• Korean Journal of Food Science and Technology
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• v.45 no.3
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• pp.285-292
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• 2013

This study was carried out to validate the safety of ametoctradin residues in agricultural commodities by developing an official analysis method. An analytical method was developed and validated using HPLC-PDA detectors. The samples were extracted with methanol, subsequently partitioned with dichloromethane and purified with florisil column chromatograph using acetone/hexane (30/70, v/v) as solvent. The method was validated by using grape, hulled rice, mandarin, and potato spiked with ametoctradin at 0.05 and 5.0 mg/kg, and pepper at 0.05 and 2.0 mg/kg. Average recoveries were 76-114.8% with relative standard deviation less than 10%, and the limit of detection and limit of quantification were 0.0125 and 0.05 mg/kg, respectively. The result of recoveries and overall coefficient of variation of the laboratory results from Gwangju regional Food and Drug Administration (FDA) and Daejeon regional FDA was accorded with Codex Alimentarius Commission Guideline (CAC/GL 40). Based on these results, this method was found to be appropriate for ametoctradin residue determination and can be used as the official method of analysis.

• Korean Journal of Agricultural and Forest Meteorology
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• v.13 no.4
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• pp.176-184
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• 2011

Cold air on sloping surfaces flows down to the valley bottom in mountainous terrain at calm and clear nights. Based on the assumption that the cold air flow may be the same as the water flow, current models estimate temperature drop by regarding the cold air accumulation at a given location as the water-like free drainage. At a closed catchment whose outlet is blocked by man-made obstacles such as banks and roads, however, the water-like free drainage assumption is no longer valid because the cold air accumulates from the bottom first. We developed an empirical model to estimate quantitatively the effect of cold pool on nocturnal temperature in a closed catchment. In our model, a closed catchment is treated like a "vessel", and a digital elevation model (DEM) was used to calculate the maximum capacity of the cold pool formed in a closed catchment. We introduce a topographical variable named "shape factor", which is the ratio of the cold air accumulation potential across the whole catchment area to the maximum capacity of the cold pool to describe the relative size of temperature drop at a wider range of catchment shapes. The shape factor is then used to simulate the density profile of cold pool formed in a given catchment based on a hypsometric equation. The cold lake module was incorporated with the existing model (i.e., Chung et al., 2006), generating a new model and predicting distribution of minimum temperature over closed catchments. We applied this model to Akyang valley (i.e., a typical closed catchment of 53 $km^2$ area) in the southern skirt of Mt. Jiri National Park where 12 automated weather stations (AWS) are operational. The performance of the model was evaluated based on the feasibility of delineating the temperature pattern accurately at cold pool forming at night. Overall, the model's ability of simulating the spatial pattern of lower temperature were improved especially at the valley bottom, showing a similar pattern of the estimated temperature with that of thermal images obtained across the valley at dawn (0520 to 0600 local standard time) of 17 May 2011. Error in temperature estimation, calculated with the root mean square error using the 10 low-lying AWSs, was substantially decreased from $1.30^{\circ}C$ with the existing model to $0.71^{\circ}C$ with the new model. These results suggest the feasibility of the new method in predicting the site-specific freeze and frost warning at a closed catchment.

• Journal of Food Hygiene and Safety
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• v.30 no.2
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• pp.143-149
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• 2015

