• Nuclear Medicine and Molecular Imaging
• /
• v.43 no.5
• /
• pp.451-458
• /
• 2009

Purpose: Optical molecular luminescence imaging is widely used for detection and imaging of bio-photons emitted by luminescent luciferase activation. The measured photons in this method provide the degree of molecular alteration or cell numbers with the advantage of high signal-to-noise ratio. To extract useful information from the measured results, the analysis based on a proper quantification method is necessary. In this research, we propose a quantification method presenting linear response of measured light signal to measurement time. Materials and Methods: We detected the luminescence signal by using lab-made optical imaging equipment of animal light imaging system (ALIS) and different two kinds of light sources. One is three bacterial light-emitting sources containing different number of bacteria. The other is three different non-bacterial light sources emitting very weak light. By using the concept of the candela and the flux, we could derive simplified linear quantification formula. After experimentally measuring light intensity, the data was processed with the proposed quantification function. Results: We could obtain linear response of photon counts to measurement time by applying the pre-determined quantification function. The ratio of the re-calculated photon counts and measurement time present a constant value although different light source was applied. Conclusion: The quantification function for linear response could be applicable to the standard quantification process. The proposed method could be used for the exact quantitative analysis in various light imaging equipments with presenting linear response behavior of constant light emitting sources to measurement time.

• Korean Journal of Environmental Agriculture
• /
• v.36 no.4
• /
• pp.249-255
• /
• 2017

BACKGROUND: Globally, mulberry (Morus sp.) is exploited for feeding leaf to silkworms in order to obtain silk fiber or for animal feedstock production. Also, mulberry fruit is known to a by-product that was produced from mulberry tree after harvesting leaves for silkworm rearing, as a yield and consumption of mulberry fruit was increased, it has been fixing to a newincome crop. Mulberry leaves and fruits are used for the health benefits of human beings. Mulberry contains various bioactive components, such as alkaloids and flavonoids. Mulberry flavonoids are an important part of the diet because of their effects on human nutrition. The flavonoids in mulberry leaf and fruit of 'Suhyang'(Morus alba L.) were determined. METHODS AND RESULTS: Flavonoids for mulberry leaf and fruit of 'Suhyang' were analysed using ultrahigh performance liquid chromatography coupled with diode array detection and quadrupole time-of-flight mass spectrometry (UPLC-DAD-QTOF/MS)technique. An UPLC-DAD-QTOF/MS system was used, and identification of mulberry leaves constituents was carried out on the basis of the complementary information obtained from LC spectra, MS ions, and MS/MS fragments. The mulberry leaf (16 flavonoids) and fruit (9 flavonoids) were isolated and analyzed from Suhyang using UPLC-DAD-QTOF/MS chromatogram. To the best of our knowledge, Quercetin 3-O-(6"-O-malonyl) glucoside and quercetin 3-O-rutinoside (rutin) was detected on the highest content in leaf and fruit, respectively and further research will be devoted to evaluate their biological activity. CONCLUSION: Obtaining information about the concentration of functional materials in mulberry leaves could contribute to the development and promotion of processed, functional products and offer possible industrial use of 'Suhyang', holding promises to enhance the overall profitability of sericulture.

• Journal of Food Hygiene and Safety
• /
• v.27 no.1
• /
• pp.37-41
• /
• 2012

The current standard for testing tetrodotoxin (TTX) in foodstuffs is the mouse bioassay (MBA) in Korea as in many other countries. However, this test suffers from potential ethical concerns over the use of live animals. In addition, the mouse bioassay does not test for a specific toxin thus a sample resulting in mouse incapacitation would need further confirmatory testing to determine the exact source toxin (e.g., TTX, STX, brevotoxin, etc.). Furthermore, though the time of death is proportional to toxicity in this assay, the dynamic range for this proportional relationship is small thus many samples must be diluted and new mice be injected to yield a result that falls within the quantitative dynamic range. Therefore, in recent years, there have been many efforts in this field to develop alternative assays. High performance liquid chromatography (HPLC) coupled with mass spectrometry (MS) has been emerged as one of the most promising options. A LC-MS-MS method involves solid-phase extraction (SPE) and followed by analysis using an electrospray in the positive ionization mode and multiple reactions monitoring (MRM). To adopt LC-MS-MS method as alternative standard for testing TTX, we performed a validation study for the quantification of TTX in puffer fish. This LC-MS-MS method showed good sensitivity as limits of detection (LOD) of $0.03{\sim}0.08{\mu}g/g$ and limits of quantification (LOQ) of $0.10{\sim}0.25{\mu}g/g$. The linearity ($r^2$) of tetrodotoxin were 0.9986~0.9997, the recovery were 80.9~103.0% and the relative standard deviations (RSD) were 4.3~13.0%. The correlation coefficient between the mouse bioassay and LC/MS/MS method was higher than 0.95.

