• Analytical Science and Technology
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• v.33 no.3
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• pp.125-133
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• 2020

Methylisothiazolinone (MIT) and chloromethylisothiazolinone (CMIT) cause allergic contact dermatitis and are banned cosmetics ingredients, except in rinse-off products. However, their presence has been detected in cosmetics. We report a UPLC-tandem MS/MS screening method for their simultaneous determination in cosmetics. To facilitate extraction from various matrices, pretreatment methods were developed for each sample type. The method was optimized through a series of assessments, including specificity, LOD, LOQ, linearity, recovery, stability, precision, and accuracy. The LODs and LOQs for MIT ranged from 0.054 and 0.163 ㎍ mL^-1 whereas those for CMIT ranged from 0.040 and 0.119 ㎍ mL^-1. The linear correlation coefficients (r²) were higher than 0.999. Relative standard deviations (RSDs) for both intra- and inter-day measurements ranged from 0.3 ~ 13.6 %. Recoveries at three different concentrations were within 87.9 ~ 118.9 %. The RSD for stability measurements of spiked samples was within 7 %. These results confirm the suitability of the developed method for the simultaneous quantitation of MIT and CMIT in cosmetics. Samples of 320 color cosmetics, including eyeshadows, solid lipsticks, liquid lipsticks, and nail polishes were analyzed using the developed method, and two of them were found to contain both MIT and CMIT and one of them was found to contain only MIT. This data and the method will aid the regulation of ingredients used in cosmetics.

• Fisheries and Aquatic Sciences
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• v.23 no.3
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• pp.9.1-9.6
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• 2020

Background: Fucosterol is a compound commonly found in algae that has various biological activities. The purpose of this study was to develop a high-performance liquid chromatography (HPLC) validation method for fucosterol and to compare the fucosterol contents of 11 algal species from Ulleungdo, Korea. Method: In this study, we successfully isolated and identified fucosterol from a 70% EtOH extract of Sargassum miyabei, and subsequently conducted specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy, and precision analyses for development of an HPLC validation method. Fucosterol contents were compared using the established HPLC validation conditions. Results: We successfully isolated fucosterol from a 70% EtOH extract of S. miyabei and identified it based on spectroscopic analysis. On the basis of HPLC validation using the fucosterol isolated from S. miyabei, we confirmed specificity (8.5 min), linearity (R² = 0.9998), LOD (3.20 ㎍ mL^-1), LOQ (9.77 ㎍ mL^-1), accuracy (intra-day and inter-day variation, 90-110%), and precision (RSD, 1.07%). Fucosterol contents in the 11 assessed algal species ranged from 0.22 to 81.67 mg g^-1, with the highest content being recorded in a 70% EtOH extract of Desmarestia tabacoides (81.67 mg g^-1), followed by that of Agarum clathratum (78.70 mg g^-1). Conclusions: The results indicate that 70% EtOH extracts of D. tabacoides and A. clathratum containing fucosterol with various effects can be potential alternative sources of fucosterol.

• Korean Journal of Medicinal Crop Science
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• v.24 no.4
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• pp.271-276
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• 2016

Background: In the present study, we established an HPLC (high performance liquid chromatography)-analysis method for the determination of marker compounds as a part of the material standardization for the development of health-functional foods from Salvia plebeia R. Br. extract. Methods and Results: The quantitative determination method of hispidulin as a marker compound was optimized by HPLC analysis using a YMC hydrosphere C18 column with a gradient elution system. This method was validated using specificity, linearity, accuracy, and precision tests. It showed a high linearity in the calibration curve with a coefficient of correlation ($r^2$) of 0.999995. The method was fully validated, and was sensitive, with the limit of detection (LOD) at $0.09{\mu}g{\cdot}m{\ell}^{-1}$ and limit of quantification (LOQ) at $0.27{\mu}g{\cdot}m{\ell}^{-1}$. The relative standard deviation (RSD) values of the data from intra- and inter-day precision were 0.05 - 0.22% and 0.32 - 0.42%, respectively, and the intra- and inter-day accuracy of hispidulin were 99.5 - 102.3% and 98.8 - 101.5%, respectively. The average content of hispidulin in Salvia plebeia R. Br. extract was $3.945mg{\cdot}g^{-1}$ (0.39%). Conclusions: These results suggest that the developed HPLC method is very efficient, and that it could contribute to the quality control of Salvia plebeia R. Br. extracts as a functional ingredient in health functional foods.

