• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.192-198
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• 2023

In this study, the components of microwave-assisted extracts obtained from Thuja orientalis leaves were analyzed, and the cytotoxicity, antibacterial and antiviral activities were evaluated. The predominant components from microwave-assisted extraction were catechin, leucopelargonidin, arecatannin, quinolone, and kaempferol derivatives, which are classified in the flavonoid and tannin groups. We observed that the 0.11 mg/mL of extract concentration did not show cytotoxicity in HaCaT cells. The antibacterial activities were tested according to the guidelines of methods for determining the bactericidal activity of antimicrobial agents. The extracts showed 99.9% antibacterial efficiency against gram-positive S. aureus, while the antibacterial effect on gram-negative E. coli was insignificant. When the extract concentration and contact time with bacteria were increased, 99.9% antibacterial efficiency was observed for E. coli as well as S. aureus. Following the standard to assess the activity of microbicides against viruses in suspension (ASTM-E1052-20), the antiviral efficiency was more than 99.99% for influenza A (H1N1) and SARS-CoV-2. These results suggest its potential use in antiviral disinfectants, surface coatings, personal protective equipment, and textiles.

• Journal of Food Hygiene and Safety
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• v.33 no.2
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• pp.118-123
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• 2018

The objective of this study was to develop a sensitive method for the identification and determination of nitrovin in fishery products by using a solid-phase extraction (SPE), as performed with a liquid chromatography-tandem mass spectrometry (LC-MS/MS). The samples were extracted with a mixture of acetonitrile and water, and were then defatted with acetonitrile saturated hexane, after which further clean-up was accomplished with SPE on the hydrophilic-lipophilic balance (HLB) cartridges. The analytes were subsequently ionized in the positive mode of an electrospray ionization (ESI), and where thereby detected in a process of multiple reaction monitoring (MRM). The linearity (expressed as correlation coefficients) of the matrix calibration curves was > 0.985. The limit of the quantification for the nitrovin was measured at 0.001 mg/kg. The accuracy (expressed as average recovery) was noted between 72.1 and 122%. The precision (expressed as coefficient variation) was noted from 2.9 to 16.9%. According to the CODEX CAC/GL-71 guideline accuracy, precision, linearity, and limit of detection were determined in three matrices (which were flatfish, eel and shrimp). The proposed method was suitable for analyzing the associated nitrovin residues. This application and result can also be a factor to contribute to the non-detection drugs management in fishery products.

• Analytical Science and Technology
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• v.28 no.2
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• pp.125-131
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• 2015

A method was developed and fully validated for the determination of terbutaline, a β₂-receptor agonist, in human plasma. Plasma samples were prepared by solid-phase extraction with Sep-Pak silica, followed by high-performance liquid chromatography (HPLC). The terbutaline was pre-separated from the interfering components in plasma on a Luna C18 (2) column, and terbutaline and salbutamol as an internal standard were resolved and determined on a Luna Silica column. The two columns were connected by a switching valve equipped with silica pre-column. The pre-column was used to concentrate the terbutaline in the eluent from the C18 column before back-flushing onto the silica column with fluorescence detection at an excitation/emission wavelength of 276/306 nm. The method was shown to be specific by testing six different human plasma sources. Linearity was established for a concentration range of 0.4-20.0 ng/mL with a correlation coefficient of 0.9999. The lower limit of quantitation was 0.4 ng/mL with a precision of 10.1% as C.V.%.

• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.1000-1005
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• 1997

The properties of ceramics by solid-state reaction with hydroxyapatite[$Ca_{10}(PO_4)_6(OH)_2$], which was isolated from tuna bone by wet milling process were investigated. The bulk density $2.93g/cm^3$ at $1350^{\circ}C$ was close to the calculated density $3.21g/cm^3$. On X-ray measurements, the major phases were identified as hydroxyapatite at below $1300^{\circ}C$, but the whitlockite [$Ca_3(PO_4)_2$] phases were appeared due to a decomposition of hydroxyapatite with temperature. The microstructures of sintering specimens were shown as small closed pores between grain boundaries. The mean bending strength of the sintered hydroxyapatite by solid-state reaction is about 58 MPa and this value is higher than that of the articular cartilage maximum strength, 40MPa.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.5
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• pp.293-302
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• 2015

Halonitromethanes (HNMs) are one of the most toxic groups of disinfection by-products. Recently, various studies have been fulfilled. An automated headspace-solid phase microextraction (SPME) gas chromatography/electron capture detector (GC-ECD) technique was developed for routine analysis of 9 HNMs in water samples. The optimization of the method is discussed. The limits of detection (LOD) and limits of quantification (LOQ) range from 90 ng/L to 260 ng/L and from 270 ng/L to 840 ng/L for 9 HNMs, respectively. Matrix effects in tap water and sea water were investigated and it was shown that the method is suitable for the analysis of trace levels of HNMs, in a wide range of waters. The method developed in the present study has the advantage of being rapid, simple and sensitive.

