• Analytical Science and Technology
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• v.21 no.4
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• pp.272-278
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• 2008

Methods to separate 14 rare earth elements (REEs) and yttrium by the $AG^{(R)}$ 50W-X8 cation exchange resin, and to determine REEs by inductively coupled plasma atomic emission spectrophotometry (ICP-AES) were described. Ion exchange capacities of REEs on the resin were so high that the REEs were quantitatively ion exchanged under the flow rate of 0.3~1.0 mL/min at pH 1~6. The breakthrough capacity curve of the REEs showed that ion exchange capacities of light REEs (Cerium group) were greater than that of the heavy REEs (Yttrium group). When $200{\mu}g$ of each REEs was ion exchanged on 100 mg of resin, most of the heavy REEs were quantitatively desorbed with 10 mL of 2.0 M of $HNO_3$, while most of the light REEs with 30 mL. The method was applied to the monazite sample. The REEs could be separated from matrix, since ion exchange capacities of matrix ions of Ca, Ti, Mg, Mn were much lower than that of the REEs. However the relative standard deviations of the analytical results by the present method were not improved, as high as 1~5%.

• Journal of the Korean Society of Food Culture
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• v.22 no.2
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• pp.246-253
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• 2007

Mineral and volatile flavor compounds of Pimpinella brochycarpa N., a perennial Korean medicinal plant of the Umbelliferae family, were analyzed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and simultaneous steam distillation extract (SDE)-gas chromatography mass spectrometry (GC/MS), head space solid phase micro-extraction (HS-SPME)-GC/MS. Mineral contents of the stalks and leaves were compared and the flavor patterns of the fresh and the shady air-dried samples were obtained by the electronic nose (EN) with 6 metal oxide sensors. Principal component analysis (PCA) was carried out using the data obtained from EN. The 1st principal values of the fresh samples have + values and the shady air-dried have - values. The essential oil extracted from the fresh and the shady air-dried by SDE method contain 58 and 31 flavor compounds. When HS-SPME method with CAR/PDMS fiber and PDMS fiber were used, 34 and 21 flavor compounds. The principal volatile components of Pimpinella brachycarpa N. were ${\alpha}$-selinene, germacrene D, and myrcene.

• Journal of Food Hygiene and Safety
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• v.38 no.3
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• pp.158-163
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• 2023

This study aimed to determine mercury (Hg), methylmercury (MeHg), and selenium (Se) levels in deep-sea fishes distributed in Gyeonggi-do, South Korea. Concentrations of Hg, MeHg, and Se were measured by using a mercury analyzer and Inductively Coupled Plasma - Mass Spectrometry (ICP-MS). The average content (mg/kg) in the seafood samples was as follows: Hg, 0.7647 (0.0182-5.3620), MeHg, 0.0764 (0.0096-0.8750), and Se, 0.4728 (0.1075-3.5100). All the levels of MeHg were below the recommended standards of the Ministry of Food and Drug Safety i.e., <1.0 mg/kg. Recent studies have shown that Se prevents Hg toxicity. The average daily intake in humans was 3.3 ㎍/kg, which was lower than the recommended amount (50-200 ㎍/person/day). The weekly intake of Hg and MeHg was calculated to be 6.07% and 1.90%, respectively, of the provisional tolerable weekly intake (PTWI). This study showed that the weekly intake of Hg and MeHg from abyssal fish was less than the PTWI recommended by the Joint FAO/WHO expert committee on food additives. Therefore, the levels reported in this study are presumed to be adequately safe.

• Journal of the korean academy of Pediatric Dentistry
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• v.51 no.2
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• pp.149-164
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• 2024

