gained increasing attention for the analysis of volatile compounds due to its high sensitivity, selectivity, and robust design. Peak shape distortion, including peak tailing or broadening, are well known challenges in chromatographic analysis that result in peak asymmetry and decreased resolution. However, in IMS analysis peak tailing, which is independent on the column separation technique, have also been observed. As high boiling substances, such as monoterpenes, are mainly affected by enlarged peak tailing in GC-IMS, we propose that condensation or adsorption effects within the “cold” IMS cell, which is commonly operated at 45 °C–90 °C, are the root cause. To avoid condensation and to decrease peak tailing, we used a prototypic high temperature ion mobility spectrometry (HTIMS) in this work, which allows an increase of the IMS drift tube temperature up to 180 °C. This HTIMS was coupled to a GC column separation and used to analyse the peak shape of homologues series of ketones, alcohols, aldehydes, as well as high boiling fragrance compounds, such as monoterpenes and phenylpropanoids. While we were able to show that an increased IMS drift tube temperatures correlates well with improved peak shapes, the GC parameters of the HS-GC-HTIMS method, however, were found to have little effect on the peak shapes in IMS spectra. In particular monoterpenes, which display intense peak tailing at lower IMS drift tube temperatures, show significant improvement of the peak shape at higher IMS drift tube temperatures. This leads to the assumption that high boiling substances indeed undergo condensation effects within the IMS cell at low drift tube temperatures. For many separation tasks, such as the separation of the phenylpropanoids eugenol and isoeugenol, comparably low IMS temperatures of 120 °C are already sufficient to achieve a resolution above 1.5. However, the optimal drift tube temperature is dependent on the substance class. While the aspect ratio increases steadily for most monoterpenes, phenylpropanoids and aldehyde monomer peaks investigated, an optimal aspect ratio was found for ketones between 140 °C and 160 °C and alcohols between 120 °C and 140 °C. Lastly, the change of the reduced mobility K0 with the increase of drift tube temperature was analysed. Compounds with similar chemical structure, such as the alcoholic monoterpenes citronellol and geraniol or the phenylpropanoids eugenol and isoeugenol show similar shifts of the K0 value. Substances which differ in their chemical structure, such as the aldehyde monoterpenes citral and cinnamal have substantially different shifts of the K0 value. With a future large substance database, the temperature dependant slope of the K0 value of a substance could be used to identify the substance groups of unknown molecules. Furthermore, substances with the same drift time but different chemical composition could be separable through a change in drift tube temperature.

Online micro solid phase extraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry for trace analysis of endogenous plant hormones in Ulva linza.

Ulva linza (L.) is a species of green algae widely distributed in China. We aimed to establish a sensitive online analytical method for quantification of endogenous phytohormones in fresh minute seaweed samples. The method for quantification of endogenous plant hormones in fresh minute samples was developed based on a homemade online micro solid phase extraction (m-SPE) system coupled with an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) platform. The online m-SPE instrument injected the eluent of m-SPE directly onto the LC separation column, improving the utilization of samples and saving time. The m-SPE column, of which the effective size was 9.6 × 2mm i.d., was filled with 19 mg of C18 (10μm). Under optimized conditions, the limits of detection were 0.002-0.060 ng ml-1 for five plant hormones. The actual sample recoveries of phytohormones were 76.4-103.4% and the coefficients of variance were below 14.1%. The temporal distribution of these endogenous plant hormones of U. linza during different growth periods is described. The proposed online m-SPE method was successfully applied to quantification of endogenous acidic and alkaline plant hormones in U. linza. It provides important information for the further study of the physiological and ecological effects of plant hormones in lower algal species.

Development of HPLC system that uses phase-separation multiphase flow as an eluent.

We developed a new type of HPLC system that uses phase-separation multiphase flow as an eluent. A commercially available HPLC system with a packed separation column filled with octadecyl-modified silica (ODS) particles was used. First, as preliminary experiments, 25 kinds of mixed solutions of water/acetonitrile/ethyl acetate and water/acetonitrile were supplied to the system to act as eluents at 20°C. 2,6-Naphthalenedisulfonic acid (NDS) and 1-naphthol (NA) mixture was used as a model and mixed analyte was injected into the system. Roughly speaking, they were not separated in organic solvent-rich eluents and well separated in water-rich eluents, in which NDS eluted faster than NA. This means that HPLC worked under a reverse-phase mode for separation at 20°C. Next, the separation of the mixed analyte was examined on HPLC at 5°C, and then after judging the results, four kinds of ternary mixed solutions were in detail as eluents on HPLC at 20°C and 5°C. Based on their volume ratio, the ternary mixed solutions acted as a two-phase separation mixed solution, leading to a phase-separation multiphase flow. Consequently, the solutions flowed homogeneously and heterogeneously in the column at 20°C and 5°C, respectively. For example, the ternary mixed solutions containing water/acetonitrile/ethyl acetate at volume ratios of 20:60:20 (organic solvent-rich) and 70:23:7 (water-rich) were delivered into the system as eluents at 20°C and 5°C. In the organic solvent-rich eluent, the mixture of NDS and NA was not separated at 20°C but was separated at 5°C, the elution of NA being faster than the one of NDS (phase-separation mode). In the water-rich eluent, the mixture of analytes was separated at both 20°C and 5°C, the elution of NDS being faster than the one of NA. The separation at 5°C was more effective than at 20°C (reverse-phase mode and phase-separation mode). This separation performance and elution order can be attributed to the phase-separation multiphase flow at 5°C.

Comparison of Designs of Hydrogen Isotope Separation Columns by Numerical Modeling

Mixtures of gas-phase hydrogen isotopologues (diatomic combinations of protium, deuterium, and tritium) can be separated using columns containing a solid such as palladium that reversibly absorbs hydrogen. A temperature-swing process can transport hydrogen into or out of a column by inducing temperature-dependent absorption or desorption reactions. We consider two designs: a thermal cycling absorption process, which moves hydrogen back and forth between two columns, and a simulated moving bed (SMB), where columns are in a circular arrangement. We present a numerical mass and heat transport model of absorption columns for hydrogen isotope separation. It includes a detailed treatment of the absorption–desorption reaction for palladium. By comparing the isotope concentrations within the columns as a function of position and time, we observe that SMB can lead to sharper separations for a given number of thermal cycles by avoiding the remixing of isotopes.