• Journal of Korean Society on Water Environment
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• v.22 no.5
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• pp.879-886
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• 2006

The analytical methods of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs) for water sample with extremely low concentration was developed to extract large volume and to improve fast chromatography for clean up. Semi-automated solid phase extraction (SPE) system and column coupling chromatography using elution pump was optimized and applied to each processes of treatment plant. Results of disk type SPE indicated that this system was applicable below 40 L of aqueous sample with a flow rate of 0.08 ~ 0.2 L/min. Average recoveries of SPE using labeled sampling spike of $^{37}Cl$-2,3,7,8-TCDD was 97%. Column coupling method resulted in reduced clean up time, solvent volume, increased average recoveries with constant elution rate. The combined methods were applied to the monitoring of drinking water treatment plant. Limits of detection (LOD) of each process were calculated. For example, LOD of raw and treated water ranged 0.094~0.968 pg/L and 0.028~0.364 pg/L, respectively. Combined methods of extraction and cleanup techniques provided fast analysis of PCDD/Fs with high accuracy and low LODs for water samples.

• Clean Technology
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• v.9 no.2
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• pp.81-85
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• 2003

A simple method of isotherm determination for HPLC is discussed. The equilibrium-dispersive model describing the behavior of elution peaks in HPLC for single component is solved numerically by using PDE solver Macsyma$^{(R)}$(Macsyma Inc., Arlington, MA, USA.) and compared to the experimental data obtained in overloaded isocratic chromatography with caffeine as model species. The effect of sample concentration and flow velocity on the band profiles of elution peaks are described.

• Journal of the Korean Chemical Society
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• v.45 no.3
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• pp.219-222
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• 2001

Separation of lithium isotopes was investigated by chemical ion exchange with a hydrous manganese(IV) oxide ion exchanger using an elution chromatography. The capacity of manganese(IV) oxide ion exchanger was 0.5 meq/g. The heavier lithium isotope was enriched in the solution phase, while the lighter isotope was enriched in the ion exchanger phase. The separation factor was determined according to the method of Glueckauf from the elution curve and isotopic assays. The separation factor of $^6Li^+$-$^7Li^+$ isotope pair fractionation was 1.018.

• Journal of the Korean Chemical Society
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• v.13 no.1
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• pp.37-40
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• 1969

The separation and species of $MoO_4^{--}$ and $WO_4^{--}$ at the various PH value have been studied by the method of cation exchange chromatography. Elution curves of $MoO_4^{--}$ and $WO_4^{--}$ have been made with a 5 cm column of the resin, $Dowe{\times}50W{\times}12$(100-200 mesh), using solutions of various PH value as eluent. Complete separation of $MoO_4^{--}$ and $WO_4^{--}$ was obtained in each PH of 10% EtOH. According to the evaluation of peak position and number of peaks of elution curves, it is likely to exist cationic species of $MoO_4^{--}$.

• Journal of the Korean Chemical Society
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• v.8 no.2
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• pp.62-64
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• 1964

The cation exchange chromatographic studies for the analysis of transition metals have been described. The quantitative separation of a mixture of Fe(Ⅲ), Cu(II), Zn(II), Ni(II), Cd(II), Co(II) and Mn(II) has been obtained by elution, through a 28cm column of the resin, Dowex 50 ${\times}$ 4 (100∼200 mesh), using 0.45 M $NaNO_3$+0.05 M Na-tartrate solution as eluent, starting with the eluent of pH 3.5, followed stepwise by pH 4.0 and 4.5. A comparison between the calculated and the observed peak positions in the elution curve has been shown. The relative stability constants for tartrate complexes of some transition metals have been calculated by using distribution ratios obtained in this separation procedure.

• FOCUS: LIFE SCIENCE
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• no.1
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• pp.9.1-9.5
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• 2024

Method development for complex low molecular mass (LMM) samples using reversed-phase (RP) separation conditions presents significant challenges due to the presence of many unknown analytes over wide concentration ranges. This guide aims to optimize method parameters-column length (L), temperature (T), flow rate (F), and final mobile phase conditions (Øfinal)-to maximize separation peak capacity. Validated by prior research, this protocol benefits laboratories dealing with metabolomics, natural products, and contaminant screening. This practical guide provides a structured approach to maximizing peak capacity for complex LMM separations. It complements computational optimization strategies and offers a step-by-step method development process. The Snyder-Dolan test is highlighted as essential for determining the need for gradient or isocratic elution and guiding column length decisions. The decision tree framework helps analysts prioritize variable optimization to develop effective separation methods for complex samples.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.7 no.1
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• pp.49-59
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• 1997

