• Membrane Journal
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• v.9 no.4
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• pp.230-239
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• 1999

Perchlorate ion-selective electrodes in PVC membranes that respond linearly to concentration 106 M were developed by incorporating the quaternary phosphonium salts as a canier. The effects of the chemical structure, the contents of canier, the kind of plasticizer and the membrane thickness on electrode characteristics such as the electrode slope, the linear respone range and the detection limit were studied. With this results, the detectable pH range, selectivity coefficients and AC impedance characteristics were compared and investigated. The perchlorate ion substituents of the quaternary phosphonium salts like tetraoctylphosphonium perchlorate (TOPP) , tetraphenylphosphonium perchlorate(TPPP), and tetrabutylphosphonium perchlorate(TBPP) as a canier were used. The electrode characteristics were better in the ascending order of TBPP < TPPP < TOPP, with the increase of carbon chain length of the alkyl group. Dioctylsebacate(OOS) was best as a plasticizer, the canier contents were better with 11.76 wt% and the optimum membrane thickness was 0.19 mm. Under the above condition, the electrode slope was 56.58 mV/$^P{ClO}_4$,the linear response range was $10^{-1}$\times$10^{-6}$ M, the detection limit was 9.66 x $10^{-7}$ M. The performance of electrode was better than Orion electrode. The electrode potential was stable within the pH range from 3 to 11. The order of the selectivity coefficients for the perchlorate ion was sol < F < Br < 1. With the result of impedance spectrum, it was found that the equivalent circuit for the electrode could be expressed by a series combination of solution resistance, parallel circuit consisting of the double layer capacitance and bulk resistance and Warburg impedance. And solution resistance was almost not appeared and Warburg impedance was highly appeared by diffusion. Then Warburg coefficient was 1.32$\times$$10^74 $\Omega$ $\cdot$ ${cm}^2/s^{1/2}$.

• Analytical Science and Technology
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• v.24 no.4
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• pp.243-248
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• 2011

A selective determination method of mercury (II) ion in aqueous solution by luminol-based chemiluminescence system (luminol CL system) has been developed. Determination of metal ions such as copper (II), iron (III), chromium (III) ion in solution by the luminol CL system using its catalytic role in the reaction of luminol and hydrogen peroxide has been reported by several groups. In this study, the catalytic activity of mercury (II) ion in the reaction of luminol and hydrogen peroxide was observed by the enhanced CL intensity of the luminol CL system. Based on this phenomenon, experimental conditions of the luminol CL system were investigated and optimized to determine mercury (II) ion in aqueous solution. While mercury (II) ion in mixed sample solution containing mercury (I) and (II) ions highly enhanced the CL intensity of the luminol CL system, the mercury (I) ion could not enhanced the CL intensity. Thus selective determination of the mercury (II) ions in a mixture containing mercury (I) and (II) ions could be achieved. Each concentration of mercury (I) and (II) ions in aqueous solution can be obtained from the results of the CL method that give the concentration of only mercury (II) ion and the inductively coupled plasma (ICP) method that give the total concentration of mercury ions. On the optimized conditions, the calibration curve of mercury (II) ion was linear over the range from $1.25{\times}10^{-5}$ to $2.50{\times}10^{-3}M$ with correlation coefficient of 0.991. The detection limit of mercury (II) ion in aqueous solution was calculated to be $1.25{\times}10^{-7}M$.

• Korean Journal of Food Science and Technology
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• v.43 no.2
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• pp.161-168
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• 2011

The purpose of this study was to evaluate microbiological contamination of fresh vegetables in Korea. Twenty types of vegetables were tested for total aerobic bacteria, coliforms, Escherichia coli, yeast and mold, and pathogenic bacteria such as Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, Salmonella, E. coli O157:H7, Cronobacter sakazakii, Shigella, and Campylobacter. Levels of total aerobic bacteria and coliform on 20 vegetables were between 3.74 and 8.04 log CFU/g, and 0.16 and 5.02 log CFU/g, respectively. The highest contamination levels of total aerobic bacteria were observed on water dropwort, sprouts, mungbean sprout, and ballflower root. There was no significant difference (p>0.05) in microbial contamination levels of total aerobic count, coliform, E. coli, yeast and mold between organic and nonorganic vegetables. When isolation methods using selective agars were applied, L. monocytogenes, B. cereus, Salmonella and Campylobacter were isolated from some fresh vegetable samples. Results of API kit tests showed that L. monocytogenes was identified on Chinese cabbage, cucumber, soybean sprouts, and iceberg lettuce while Salmonella was identified on Korean leek. Furthermore, Campylobacter jejuni was also identified in more than 50 of the 100 samples. However, when positive samples from API kit were tested for real-time PCR or 16S rRNA sequencing method, only B. cereus from perilla leaf, carrot, water dropwort, and sprouts showed positive results. These results indicate that selective agar and API kit detection methods might result in false positive results for some pathogens. Therefore, studies need to improve isolation or confirmation methods for such pathogens.