• Journal of the Korean Chemical Society
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• v.41 no.9
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• pp.471-482
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• 1997

GC/MS was used to find an optimum experimental condition for the screening of organic acids in urine. Urinary organic acids were isolated through the liquid-liquid extraction method (LLE) to examine the influence of pH and the effect of including the back extraction and oximation processes respectively on the extraction. When pH was adjusted to 0.5 during the extraction without oximation process, relatively higher recovery rate and the smallest relative standard deviations (0.3-12.4%) were obtained. By removing the interference, the addition of back extraction made possible surer identification of organic acids with retention time of 15-16 minutes. Under this condition, we obtained the content distribution of urinary organic acids in healthy Korean children (n=16) by establishing the calibration curves for 51 standard organic acids.

• Journal of environmental and Sanitary engineering
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• v.21 no.1 s.59
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• pp.35-43
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• 2006

Formaldehyde is important because of their irritant and toxic properties, mutagenicity and carcinogenicity. In this study, liquid chromatography-mass spectrometry (LC-MS) is used for the analysis of formaldehyde after derivatization with 2,4-dinitrophenylhydrazine (DNPH) cartridge. Analytical parameters such as linearity, repeatability and minimum detection limit were evaluated. The linearity ($r^2$) was 0.9997 when analyte concentration ranges from 25 to $200{\mu}g/l$. The relative standard deviation (%RSD) was 1.25 % for concentration of $200{\mu}g/l$. The minimum detection limit (MDL) was 0.73 ppbv. It was shown that LC-MS method has a great potential for formaldehyde analysis. The results of formaldehyde from the survey of Ban-Woll and Shi-Hwa Industrial Complex samples, the highest level was 6.20, 3.93 ppb, respectively. The highest emission level of formaldehyde at chemical plants in the Ban-Woll' Shi-Hwa Industrial Complex was 5421.25 ppb.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.10
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• pp.67-75
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• 2013

In this paper, an analytical model is presented for the source/drain parasitic resistance of FinFET. The parasitic resistance is a important part of a total resistance in FinFET because of current flow through the narrow fin. The model incorporates the contribution of contact and spreading resistances considering three-dimensional current flow. The contact resistance is modeled taking into account the current flow and parallel connection of dividing parts. The spreading resistance is modeled by difference between wide and narrow and using integral. We show excellent agreement between our model and simulation which is conducted by Raphael, 3D numerical field solver. It is possible to improve the accuracy of compact model such as BSIM-CMG using the proposed model.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.414-418
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• 2014

BACKGROUND: Benzene, toluene, ethylbenzene and xylene (BTEX), which are volatile aromatic hydrocarbons and main constituents of gasoline, are neuro-carcinogenic organic pollutants in soil and groundwater. Korea Ministry of Environment has established the maximum permissible level of BTEX in arable soil to 1, 20, 50 and 15 mg/kg, respectively. METHODS AND RESULTS: To understand an arable soil contamination by BTEX, we collected 92 samples from the arable lands around oil reservoir, and analyzed the BTEX residue using a GC-MS with head-space sampler. A linear correlation between BTEX concentration and peak areas was detected with coefficient correlations in the range of 0.9807-0.9995. The method LOQ of BTEX was 0.002, 0.014, 0.084, and 0.038 mg/kg, respectively. Recoveries of 0.5 mg/kg BTEX were found to be 73.7-96.9%. The precision was reliable since RSD percentage (0.7-7.5%) was below 30, which was the normal percent value. Also, BTEX in all samples were detected under the LOQ. CONCLUSION: These results showed that the investigated arable soils around airport and oil reservoir in Korea were not contaminated by oils.

