• Applied Biological Chemistry
• /
• v.47 no.1
• /
• pp.113-119
• /
• 2004

Persistence of the triazole fungicides, bitertanol and tebucnazole was investigated after their application at recommended and double rate on greenhouse-grown peppers. The half-life of bitertanol and tebuconazole on peppers at recommended and double rate was $5.2{\sim}6.1$ and $4.6{\sim}5.2$ days, respectively. Half-lives of bitertanol and tebuconazole on pepper leaves $(16.8{\sim}22.5\;days)$ was longer than those in the peppers. Residual concentration of bitertanol and tebuconazole on pepper leaves 24 days after application were 10.1 and 17.5 mg/kg, respectively, and these levels were higher than MRL which had been established at 3.0 and 5.0 mg/kg in Korea. Pattern of dissipation was well fitted to the first-order kinetics. In household washing experiment with surfactant, dislodgeable portions on pepper leaves of bitertanol and tebuconazole were occupied 36% and 48% of the residues found 24 days after application.

• Korean Journal of Food Science and Technology
• /
• v.49 no.4
• /
• pp.349-354
• /
• 2017

The geographical origins of raw ginseng (RG) were discriminated using an electronic tongue. Taste screening, DFA (discriminant function analysis), and CDA (canonical discriminant analysis) were used to statistically analyze the data. The taste profile patterns of umami, bitterness, and sweetness of the Korean RG was different from those of the Chinese RG. The Korean RG was stronger than the Chinese RG regarding the taste of umami. DFA discriminated the geographical origins of 154 samples, with a few overlapping samples, between the Korean and Chinese RG. CDA showed that the accuracy of origin discrimination for the Korean and Chinese RGs were 87.01 and 94.81%, respectively. The final accuracy of origin discrimination was 90.91%. The distance between the centroids of each group was 2.7463. Thus, the electronic tongue analysis can be used to efficiently differentiate the geographical origins of RG.

• Korean Journal of Environmental Agriculture
• /
• v.40 no.2
• /
• pp.92-98
• /
• 2021

BACKGROUND: Unintentional residual pesticide in soil derived from preceding crops and the transfer to succeeding crops was considered a critical barrier for positive list system (PLS). Thus, an uncertain risk is predicted for ethoprophos applied at cultivation of preceding crop (Korean cabbage) to succeeding crop (spinach). METHODS AND RESULTS: Ethoprophos was treated on soil following the recommended dose and 5 times dose according to the safe use guidelines for Korean cabbage after seeding. On the 4 days after harvesting of preceding crop, spinach was sowed. The initial residual amounts of ethoprophos on soil (7.081-19.493 mg/kg) were decreased to 3.832-7.218 mg/kg until the harvest of Korean cabbage, and then finally decreased to 0.011-0.079 mg/kg after spinach cultivation. The uptake rates of ethoprophos from soil by Korean cabbage were 0.01-0.03% and distributed to root (0.150-0.903 mg/kg) and shoot (0.021-0.151 mg/kg), respectively. The residual amounts of uptake and translocation from preceding crop cultivated soil to spinach edible part were found to be below LOQ. CONCLUSION: The plant back internal (PBI) for ethoprophos is not recommended during sequential cultivation of leafy vegetables, since the residual amounts of ethoprophos in spinach were less than MRL (0.02 mg/kg).

• The Korean Journal of Pesticide Science
• /
• v.11 no.3
• /
• pp.154-163
• /
• 2007

In order to elucidate the residual characteristics of some pyrethroid insecticides commonly used for Korean cabbage, such as bifentbrin, lambda-cyhalothrin and deltametbrin, the test pesticides were sprayed onto the crop at recommended rate and doubled rate of the recommendation. Their detection limits were 0.004 mg $kg^{-1}$ and mean recoveries at the fortification levels of 0.04 and 0.2 mg $kg^{-1}$ were from 95.16 to 99.32 and from 86.81 to 103.73%, respectively. Half-lives were from 2.5 to 3.6 at the recommended rate and from 2.3 to 3.9 days at the doubled rate of the recommendation. Initial residue amounts of bifenthrin and lambda-cyhalothrin at the recommended rate and doubled rate of recommendation and of deltamethrin at the recommended rate were less than their MRL, whereas, in case of deltamethrin sprayed at doubled rate of the recommendation, the residue level exceeded its MRL. However, the residue levels of the pesticides in the crop sampled at harvest were less than their maximum residue levels and the ratios of the estimated daily intake (EDI) to acceptable daily intake (ADI) for the pesticides tested calculated from the residue data at harvest were less than 7%, suggesting that these pesticides would be safe for Korean cabbage from the residue concern.