• The Korean Journal of Pesticide Science
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• v.19 no.4
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• pp.370-393
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• 2015

This study was conducted to compare STQ method, multi-residue method in Korean food code and QuEChERS method for validated selected and accuracy, reproducibility and efficiency. A total of 45 selected and targeted pesticides were the analyzed by GC and 5 of them were crops (apple, potato, green pepper, rice, soy bean). $R^2$ values were calculated in the standard calibration curve was over 0.990. Recovery tests were performed by three replications in two levels and the relative standard deviation of the repeated experiments was less than 30%. The average percentage of recoveries in the multi-residue method in Korean food code was 89.13%, QuEChERS method was 92.45% and STQ method was 85.28%. In addition, matrix effects in multi-residue method in Korean food code was 24.61%, QuEChERS method was 23.98% and STQ method showed 11.24%. The STQ method is easy and showed high clean-up effect in extracting the sample solution than the QuEChERS method and clean-up with C18, PLS, PSA cartridge columns. A large volume of the sample was injected in order to compensable for the problem, that occurred due to high detection limit in the analyser. When the STQ method was applied using a large volume injector, the standard calibration curve showed a higher linearity $R^2=0.990$, and method detection limit was 0.01 mg/kg. It showed an average recovery of 91.84% and the relative standard deviations of three replications repeated in two level process was less than 30% and had an average matrix effect of 17.90%.

• Analytical Science and Technology
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• v.25 no.6
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• pp.460-466
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• 2012

An environmentally friendly, so-called green, high performance liquid chromatography method was developed and validated for the determination of trans, trans-muconic acid (t,t-MA) in human urine as a biomarker of benzene exposure. After urinary t,t-MA was extracted and enriched using solid-phase extraction, a MF-Ph1 SG80 ($150mm{\times}2.0mm$ I.D., 5 ${\mu}m$) column with a mobile phase of 10 mM $KH_2PO_4$ containing 0.1% $H_3PO_4$ was used for isocratic separation of t,t-MA with UV detection at 259 nm. The calibration curve was constructed in the range of 0.1-5.0 mg/L with good linearity ($r^2$=0.9992). The intra-day and inter-day precision (as RSD) were 0.9-8.5% and 3.1-4.5%, respectively. The average recovery ranged from 97.5% to 101.7%. The green sample preparation and separation with no organic solvents were successfully achieved. The validated method would be suitable for the routine biological monitoring of benzene exposure in the occupational settings.

• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.994-999
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• 1997

The sintering properties of hydroxyapatite isolated from tuna bone and hydroxyapatite-containing wollastonite sintered by solid-state reaction was investigated. As the sinterability of hydroxyapatite dependent upon the particle size by dry milling, it showed a sintering. But the hydroxyapatite-containing wollastonite was appeared good sinterability. On X-ray measurements, the major phases of hydroxyapatite-containing wollastonite by solid state reaction at $1250^{\circ}C$ were identified as hydroxyapatite and pseudowollastonite(${\alpha}-CaSiO_3$). And the phases appeared as whitlockite [$Ca_3(PO_4)_2$] by decomposition of hydroxyapatite at higher temperature above $1250^{\circ}C$. The shapes of microstructure on SEM images changed from porous to dense bulk by elevating temperature. The mean bending strength of hydroxyapatite-containing wollastonite sintered by solid-state reaction at $1300^{\circ}C$ was about 18 MPa, it was close to the cancellous bone's maximum strength, 20 MPa.

• Applied Chemistry for Engineering
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• v.16 no.3
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• pp.323-327
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• 2005

Pentachlorophenol (PCP) is a representative compound of chlorophenol derivatives which are especially toxic and potentially carcinogenic compounds in the priority pollutant list of the EPA (Environmental Protection Agency, USA). The aim of this study was to investigate an analysis method of PCP in infinitesimal quantity retained in paper. PCP in paper was pretreated by solid phase extraction (SPE) in a phenyl cartridge. The extracted sample was acetylated or silylated and analyzed with GC/MS-SIM. The detection sensitivity of silylated PCP was improved significantly when compared with those of PCP itself and acetylated PCP. As a test specimen, an office paper and a wallpaper were used.

• 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.