This study was performed to analyze the purity of technical grade ${\alpha}$-naphthylamine, to establish optimal analytical condition of ${\alpha}$-naphthylamine in urine and to determine the urine sample of workers exposed to ${\alpha}$-naphthylamine. The purity of technical grade ${\alpha}$-naphthylamine were $96.5{\pm}2.38%$, $94.1{\pm}0.97%$, $97.0{\pm}0.02%$ by gas chromatography-mass selective detector. To analyze ${\alpha}$-naphthylamine in urine, high performance liquid chromatography-electrochemical detector and gas chromatography-electron capture detector operating conditions have been optimized by preliminary expriment. In high performance liquid chromatography-electrochemical detector, the mobile phase was consisted of acetonitrile(35%) and water(65%), and the flow rate was maintained at 1.0ml per minute. Optimal detective condition was 9.0V(10nA/V) of electrochemical detector. The recovery of sep-pak treatment method was highly estimated as pretreatment of ${\alpha}$-naphthylamine in urine. The free amine was isolated by gas chromatography-electron capture detector after basic hydrosis, sep-pak treatment, toluene elution and HFBA(heptafluoro-butyric anhydride) derivatization of urine. The recovery of ${\alpha}$-naphthylamine in urine was $98.73{\pm}3.29%$ by gas chromatography-electron capture detector. The sensitivity was more higher than that of high performance liquid chromatography-electrochemical detector. Urinary ${\alpha}$-naphthylamine was detected in only one worker among nine workers. The level of ${\alpha}$-naphthylamine in urine was 6.42 ng/ml.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.3
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• pp.477-486
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• 2008

Acrylic resin is widely used in dental practice. However, the residual monomer in acrylic resin could act as a negative biocompatability on human body. The aim of this study was to evaluate the amount of the monomer elution from polymerized orthodontic acrylic resin. Orthodontic acrylic resin was used in the study. The curing condition of the resin was controlled by temperature, pressure, aquatic and atmospheric environment. The duration and amount of monomer elution and timedependent plot was recorded by high performance liquid chromatography. The result showed that the only monomer eluted from the resin was methyl methacrylic acid. And the amount of the monomer elution has diminished considerably by time progress especially within 24 hours. Furthermore, elution of the residual monomer was significantly lower in group of pressure, moisture and elevated temperature than control (p<.05). According to this study, it was thought that the elution of residual monomer might be influenced by curing environment.

• Journal of the Korean Chemical Society
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• v.28 no.1
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• pp.54-61
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• 1984

The species and equilibrium of molybdate and tungstate have been investigated from the elution behaviors of those in various concentrations of nitric acid and the UV spectra obtained at the various Z values. In higher concentrations than 0.05M nitric acid, the nitarte complex species of $MoO_2(NO_3)_2$ seems to form from the $MoO_2^{2+}$ ions formed by the following equation: $Mo_8O_{26}^{4-} + 20H^+$ ${\rightleftharpoons}$ $8MoO_2^{2+}$ + $10H_2O$. In the case of tungstate, the elution behaviors of tungstate in nitric acid medium are similar to those of perchloric acid, so we think the equilibrium of tungstate existed in perchloric acid could be also existed in nitric acid. These elution behaviors of tungstate are compared with the UV spectra obtained at the various Z values.

• Korean Journal of Food Science and Technology
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• v.25 no.6
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• pp.698-702
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• 1993

Effect of heating temperature on elution patterns of soluble carbohydrate of legume starches and the texture of starch gels was investigated. The elution profiles of soluble carbohydrate obtained by Sepharose 2B-CL showed that the larger molecules were leached as the heating temperature increased. The elution profiles of soluble carbohydrate of cow pea and mung bean starches were similar, but those of kidney bean starch were different. The gel structures of cow pea and mung bean were stable with showing high values in hardness and cohesiveness. But red bean and kidney bean gels were weak in hardness and cohesiveness. As the heating temperature rised, hardness and cohesiveness were increased in gels prepared by heating for 15 min. However, the gels made by heating for 1 hour showed that less hard and more cohesive gels from cow pea and mung bean, while harder and more cohesive gels from red bean and kidney bean were obtained as the heating temperature increased from $85^{\circ}C\;to\;95^{\circ}C$.