This study was conducted to simultaneous analysis methods for water soluble vitamins B group (vitamin $B_1$, vitamin $B_2$, nicotinic acid, nicotinamide, vitamin $B_6$) which is used as health functional foods etc. Analytical methods of water-soluble vitamins B group by HPLC were established through instrumental analytical conditions, and the examination of data such as domestic and foreign reliable methods, and papers of journal. HPLC method analyzing water soluble vitamins B group was established using Capcell Pak C18 UG 120 column in 270 nm through test of columns. The validation has been performed on the method to determine linearity, accuracy, limits of quantification (LOQ) and repeatability for water soluble vitamins B group. An excellent linearity ($r^2=0.999$) was observed for vitamin $B_1$, vitamin $B_2$, nicotinic acid, nicotinamide, vitamin $B_6$ in the concentration range ($0.1{\sim}2{\mu}g/mL$). Observed recovery of vitamin $B_1$ was found to be between 100 and 103%, vitamin $B^2$ was found to be between 104 and 112%, nicotinic acid was found to be between 82 and 85%, nicotinamide was found to be between 121 and 124% and vitamin $B_6$ was found to be between 95 and 104%. LOQ of vitamin $B_1$ was found to be $0.04{\mu}g/mL$, vitamin $B_2$ was found to be $0.05{\mu}g/mL$, nicotinic acid was found to be $0.15{\mu}g/mL$, nicotinamide was found to be $0.08{\mu}g/mL$ and vitamin $B_6$ was found to be $0.63{\mu}g/mL$. Repeatability precision for vitamin $B_1$ was found to be 0.4%, vitamin $B_2$ was found to be 0.4%, nicotinic acid was found to be 0.5%, nicotinamide was found to be 0.7% and vitamin $B_6$ was found to be 0.4% relative standard deviation (RSD). Also, verify the accuracy of the simultaneous analysis methods, we monitored the labeled contents of the health functional foods and children's preferred foods.

• Journal of Food Hygiene and Safety
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• v.32 no.4
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• pp.298-305
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• 2017

Benzovindiflupyr is a new pyrazole carboxamide fungicide that inhibits succinate dehydrogenase of mitochondrial respiratory chain. This study was carried out to develop an analytical method for the determination of benzovindiflupyr residues in agricultural commodities using LC-MS/MS. The benzovindiflupyr residues in samples were extracted by using acetonitrile, partitioned with dichloromethane, and then purified with silica solid phase extraction (SPE) cartridge. Correlation coefficient ($r^2$) of benzovindiflupyr standard solution was 0.99 over the calibration ranges ($0.001{\sim}0.5{\mu}g/mL$). Recovery tests were conducted on 5 representative agricultural commodities (mandarin, green pepper, potato, soybean, and hulled rice) to validate the analytical method. The recoveries ranged from 79.3% to 110.0% and then relative standard deviation (RSD) was less than 9.1%. Also the limit of detection (LOD) and limit of quantification (LOQ) were 0.0005 and 0.005 mg/kg, respectively. The recoveries of interlaboratory validation ranged from 83.4% to 117.3% and the coefficient of variation (CV) was 9.0%. All results were followed with Codex guideline (CAC/GL 40) and Ministry of Food and Safety guideline (MFDS, 2016). The proposed new analytical method proved to be accurate, effective, and sensitive for benzovindiflupyr determination and would be used as an official analytical method.

• Korean Journal of Food Science and Technology
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• v.42 no.1
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• pp.27-32
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• 2010

This study was conducted to monitor aflatoxins in various medicinal herbs, providing available data for the safety of those products. To monitor aflatoxins in medicinal herbs, a total of 400 samples of 40 different herbs were collected in commercial retailers in Seoul, Daejeon, Gwangju, Daegu, and Busan from March to August, 2008. The samples that passed the sensory evaluation were tested for aflatoxins. Aflatoxins in samples were analyzed by HPLC-florescence coupled with photochemical enhancement. Samples were extracted with 70% methanol and then diluted to the appropriate concentration. A refining process was performed using an immunoaffinity column. The analytical method used in this study was validated. The $R^2$ value for aflatoxin $B_1$ was 0.99946, and the detection range was from 0.25 to 10.0 ng/mL. The accuracy of the analysis was ranged from 83.2% to 101.8%. The relative standard deviation (RSD) in the aflatoxin $B_1$ analysis was 3.4%, demonstrating the precision of this method. In addition, the detection limit and quantitative analysis limit of aflatoxin $B_1$ was $0.53\;{\mu}g/kg$ and $1.76\;{\mu}g/kg$, respectively. These results indicated that the analytical method used in this study was appropriate. The results of HPLC showed that 1% (4 samples) of the samples may contain aflatoxins. The concentration of quantified aflatoxin was $2.3\;{\mu}g/kg$ for both Quisqualis fructus and Remotiflori radix samples. The other samples were below the limit of quantification. Moreover, the concentration of aflatoxin $B_1$ which is made by specific fungi were below the level of regulation. Only 20% of aflatoxin $B_1$ were transferred to hot water. Therefore, the levels of aflatoxins in medicinal herbs were considered to be safe especially considering the aflatoxin transfer ratio.