This study compared the solubility, water absorption, dimensional stability, release of various ions (hydroxyl, calcium, sulfur, strontium, and silicon), and cytotoxicity of light-cured resin-modified pulp-capping materials. Resin-modified calcium hydroxide (Ultra-blend^TM plus, UBP), light-cured resin-modified calcium silicate (TheraCal LC^TM, TLC), and dual-cure resin-modified calcium silicate (TheraCal PT^TM, TPT) were used. Each material was polymerized; solubility, 24-hour water absorption, and 30- day dimensional stability experiments were conducted to test its physical properties. Solubility was assessed according to the ISO 6876 standard, and 24 hours of water absorption, 30 days of dimensional stability were assessed by referring to the previous protocol respectively. Eluates at 3 and 24 hours and on 7, 14, and 28 days were analyzed according to the ISO 10993-12 standard. And the pH, Ion-releasing ability, cell proliferation rate, and cell viability were assessed using the eluates to evaluate biochemical characteristics. pH was measured with a pH meter and Ion-releasing ability was assessed using inductively coupled plasma atomic emission spectrometry (ICP-AES). Cell proliferation rate and cell viability were assessed using human dental pulp cells (hDPCs). The former was assessed by an absorbance assay using the CCK-8 solution, and the latter was assessed by Live and Dead staining. TPT exhibited lower solubility and water absorption than TLC. UBP and TPT demonstrated higher stability than TLC. The release of sulfur, strontium, calcium, and hydroxyl ions was higher for TLC and TPT than for UBP. The 28-day release of hydroxyl and silicon ions was similar for TLC and TPT. TLC alone exhibited a lower cell proliferation rate compared to the control group at a dilution ratio of 1 : 2 in cell proliferation and dead cells from Live and Dead assay evaluation. Thus, when using light-cure resin-modified pulp-capping materials, calcium silicate-based materials can be considered alternatives to calcium hydroxide-based materials. Moreover, when comparing physical and biochemical properties, TPT could be prioritized over TLC as the first choice.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.590-598
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• 2005

An adequate method to identify chromium separation, Cr(III) and Cr(VI), in water samples were studied by using High Performance Liquid Chromatography(HPLC) coupled with Inductively Coupled Plasma Mass Spectometer(ICP-MS) equipped with Dynamic Reaction Cell(DRC). The characteristic distribution of Cr(III) and Cr(VI) in the raw water taken at the six water intake stations in Seoul, was analyzed by the method developed by the authors. The chromium species separated by HPLC was isocratically conducted by using tetrabutylammonium phosphate monobasic(1.0 mM TBAP), ethylenediaminetetraacetic acid(0.6 mM EDTA) and 2% v/v methanol as the mobile phase. 5% v/v methanol was used as flushing solvent. A reactive ammonia($NH_3$) gas was used to eliminate the potential interference of $ArC^+$. Several Parameters such as solvent ratio, pH, flow rate and sample injection volume were optimized for the successful separation and reproducibility. Although it has been reported thai the separation sensitivity of Cr(III) is superior to that of Cr(VI), the authors observed Cr(VI) was more sensitive than Cr(III) when ammonia($NH_3$) gas was used as the reaction gas. It took less than 3 minutes to analyze chromium species with this method and the estimated detection limits were $0.061\;{\mu}g/L$ for Cr(III) and $0.052\;{\mu}g/L$, for Cr(VI). According to the results from the analysis on chromium species in the raw water of the six intake stations, the concentrations of Cr(III) ranged from 0.048 to $0.064\;{\mu}g/L$(ave. $0.054\;{\mu}g/L$) while that of Cr(VI) ranged from 0.014 to $0.023\;{\mu}g/L$(ave. $0.019\;{\mu}g/L$). Recovery ratio was very high($90.1{\sim}94.1%$). There were two or three times more Cr(III) than Cr(VI) in the raw water.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.7
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• pp.1038-1048
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• 2010

The purpose of this study was to investigate some heavy metals (Pb, Cd, Cr, Cu, Hg) in 52 commercial herbal pills used as general processed food, to identify weekly heavy metal intakes from herbal pills and to evaluate their potential health risks. The samples were digested with a microwave and determinations of heavy metal residues were carried out by inductively coupled plasma mass spectrometry (ICP-MS) and mercury analyzer. The mean values of heavy metal contents for herbal pills used as general processed food were Pb 0.421 (0.032~1.630), Cd 0.157 (0.011~0.515), Cr 1.033 (0.112~9.933), Cu 6.923 (1.333~16.755), Hg 0.010 (0.001~0.088) mg/kg. Lead contents of herba and cadmium of algae, herba were high (ANOVA-test, p<0.05). Levels of cadmium concentrations exceeding WHO reference values (0.3 mg/kg) were observed in 10 samples (4 species). The significant correlation was observed between Pb and Cd (r=0.633, p<0.01). The weekly intakes of Pb, Cd, Cr, Cu, Hg from herbal pills were 1.112 (0.072~5.088), 1.614 (0.029~9.257), 3.000 (0.252~23.690), 0.182 (0.008~1.235), 0.220 (0.000~0.420)%, respectively, as compared with the Provisional Tolerable Weekly Intake (PTWI) established by Joint FAO/WHO Expert Committee for food safety evaluation. Our data suggest regulations limiting heavy metals in herbal pills used as general processed food.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.80-81
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• 2012