• Journal of the Korean Society of Tobacco Science
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• v.30 no.2
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• pp.117-124
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• 2008

A solid phase microextraction (SPME) method in combination with gas chromatography/mass spectrometric techniques was used for the extraction and quantification of 12 selected agrochemical residues in tobacco. The parameters such as the type of SPME fiber, adsorption/desorption time and the extraction temperature affecting the precision and accuracy of the SPME method were investigated and optimized. Among three types of fibers investigated, polyacrylate (PA), polydimethylsiloxane (PDMS) and polydimethylsiloxane-divinylbenzene (PDMS-DVB), PDMS fiber was selected for the extractions of the agrochemicals. The SPME device was automated and on-line coupled to a gas chromatograph with a mass spectrometer. Mass spectrometry (MS) was used and two different instruments, a quadrupole MS and triple quadrupole MS-MS mode, were compared. The performances of the two GC-MS instruments were comparable in terms of linearity (in the range of 0.01$\sim$0.5 $\mu$g/mL) and sensitivity (limits of detection were in the low ng/mL range). The triple quadrupole MS-MS instrument gave better precision than that of quadrupole MS system, but generally the relative standard deviations for replicates were acceptable for both instruments (< 15%). The LODs was fully satisfied the requirements of the CORESTA GRL. Recoveries of 12 selected agrochemicals in tobacco yielded more than 80% and reproducibility was found to be better than 10% RSD so that SPME procedure could be applied to the quantitative analysis of agrochemical residues in tobacco.

• Journal of Korean Society on Water Environment
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• v.26 no.4
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• pp.622-628
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• 2010

In this study, Solid-phase microextraction (SPME) with GC/FID was studied as a possible alternative to liquid-liquid extraction for the analysis of BTEX and MTBE. Experimental parameters affecting the SPME process (such as kind of fibers, adsorption time, desorption time, volume ratio of sample to headspace, salt addition, and magnetic stirring) were optimized. Experimental parameters such as CAR/PDMS, adsorption time of 20 min, desorption time of 5 min at $250^{\circ}C$, headspace volume of 50 mL, sodium chloride (NaCl) concentration of 25% combined with magnetic stirring were selected in optimal experimental conditions for analysis of BTEX and MTBE. The general affinity of analytes to CAR/PDMS fiber was high in the order p-Xylene>Toluene>Ethylbenzene>MTBE>Benzene. The linearity of $R^2$ for BTEX and MTBE was from 0.970 to 0.999 when analyte concentration ranges from $30{\mu}g/L$ to $500{\mu}g/L$, respectively. The relative standard deviation (% RSD) were from 2.5% to 3.2% for concentration of $100{\mu}g/L$ (n=5), respectively. Finally, the limited of detection (LOD) observed in our study for BTEX and MTBE were from $7.5{\mu}g/L$ to $15{\mu}g/L$, respectively.

• Journal of Food Hygiene and Safety
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• v.26 no.1
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• pp.12-15
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• 2011

A method based on high-performance liquid chromatography (HPLC) with ultraviolet detection has been developed to quantify coenzyme Q10 (CoQ10) in raw materials and dietary supplements. Single-laboratory validation has been performed on the method to determine linearity, selectivity, accuracy, limits of quantification (LOQ) and repeatability for CoQ10. An excellent linearity (r=0.999) was observed for CoQ10 in the concentration range $15.625{\sim}500\;{\mu}g/ml$ in dietary supplement. Observed recovery of CoQ10 was found to be between 98.33 and 99.38%. LOQ was found to be $250\;{\mu}g/ml$ Repeatability precision for CoQ10 was between 0.15 and 0.21% relative standard deviation (RSD). Further, limited studies showed that some adulterants and degraded material could be satisfactorily separated from CoQ10 and identified.