• Journal of the Korean Chemical Society
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• v.55 no.3
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• pp.478-485
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• 2011

Merocyanine derivatives transformed from spiropyran-containing compounds by irradiating the light of ultraviolet (UV) include zwitterion of phenolate anion and amine cation. Complexation of this phenolate anion on merocyaninemodified surface and Ni ion among metal ions led to a change of surface charge and it was measured with kelvin prove force microscopy (KFM). We found that the resultant surface potential decreased linearly as UV-exposed time increased, and finally were saturated. Also it was analyzed through XPS the immobilized amount of Ni ions was increased according to increase of UV-exposed time. It is considered that these properties could be applied for detection and a quantitative control of different metal ions. Further research is to aim construct specific scaffold/matrix which enable high selective, high sensitive and, especially, a quantitative immobilization of metal ions-binding biomaterials such as proteins and cells.

• Analytical Science and Technology
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• v.12 no.5
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• pp.408-414
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• 1999

A selective and sensitive method for the derivatization of total homocysteine (Hcy) and the related compounds in plasma by gas chromatograph (GC)-electron capture detector (ECD) has been developed. To determine total homocysteine, cysteine (Cys), and methionine (Met) in human plasma using GC-ECD, analytes were reduced and converted into their N(O,S)-ethylearbonyl pentafluoropropyl (PFP) ester by derivatization with ethyl chloroformate and pentafluoropropyl alcohol (PFP-OH) in plasma. The best derivatizing agent N(O,S)-ethyl carbonyl PFP ester, was chosen by comparing the sensitivity of derivatized analysis in GC-ECD. The derivatized analytes in plasma were extracted by chloroform, and subsequently back-extracted with hexane and analyzed by GC-ECD. The calibration carves ($R^2$ > 0.990) were linear over the range $5-50{\mu}mol/L$ of Hcy and Met, $40-400{\mu}mol/L$ of Cys spiked in plasma. The detection limit observed by the established method was below $0.5{\mu}mol/L$. This method is highly sensitive and specific in the analysis of Hcy, Cys, and Met. Therefore, we suggest that this method is appropriate in the analysis of trace concentration of Hcy, Cys, and Met in biological fluids.

• Journal of Food Hygiene and Safety
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• v.34 no.6
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• pp.519-525
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• 2019

The Ministry of Food and Drug Safety (MFDS) is amending its test methods for health functional foods (dietary food supplements) to establish regulatory standards and specifications in Korea. In this regard, we are continuing our research on analytical method development for the items listed in the Korean Health Functional Food Codex. In this study, we have developed a sensitive and selective test method that could simultaneously separate and determine coenzyme Q10 based on liquid chromatographic-tandem mass spectrometry (LC-MS/MS). Calibration curves showed linearity with a correlation coefficient (R²) of > 0.999 and the limits of detection (LODs) and limits of quantitation (LOQs) were in the range of 26.0 ㎍/L and 78.9 ㎍/L, respectively. The recovery results ranged between 98.6-107.0% at 3 different concentration levels with relative standard deviations (RSDs) less than 5%. The proposed analytical method was characterized with high resolution of the coenzyme Q10 and the assay was fully validated as well.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.5 no.2
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• pp.89-100
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• 2019

In our previous studies, we developed a ¹⁸F-labeled TSPO-binding ligand, named [¹⁸F]CB251, which has been proved to be a promising TSPO-binding PET radiotracer for the detection and monitoring of TSPO expression in pathological diseases. (Ki = 0.27 nM for TSPO, 1.96% ID/g of tumor uptake at 1h post-injection) Based on these results, we utilized 6,8-dichloro-2-phenylimidazo[1,2-a]pyridineacetamide analogs, CB185 (1) as a targeting moiety for the selective delivery of probes and anticancer molecules to TSPO-overexpressed tissues. In this study, we designed CB185 derivatives contains different PEG chains (n = 1, 3 and 5) and fluorescence dye (Cy5) to identify the necessary space between a TSPO-binding ligand and an anticancer agent. Three CB185 derivatives (11a-c) which contains Cy5 and PEG chain, were synthesized and the effect of PEG additive on their TSPO-binding affinities were evaluated using in vitro assays. The binding affinity for compounds 11a-c was lower than that of PK11195 (Ki = 3.2 nM), but still characterized by nanomolar binding affinity for TSPO (Ki = 46.5 nM for 11a, 51.0 nM for 11b, and 388.5 nM for 11c). These results showed that the conjugates are characterized by a moderate binding affinity toward TSPO except for compound 11c, which PEG chain consist of five PEG monomers. Our finding might add useful information to decide the appropriate PET chain length for developing new TSPO-targeting drug carriers.