Recently, one of the critical issues in the etching processes of the nanoscale devices is to achieve ultra-high aspect ratio contact (UHARC) profile without anomalous behaviors such as sidewall bowing, and twisting profile. To achieve this goal, the fluorocarbon plasmas with major advantage of the sidewall passivation have been used commonly with numerous additives to obtain the ideal etch profiles. However, they still suffer from formidable challenges such as tight limits of sidewall bowing and controlling the randomly distorted features in nanoscale etching profile. Furthermore, the absence of the available plasma simulation tools has made it difficult to develop revolutionary technologies to overcome these process limitations, including novel plasma chemistries, and plasma sources. As an effort to address these issues, we performed a fluorocarbon surface kinetic modeling based on the experimental plasma diagnostic data for silicon dioxide etching process under inductively coupled C4F6/Ar/O2 plasmas. For this work, the SiO2 etch rates were investigated with bulk plasma diagnostics tools such as Langmuir probe, cutoff probe and Quadruple Mass Spectrometer (QMS). The surface chemistries of the etched samples were measured by X-ray Photoelectron Spectrometer. To measure plasma parameters, the self-cleaned RF Langmuir probe was used for polymer deposition environment on the probe tip and double-checked by the cutoff probe which was known to be a precise plasma diagnostic tool for the electron density measurement. In addition, neutral and ion fluxes from bulk plasma were monitored with appearance methods using QMS signal. Based on these experimental data, we proposed a phenomenological, and realistic two-layer surface reaction model of SiO2 etch process under the overlying polymer passivation layer, considering material balance of deposition and etching through steady-state fluorocarbon layer. The predicted surface reaction modeling results showed good agreement with the experimental data. With the above studies of plasma surface reaction, we have developed a 3D topography simulator using the multi-layer level set algorithm and new memory saving technique, which is suitable in 3D UHARC etch simulation. Ballistic transports of neutral and ion species inside feature profile was considered by deterministic and Monte Carlo methods, respectively. In case of ultra-high aspect ratio contact hole etching, it is already well-known that the huge computational burden is required for realistic consideration of these ballistic transports. To address this issue, the related computational codes were efficiently parallelized for GPU (Graphic Processing Unit) computing, so that the total computation time could be improved more than few hundred times compared to the serial version. Finally, the 3D topography simulator was integrated with ballistic transport module and etch reaction model. Realistic etch-profile simulations with consideration of the sidewall polymer passivation layer were demonstrated.

• Clean Technology
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• v.25 no.4
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• pp.311-315
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• 2019

The cation extraction and impurity separation were studied in order to investigate the recyclability of a slag produced from the steel refinery industry. Two types of slag (Slag-A, B) were collected and characterized in this study. The initial characterization by X-ray diffraction (XRD) and X-ray fluorescence (XRF) confirmed the existence of various kinds of ions in the slag such as Ca²⁺ (30 ~ 40%), Fe³⁺ (20 ~ 30%), Si⁴⁺ (15%), Al³⁺ (10%), Mn²⁺ (7%), and Mg²⁺ (3 ~ 5%). Inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis on the extracted slag using 2 M HCl as a solvent indicated that a higher concentration of Ca²⁺ was extracted as the S/L ratio was increased. The Ca²⁺ extraction concentration were found to be 8,940 mg L^-1 (Slag-A) and 10,690 (Slag-B) mg L^-1 when the S/L ratio for Ca²⁺ extraction was 0.1. However, the extract was strongly acidic ( < pH 1) at 0.1 S/L. Also the other ions (impurities) were extracted simultaneously in addition to Ca²⁺. To increase the purity of Ca²⁺ in order to transform the slag to a high value resource, a pH-swing was conducted. The impurities tended to precipitate at higher rate as the pH was increased. Notably, the Ca²⁺ rapidly precipitated above a certain pH and at a pH of 10.5, while the selectivity of Ca²⁺ was over 99%. It is expected that the aqueous solution in which high contents of Ca²⁺ was selectively dissolved in this study would be suitable for the carbonation process for reducing CO₂ and for the production of calcium carbonate.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.25 no.3
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• pp.392-404
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• 2015

