• KSBB Journal
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• v.18 no.5
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• pp.429-433
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• 2003

LAL (Limulus amebocyte lysate) test to detect and quantity endotoxin is based on gellation reaction between endotoxin and LAL from a blood extract of Limulus polyphemus. The test is labor intensive requiring dedicated personnel, takes relatively long reaction time (approximately 1 hr), requires relatively large volume of samples and reagents, and its end-point detection method is rather subjective. To solve these problems, we attempted to develop a miniaturized LOC (lab-on-a-chip) prototype using PDMS and glass. Using the 62 mm (length) ${\times}$ 18 mm (width) prototype in which 2 mm (width) ${\times}$ 44.34 mm (length) ${\times}$ 100 $\mu\textrm{m}$ (depth) microfluidic channel was provided, we compared the various detection methods of gellation, turbidometric, and chromogenic assays to find the chromogenic method to be the most suitable for small volume assay. In this assay, kinetic point method was more accurate than end point method. We also found the PDMS chip thickness should be minimized to around 2 mm to allow sufficient light transmittance, which necessitated a glass slide bonding for chip rigidity. Through the miniaturization, the test time was reduced from 1 hr to less than 10 minutes, and the sample volume could be reduced from 100 ${\mu}\ell$ to 4.4 ${\mu}\ell$. In sum, this study revealed that the mini LOC could be an alternative for a semi-automated and reliable method for LAL test.

• Applied Chemistry for Engineering
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• v.31 no.6
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• pp.585-590
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• 2020

Successful early diagnosis of cancer diseases such as lung, prostate, liver and adrenocortical carcinoma is a key step in determining the cost of treatment, survival rate, and cure rate. Most of current cancer diagnosis systems including biopsy, computed tomography (CT), positron emission tomography (PET)-CT, magnetic resonance imaging (MRI), ultrasonography, etc., require expensive and complicated equipment with highly trained human resources. Global medical and scientific communities have thus made numerous efforts on developing effective but rapid disease management system via introducing a wide spectrum of point-of-care medical diagnosis devices. Among them, a lateral flow immunoassay strip technique has gained a great attention due to many advantages such as cost-effectiveness, short inspection time, and user friendly accessibility. In this mini-review, we will highlight recent research trend on the development of colorimetry based LFIA strips for cancer diagnosis and discuss the future research direction and potential applications.

• Korean Journal of Food Science and Technology
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• v.25 no.4
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• pp.299-306
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• 1993

Determination of dietary fiber contents in some Korean foods was attempted by Englyst's gas chromatographic and colorimetric methods which measure the nonstarch polysaccharide (NSP) contents NSP values, except seaweeds, by gas chromatography (x) and colorimetry (y) were very closely correlated (y=1.01x-0.52, r=0.997, n=9), NSP values by gas chromatography were lower than total dietary fiber (TDF) Haloes by AOAC method. By adding lignin to NSP values, relation between the two methods was improved. But, TDF values (y) by adding lignin to NSP values and TDF values (x) by AOAC method were related as y=0.68x-0.64 and F=0.903(n= 12), which was not closely related.

• Korean Journal of Food Science and Technology
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• v.13 no.1
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• pp.20-24
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• 1981

Residues of neoasozine in rice grain were determined by neutron activation and colorimetric techniques. Twice application of the chemical before flowering did not lead to any increased residue level while 4-times application resulted in significant increase in the residue level up to 0.54-0.75 mg $As_2O_3/kg$. The partition ratio of arsenic residues into polished rice grain and bran was 73 : 27 in 100% polishing while most of the residues in the bran was transferred to oil cake fraction during solvent extraction, reaching up to 2.9 mg $As_2O_3/kg$. The neutron activation technique was advantageous because of its high sensitivity and the smaller sample amounts required for analysis.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.6
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• pp.386-391
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• 2006

This study was conducted to evaluate the indole acetic acid (IAA) formation in soils as a biological indicator for the health of rice paddy soils with control, nitrogen sole, chemical fertilizer (NPK), and chemical fertilizer plus compost (CNPK) plots. There was a positive relationship between colorimetric method and high performance liquid chromatography for IAA in soils determined, and the values were similar between two methods, as $0.83{\sim}1.23{\mu}g\;IAA\;g^{-1}h^{-1}$ in colorimetric method, $0.80{\sim}1.29{\mu}g\;IAA\;g^{-1}h^{-1}$ in HPLC method. Numbers of dehydrogenase-producing bacteria and the IAA production in soils were high in NPK and CNPK plots comparing with control and nitrogen sole plots. Also there was high correlation between numbers of dehydrogenase-producing bacteria and IAA production in soils.