• Analytical Science and Technology
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• v.27 no.5
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• pp.234-242
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• 2014

Imicyafos which is a nematicide for controlling root-knot nematodes has been registered in the Republic of Korea in 2012, and the maximum residue limits of imicyafos are set to watermelon and korean melon as each 0.05 mg/kg. Extremely reliable and sensitive analytical method is required for ensuring food safety on imicyafos residues in agricultural commodities. Imicyafos residues in samples were extracted with acetone, partitioned with hexane and dichloromethane, and then purified with florisil. The purified samples were analyzed by HPLC-UVD and confirmed with LC-MS. Linear range was between 0.1~5 mg/kg with the correlation coefficient ($r^2$) 0.99997. Average recoveries of imicyafos ranged from 77.0 to 115.4% at the spiked levels of 0.02 and 0.05 mg/kg with the relative standard deviations of 2.2~9.6%. Limit of detection and quantification were 0.005 and 0.02 mg/kg, respectively. An inter-laboratory study was conducted to validate the determination method in depth, and the results were satisfactory. All of the validation results revealed that the developed analytical method in this study is relevant for imicyafos determination in agricultural commodities and will be used as an official analytical method.

• Korean Journal of Environmental Agriculture
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• v.34 no.4
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• pp.318-327
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• 2015

BACKGROUND: Trinexapac-ethyl is a plant growth regulator (PGR) that inhibits the biosynthesis of plant growth hormone (gibberellin). It is used for the prevention of lodging, increasing yields of cereals, and reducing mowing of turf. The experiment was conducted to establish a determination method for trinexapac-ethyl and its metabolites trinexapac in agricultural products using LC-MS/MS.METHODS AND RESULTS: Trinexapac-ethyl and trinexapac were extracted from agricultural products with methanol/ distilled water and the extract was partitioned with dichloromethane and then detected by LC-MS/MS. Limit of detection(LOD) was 0.003 mg/kg and limit of quantification(LOQ) was 0.01 mg/kg, respectively. Matrix matched calibration curves were linear over the calibration ranges (0.01-1.0 mg/L) for all the analytes into blank extract withr²> 0.997. For validation purposes, recovery studies were carried out at three different concentration levels (LOQ, 10LOQ, 50LOQ,n=5). Recoveries of trinexapacethyl and trinexapac were within the range of 73.6-106.9%, 72.7-99.2%, respectively. The relative standard deviations (RSDs) were less than 9.0%. All values were consistent with the criteria ranges requested in the CODEX guideline(CAC/GL 40, 2003).CONCLUSION: The proposed analytical method was accurate, effective and sensitive for trinexapac-ethyl and trinexapac determination and it can be used to as an official method in Korea.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.4
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• pp.235-242
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• 2006

The precise estimation of total and organic carbon contents in sediments is fundamental to understand the benthic environment. To test the precision and accuracy of CHN analyzer and the procedure to quantify total and organic carbon contents(using in-situ acidification with sulfurous acid($H_2SO_3$)) in the sediment, the reference material s such as Acetanilide($C_8H_9NO$), Sulfanilammide($C_6H_8N_2O_2S$), and BCSS-1(standard estuary sediment) were used. The results indicate that CHN analyzer to quantify carbon and nitrogen content has high precision(percent error=3.29%) and accuracy(relative standard deviation=1.26%). Additionally, we conducted the instrumental comparison of carbon values analyzed using CHN analyzer and Coulometeric Carbon Analyzer. Total carbon contents measured from two different instruments were highly correlated($R^2=0.9993$, n=84, p<0.0001) with a linear relationship and show no significant differences(paired t-test, p=0.0003). The organic carbon contents from two instruments also showed the similar results with a significant linear relationship($R^2=0.8867$, n=84, p<0.0001) and no significant differences(paired t-test, p<0.0001). Although it is possible to overestimate organic carbon contents for some sediment types having high inorganic carbon contents(such as calcareous ooze) due to procedural and analytical errors, analysis of organic carbon contents in sediments using CHN Analyzer and current procedures seems to provide the best estimates. Therefore, we recommend that this method can be applied to measure the carbon content in normal any sediment samples and are considered to be one of the best procedure far routine analysis of total and organic carbon.