Objectives: This study measured and analyzed the concentrations of crystalline silica, elemental carbon and the contribution ratio of pollutants which influence environmental and respiratory disease around the Ansim Briquette Fuel Complex in Daegu, Korea. Methods: We analyzed the crystalline silica and elemental carbon in the air according to FTIR(Fourier Transform Infrared Spectroscopy) and NIOSH(National Institute of Occupation Safety and Health) method 5040, respectively. In addition, lead stable isotopes, and carbon and nitrogen stable isotopes were analyzed using MC-ICP/MS(Multi Collector-Inductively Coupled Plasma/Mass Spectrometer), and IRMS(Isotope Ratio Mass Spectrometer), respectively. Results: The concentration of crystalline silica in the direct exposure area around the Ansim Briquette Fuel Complex was found to be $0.0014{\pm}0.0005mg/Sm^3$, but not to exceed the exposure standards of the ACGIH(American Conference of Governmental Industrial Hygienists). In the case of the autumn, the direct exposure area was found to show a level 2.5 times higher than the reference area, and on the whole, the direct exposure area was found to have a level 1.4 times higher than the reference area. The concentration of elemental carbon in the direct exposure area and in the reference area were found to be $0.0014{\pm}0.0006mg/Sm^3$, and $0.0006{\pm}0.0003mg/Sm^3$, respectively. This study confirmed the contribution ratio of coal raw materials to residentially deposited dusts in the area within 500 meters from the Ansim Briquette Fuel Complex and the surrounding area with a stable isotope ratio of 24.0%(0.7-62.7%) on average in the case of carbon and nitrogen, and 33.9%(26.6-54.1%) on average in the case of lead stable isotopes. Conclusions: This study was able to confirm correlations with coal raw materials used by the Ansim Briquette Fuel Complex and the surrounding area. The concentration of some pollutants, crystalline silica, and elemental carbon emitted to the direct-influence area around the Ansim Briquette Fuel Complex were relatively higher than in the reference area. Therefore, we need to impose continuous and substantive reduction countermeasures in the future to prevent particulate matter and coal raw materials in the study area. It is time for the local government and authorities to prepare active administrative methods such as the relocation of Ansim Briquette Fuel Complex.

• Journal of Food Hygiene and Safety
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• v.34 no.6
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• pp.562-570
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• 2019

The heavy metal concentrations in dried seafoods commonly consumed in Gyeonggi-do were analyzed. Concentrations of lead (Pb), cadmium (Cd), mercury (Hg) and selenium (Se) were measured in 95 samples with an inductively-coupled plasma-mass spectrometer (ICP-MS) and an Hg analyzer. The average concentration [mean±SD(minimum-maximum) mg/kg] of heavy metals were as follows: Pb 0.062±0.071(0.002-0.428), Cd 0.083±0.100(0.004-0.540), Hg 0.012±0.012(N.D-0.054) and Se 0.839±0.371(0.362-2.124). All the levels were below the recommended standards of the MFDS (Ministry of Food and Drug Safety). In the comparison of heavy metal content by anchovy size, it was shown that mercury was significantly higher in large anchovy (P<0.05). Selenium levels were found to differ significantly in small anchovy and large anchovy (P<0.05). Pb, Cd and Hg were significantly higher in Tiger prawn among shrimp (P<0.05). The heavy metal and selenium levels of anchovy and shad were highest in the intestine. However, the heavy metal and selenium levels of shrimp were highest in the head. In addition, weekly (monthly) intake of mercury and cadmium from dried seafoods was found to be 0.712% and 2.978% of PTW(M)I (Provisional Tolerable Weekly(Monthly) Intake) respectively. Therefore, it was found that dried seafoods were safe for consumption.