• Journal of the Korean Chemical Society
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• v.42 no.4
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• pp.411-415
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• 1998

In the present study, we were evaluated cytotoxic effects of epigallocatechin gallate in human skin melanoma cells such as HTB-69. The light microscopic study showed morphological changes of the treated cells. Disruptions in cell organelles were determined by colorimetric methods; 3-(4,5-dimethyl thiazol-2-yl)-2,5diphenyl-2H-tetrazolium bromide (MTT) assay, neutral red (NR) assay and sulforhodamine B protein (SRB) assay. These results suggest that epigallocatechin gallate retains a potential antitumor activity.

• Journal of Food Hygiene and Safety
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• v.21 no.2
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• pp.82-91
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• 2006

Standard and lead limit test in general test method of Korea, Japan, Joint FAO/WHO Expert Committee of Food Additives (JECFA), USA, and EU on synthetic and natural food additives were compared. There were found that the general test methods in 'Korea Food Additives Code' were different from standards of various institutes on lead limit test. For the lead limit test of food additives, Korea used dithizone method, Japan used atomic absorption spectrophotometry, and USA used dithizone method, flame atomic absorption spectrophotometric method, atomic absorption spectrophotometric graphite furnace method, and APDC extraction method. In addition, JECFA and EU used dithizone method and atomic absorption spectrophotometric method. The dithizone methods of Korea, USA, and JECFA were nearly identical. In the case of USA, JECFA, and EU, the analytical methods for lead limit test were shown in individual monograph. Lead limit test against 13 synthetic, such as magnesium stearate and L-cystine, and 12 natural, such as gua gum and diatomaceous earth, food additives distributed in Korea were performed by the analytical method of each institute. Although all institutes use various methods for analysis of lead, contents of lead in food additives tested fell into the standard of each institute.

• Korean Journal of Food Science and Technology
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• v.4 no.4
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• pp.235-238
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• 1972

A biuret method by Johnson and Craney (1971) was slightly modified and applied to the multiple analysis of nitrogen in brown rice. The results were compared with those by the dye-binding method to see if the former be applicable to the determination of higher nitrogen content in rice. The nitrogen content of rice samples ranged from $1.2{\sim}2.0%$. The correlation between biuret absorbance and nitrogen content was highly significant; its correlation coefficient being 0.841. The biuret method, however, showed rather lower correlation coefficient in case of high nitrogen samples.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.2
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• pp.162-169
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• 2018

The purpose of this study was to compare the validity of $Cariview^{(R)}$, a new colorimetric caries activity test, with $CRT^{(R)}$ bacteria, a conventional bacterial culture method. In addition, this study assesses the correlation between the dental caries experience and activity between mothers and their children. 34 pairs of mothers and their children under the age of 6 years participated in this study with informed consent. After filling out a questionnaire and oral examination, the two caries activity tests above were performed on each subject. In the results, $Cariview^{(R)}$ scores were statistically significant with children's caries experience (r = 0.598, p < 0.01) and showed higher correlation than $CRT^{(R)}$ bacteria scores. $Cariview^{(R)}$ scores showed statistically significant correlation with the number of decayed teeth in both mothers and children (p < 0.05). In both $Cariview^{(R)}$ and $CRT^{(R)}$ bacteria tests, there was no statistically significant correlation between caries experience and caries activity (p > 0.05). $Cariview^{(R)}$ colorimetric test will be clinically useful for predicting future caries risk and establishing a preventative strategy in pediatric dentistry.

• Korean Journal of Food Science and Technology
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• v.6 no.2
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• pp.56-60
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• 1974

A survey of the available methods for the determination of piperine was made, and a new method, developed based upon alkaline hydrolysis at about $140^{\circ}C$ followed by colorimetric determination of the liberated piperidine. Piperidine on treatment with p-nitrophenyl diazonium fluoborate reagent gives a red colored complex which has an adsorption maximum at 530nm. The method measures the total pungency in pepper and applicaple to piperine of black pepper and oleoresin of black pepper. The advantage of the present method is that the pungent compounds can be determined in micro samples.