• Journal of Oral Medicine and Pain
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• v.36 no.3
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• pp.187-197
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• 2011

Temporomandibular disorders(TMD) is a collective term which is embracing a number of clinical problems that involve the masticatory musculature, the TMJ and associated structures, or both. Myofascial pain, which is a kind of masticatory muscle disorder of TMD, is the sensory, motor, and autonomic symptoms caused by myofascial trigger points. There has been some controversies regarding etiologies of TMD and MFP. Especially the issue of occlusal conditions has been a critical issue for long time. Despite much efforts, the results of studies regarding occlusal conditions were contradictory. These controversies might be mostly due to various factors resulting from the complex nature of TMD, however, inaccurate and inappropriate study design, selection criteria, methodologies also play significant roles. Recently, a computerized occlusal analysis system, T-Scan II which made it possible to reveal quantifiable time data and relative force data for analyzing occlusion, was introduced. Some authorities suggested that the concept of disclusion time and prolonged disclusion time of posterior tooth and MFP are related using T-Scan II. But the previous studies which used T-SCAN II are not reliable for they did not provide accurate diagnostic criteria of MFP. Morever they did not compare with controls, and had many other problems. The purpose of this study was to evaluate the relationship between MFP and prolonged disclusion time of posterior tooth, which is one of the occlusal factors of TMD, by selecting 30 subjects as the study group through strict criteria and comparing them with 38 controls using T-SCAN II, computerized occlusal analysis system. The results, statistically analyzed, are summarized as follows: 1. Cronbach ${\alpha}$ coefficient of repeated measurements of disclusion time was 0.92. 2. There were no statistically significant differences at repeated measured disclusion time of both side between control and study group. 3. There was no statistically significant diffefence in the disclusion time between right and left side. From the results above, we can suggest that there was no relationship between MFP and disclusion time, so irreversible treatments leading to the reduction of disclusion time for treating MFP would not be appropriate. However more controlled, large scaled study, which consider various occlusal factors, and quantification of symptoms using Helkimo index would be necessary in the future.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.9
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• pp.1378-1386
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• 2013

Atopic dermatitis (AD) is a common skin disease characterized by chronic and relapsing inflammatory dermatitis with immunological disturbances. In spite of the continuous increase in the incidence of AD, it is regrettable that till date there is no effective treatment to treat the same. Therefore, the present study was designed to examine the possible anti-atopic effects of Castanea crenata inner shell extracts fermented by Lactobacillus bifermentans (FCS) in 2,4-dinitrochlorobenzene (DNCB) induced AD in NC/Nga mice. Based on the results of HPLC analysis, we found that FCS contains anti-inflammatory factors such as gallic acid (10.18 mg/g) and ellagic acid (2.14 mg/g). The groups that we have used in this study included 0.1%, 1%, 5% fermented Castanea crenata inner shell extracts (FCS 0.1, FCS 1, FCS 5), 1,3-butylene glycol treated control (AD), and normal mice. After topical FCS treatment, we observed that the clinical severity score for AD was lower in both the FCS 1 and FCS 5 groups than the AD group. We also proved beyond doubt that there was improvement of melanin, erythema and skin moisture indices in the FCS 5 group. Spleen index and gene expression levels of pro-inflammatory cytokines such as IL-$1{\beta}$ and TNF-${\alpha}$ were significantly decreased in the FCS 5 group compared to the AD group (P<0.05). Further, we also found that the level of serum immunoglobulin E (IgE) in the FCS-treated group was decreased in a concentration-dependent manner. The results of our study suggest that FCS can be effectively used as a cosmeceutical ingredient for both the prevention and improvement of AD.