• Analytical Science and Technology
• /
• v.29 no.5
• /
• pp.234-241
• /
• 2016

The approach presented in this article refers to the bioanalytical method validation for the detection and quantitative determination of arsenic species including arsenite (As(III)), arsenate (As(V)), dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) in dog plasma by high-performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP/MS). The arsenic species were separated using an agilent As speciation column by a mobile phase of 2 mM sodium phosphate monobasic, 0.2 mM ethylenediaminetetraacetic acid disodium salt dehydrate, 10 mM sodium acetate, 3 mM sodium nitrate and 1 % ethyl alcohol at pH 11 (adjusted with 1M NaOH). The method validation experiment was obtained selectivity, linearity, accuracy, precision, matrix effect, recovery, system suitability, dilution integrity and various stabilities. All calibration curves showed good linearity (R²>0.999) within test ranges. The lower limit of quantitation (LLOQ) was 5 ng/mL for As(III), As(V) and DMA, and 20 ng/mL for MMA. The system suitability and dilution values were within 6.5 % and 7.7 %. Subsequently, the developed and validated HPLC-ICP/MS method was also successfully applied to determine the arsenic speciation in dog plasma samples, and the recoveries for the spiked samples were in the range of 91.5–102.2 %. Therefore, this method could be applied to the evaluation of arsenic exposure, health effect assessment and other bio-monitoring studies in biological samples.

• Analytical Science and Technology
• /
• v.30 no.5
• /
• pp.295-302
• /
• 2017

This study presents a method validation for extraction and quantitative analysis of levulinic acid in soy sacues using high performance liquid chromatograph-photodiode array detector (HPLC-PDA). The levulinic acid in samples were extracted with distilled water, and then purified with C18 Sep-Pak cartridge. The calibration curves showed good linearity (R > 0.999) in a relatively wide concentration range ($2.5-400{\mu}g/mL$). Mean recoveries and relative standard deviation (RSD) of levulinic acid spiked in soy sauce samples at different spiking levels ($2.5-400{\mu}g/mL$; 6 point). Recoveries were 87.58-97.26 % with RSD less than 15 %, and limit of detection (LOD) and limit of quantification (LOQ) were 0.64 and $1.64{\mu}g/mL$, respectively. According to monitoring result with the established method, levulinic acid was found in 43 of 59 domestic commercial soy sauces, soy sauce based sauces and seasoned meats. The contamination levels were 0.44-1.23 mg/mL for soy sauces, 0.03-0.83 mg/mL for soy sauce based sauces and 8.43-38.94 mg/mL for seasoned meats. The results indicated to be rapidly and accurately qualifying levulinic acid and can be used as a suitable quality control method for soy sauce and soy sauce related commodities.

• Journal of Food Hygiene and Safety
• /
• v.6 no.1
• /
• pp.13-26
• /
• 1991

This study was performed for searching for non-hepatectomy medium-term bioassay model by using newborn female rats. Newborn female Sprague-Dawley rats (1 day old) were given an intraperitoneal injection of 150 mg/kg of diethylnitrosamine (DENA). After three weeks, all rats were weaned and divided into three groups. Group 1 were fed on diets containing 0.01% 2-acetylaminofluorene (2-AAF) as a promoter for three weeks. Group 2 were given 0.05% phenobarbital (PB) in drinking water as a promoter for 8 weeks. Group 3 was control group. The autopsy was carried out at 4 weeks and 8 weeks after weaning. Preneoplastic lesions were indentified with immunohistochemical staining for glutathione S-transferase placental form (GST-P). In liver weight to body weight ratios, group 2 showed significant difference from group 1 (p<0.001) at 4 weeks after weaning. Group 1 and group 2 showed significant difference from group 3 at 8 weeks after weaning (p<0.0I, p<0.001), respectively. In quantitative analysis for GST-P positive lesion area by using Image Analyzer, group 1 and group 2 represented significant difference in comparison with group 3 at early 4 weeks after weaning (p