• Journal of Preventive Medicine and Public Health
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• v.21 no.1 s.23
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• pp.89-98
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• 1988

While there have been not a few reports on the seroepidemiological characteristics of hepatitis B virus (HBV) infection in Korea, most of them, however, have had several limitations; operational definition of HBV infection, validity of detection methods of HBV serologic markers, size of the study population, and confirmation of the vaccination history against HBV, etc. In order to avoid such limitations, authors randomly selected 1,495 healthy adults among the 217,511 insured (target population) of Korean Medical Insurance Corporation, living in seoul, and tested HBV serologic markers by RIA method and conducted direct interview to them. Although HBV serologic markers (HBsAg, anti-HBs and anti-HBc) of all the subjects were tested, 392(26.2%) of interview failure cases and 361 vaccinee were excluded from the actual population. Finally, the serologic markers tested of 742 nonvaccinee (study population) only were analysed for the seroepidemiologic observation of the natural infection of HBV. The seroepidemiological characteristics of HBV infection in Korea were as follows ; 1. Point prevalence of HBs antigenemia was 11.7(9.1{\sim}14.3)% in male, which was slightly higher than that of female, 9.5($3.7{\sim}15.3$)%. This level was one of the highest among those of Asian-Pacific countries. Decreasing tendency of HBsAg prevalence alter the age of 50 was observed, which seems to be due to selective attrition of HBV chronic carriers among the healthy adults and/or to the limited-lasting duration of the HBs antigenemia, in part. 2. Point prevalence of anti-HBc(78.8% in male,50.9% in female) was higher than that of anti-HBs(65.2% in male,46.6% in female), respectively. And both of them were higher in male than in female. Increasing tendency of the prevalence of both antibodies was observed by age, which seems to be largely due to recurrent infection in adults and to some cumulative effect, in part, of their relatively longer-lasting duration. 3. The level of HBV infection defined by positive for at least one of the 3 serologic markers of HBV by RIA method was 84.7($81.8{\sim}87.6$)% in male and 61.2($51.9{\sim}70.5$)% in female, which was also one of the highest among those of Asian-Pacific countries. The proportion of susceptible population to HBV infection among healthy adults was 15.3% in male and 38.8% in female. 4. The relative frequency of current or past infection and chronic carrier among HBV infected person was estimated. The currently or past infected was estimated 75.7% in male and 71.8% in female, and chronic carrier state, 13.8% in male and 14.1% in female. The analysis of the geometric mean of the antibody titer in anti-HBs positive sera indicated also to be compatible with the above findings, suggesting that active, even though inapparent, infection of HBV occur so frequently among healthy adults in Korea.

• Korean Journal of Veterinary Research
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• v.41 no.3
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• pp.421-427
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• 2001

This study was performed to evaluate the embolized kidney and contralateral normal kidney using computed tomography (CT) and enhanced computed tomography. Experimental hydronephrosis was induced by ligation of unilateral ureter in Beagle dogs. Renal artery embolization was performed using selective catheterization in the hydronephrotic kidney of seven dogs and EKG, $SpO_2$, body temperature, pulse, and repiratory rate were within normal ranges during procedures. Iohexol-ethanol solution was used as embolic material. There were no dogs expired after TAE-Ra and no side effects associated with regurgitation of iohexol-ehtanol solution. Revascularization of renal artery was not found in angiography in dogs treated by TAE-RA at immediately after TAE-RA and 14 days after TAE-RA. CT showed dilation of urinary collection system and ventral displacement of spleen at 14 days after TAE-RA in one dog not treated by TAE-RA and experimental group treated by TAE-Ra. CT two month after TAE-RA showed the shrunken embolized kidney in experimental group. Transverse CT with contrast enhancement demonstrated the increase of signal intensity at thinned renal cortex in control group not treated by TAE-Ra at 30 days and 60 days, however, there was no increase of signal intensity at shrunken embolized kidney at 60 days after TAE-RA. CT was useful modality for evaluation of the morphology and the size of embolized kidney and contralateral normal kidney. Enhanced CT was availabel for the detection of revascularization of renal artery after TAE-RA in dogs with hydronephrosis. It is conclued that CT is useful modality for the monitoring of the revascularization of the renal artery after TAE-RA.

• Journal of Food Hygiene and Safety
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• v.31 no.6
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• pp.465-470
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• 2016

Sample preparation methods were evaluated for effectiveness in detecting foodborne pathogens from sprout seeds. The methods included: Rinse.-Test portions were rinsed with 0.1% peptone water, and the pellet after centrifugation was inoculated into pre-enrichment media; and Sprouting.-Seed samples were sprouted before pre-enrichment and sprouted seeds were inoculated into pre-enrichment media. In rinse method, E. coli was isolated from 13 of 280 sample units. In sprouting method, E. coli was isolated from 12 of 135 sample units. E. coli O157:H7, Salmonella spp., and L. monocytogenes were not detected in any of the samples. In the trials for recovering Salmonella enterica from artificially contaminated alfalfa seeds, the soak, rinse, and sprouting methods were evaluated. The detection rates of S. enterica were statistically different according to the amount of the sample tested and selective medium type (P < 0.05).