• Journal of Life Science
• /
• v.16 no.6
• /
• pp.1006-1013
• /
• 2006

To High Throughput Screening (HTS), a homogeneous fluorescence polarization immunoassay (FPIA) was developed for the quantitative determination of ochratoxin A(OTA) using a $Victor^3$ (PerkinElmer). The homologous tracer, fluorescein-labelled OTA-EDF were synthesized and a specific OTA antibody has been used in the development of the method. It allowed the determination of OTA in the concentration range 0.5-200 ng/ml, with the detection limit of 0.3 ng/ml. The method developed was highly specific and reproducible. OTA spikes in unpolished rice extracts were determinable by FPIA with good recovery. For naturally contaminated unpolished rice samples some disagreement was observed between the results obtained by FPIA and HPLC, which could be related to the a little matrix effect observed for FPIA. Further research is needed to validate the procedure. On the basis of these initial results, this FPIA appears to meet the performance criteria for OTA screening of food samples without a complicated clean-up.

• Korean Journal of Food Science and Technology
• /
• v.35 no.5
• /
• pp.764-768
• /
• 2003

Resveratrol is natually occurring phytoalexin compounds produced by grape berries, peanuts, and their products in response to stress such as fungal infection, heavy metal ions or UV irradiation. The objective of this study was to develop a reliable high-performance liquid chromatographic method for the quantitative determination of trans-resveratrol in grape and its products. The trans-resveratrol was separated isocratically on Nucleosil 100-5 C18 column, using a mobile phase containing acetonitrile : water (40 : 60, v/v), detected by UV detector at 306 nm and the flow rate was 0.3 mL/min. Under this analytical condition, the recoveries of trans-resveratrol in grape, wine, and grape juice were 92.35, 104.72, and 91.08, respectively. Limit of detection in grape, wine, and grape juice were 14.5 ng/g, 3.62 ng/mL, and 4.02 ng/mL. Also, limit of quantitation in grape, wine, and grape juice were 14.8 ng/g, 3.69 ng/mL, and 4.10 ng/mL. Assay values of 32 grape varieties, 9 wines, and 9 grape juices were ranged from trace amount to $207.1\;{\mu}g/100\;g$, from 5.4 to $275.7\;{\mu}g/L$, and from 63.3 to $751.6\;{\mu}g/L$, respectively.

• Journal of Radiation Protection and Research
• /
• v.38 no.1
• /
• pp.29-36
• /
• 2013

The aim of this study was to determine the correlation between exposure index (EI) and dose factors related to radiation dose optimization in digital radiography (DR) system. Two phantoms with built-in regional test object for quantitative assessment of images were used to produce image signals that acquired in chest radiography background. EI and entrane surface dose (ESD) increased proportionally with rise of radiation dose (kVp, mAs) in both DR and CR systems. Especially, DR detector was effective to form good contrast and hence, reached easily to improvement of image quality with minimal dose changes. It made operators possible to expect the accuracy of EI values deeply related to absorbed dose of the detector. The evaluation of images was obtained specially employed calculation of noise to signal ratio (NSR) and contrast to noise ratio (CNR). These measurements were performed for how exposure factors affect image quality. NSR was inversely proportional to kVp and mAs and low NSR represented high signal detection efficiency. Consequently, EI values was the measure of the amount of exposure received by the image receptor and it was proportional to exposure factors. Therefore the EI in a recommended range from manufacturer can offer optimal image quality. Also, continuous monitoring of EI values in the digital radiography can reduce the unnecessary patient dose and help the quality control of the system.

• Journal of the Korean Electrochemical Society
• /
• v.17 no.3
• /
• pp.172-178
• /
• 2014

In this work, we describe an electrochemical immunosensor for simple, fast and quantitative detection of a urinary hippuric acid (HA). Urinary HA, of molecular weight 180 DA, is one of the major metabolites and biological indicators in toluene-exposed humans. Simple and ubiquitous monitoring of exposure to toluene is very important in occupational health care. We propose the electrochemical immunoassay based on the dopamine-antigen conjugate for detecting hippuric acid. Our electrochemical immunoassay system employs a conjugate of dopamine (DA) as an electrochemical active molecule and hippuric acid (HA) as an antigen. As an electrochemical aspect, dopamine (DA) containing two hydroxyl group can show excellent redox signal. Also, dopamine-tethered hippuric acid (DA-HA) shows the reversible redox signal in the immunoassay. The competition between HA and DA-HA generated electric signals proportional to HA concentration. The electrochemical immunoassay was performed with DA-HA on the screen printed carbon electrodes (SPCEs), and then applies the mixture antigen (HA) and HA-antibody. The electrical signals were proportional to HA in the range of 0.010~2.500 mg/mL which is enough range to be used for the point-of-care.