• Korean Journal of Environmental Agriculture
• /
• v.27 no.1
• /
• pp.92-98
• /
• 2008

This experiment was carried out to investigate the residue patterns of two insecticides, indoxcarb and thiamethoxam, commonly used for Chinese cabbage, under greenhouse conditions. The pesticides were sprayed onto Chinese cabbage at the recommended dose and double of the recommended dose 10 days before the prearranged harvest and then sampling was done at 0.17, 1, 2, 3, 4, 5, 6, 8, 10, and 12 days after spraying. The amounts of their residues in the crop were analyzed with an HPLC. The limit of detection(LOD) of both indoxacarb and thiamethoxam was 0.01 mg $kg^{-1}$ and mean recoveries of indoxacarb and thiamethoxam were from 97.91 to 104.36% and from 97.07 to 105.49%, respectively. Half-lives of indoxacarb and thiamethoxam were 3.4 and 2.3 days at the recommended dose and 3.3 and 3.5 days at the doubled dose, respectively. The ratios of the EDI to ADI by intake the crop harvested 10 days after spraying were less than 4% of their ADIs.

• The Korean Journal of Pesticide Science
• /
• v.9 no.3
• /
• pp.231-236
• /
• 2005

This study was conducted to determine the amounts of pesticide residues after treatment of criterion dose with 4 pesticides(tolclofos-m, folpet, procymidone, and triflumizole) under cultivated period and to compare the biological half-life of pesticides with 6 kinetic models(first, zero and second order kinetics, power function, elovich and parabolic model) and to establish proposed field tolerance using biological half-lives. Recovery of 4 pesticides form strawberry was ranged from 85.1 to 105.5%. For all of 4 pesticides, dissipation rate was over 73% at 5 days after application. Among 6 kinetic models, first order kinetic model (FO) was best fit to describe the relationship between residual pattern of pesticides and time. Therefore, half-lives were calculated by FO for establishing the field tolerance. These results showed that half-life should be calculated by comparative best fit kinetic model and field tolerance can help to prevent unacceptable agricultural products from marketing. It is good for both consumers and farmers having safe agricultural products and financial benefits, respectively.

• The Korean Journal of Pesticide Science
• /
• v.15 no.3
• /
• pp.246-253
• /
• 2011

This experiment was carried out to examine the residual amount variation of carbendazim and chlorpyrifos in fruit parts of red pepper according to the open field and/or the rain shelter house. It was shown higher residual amounts of agrochemicals in the field than the house condition at two hours (0 day) after chemical application, but it was shown higher residual amounts in the house at 5 days and 10 days. Although the residual amount in the field was higher than in the house at the beginning, the chemicals fast degraded in field condition. Carbendazim and chlorpyrifos remained as time passed in order of receptacle, but the residual amounts of two chemicals in leaf at $5^{th}$ day. Carbendazim and chlorpyrifos were lessened until 10 days after chemical application, and reduction rate were 19.1% and 66.4% in flesh, 45.2% and 62.3% in receptacle, and 41.6% and 72.0% in the stalk, respectively. The reduction rate at 15 days showed 31.1%, 75.3% in flesh, 43.5%, 81.7% in receptacle, and 47.7%, 82.8% in stalk, respectively. Therefore the reduction rate of carbendazim showed receptacle > stalk > flesh, and that of chlorpyrifos showed stalk > receptacle > flesh in order. The calculated half-life of carbendazim showed 29.6 days in flesh, 13.6 days in receptacle, and 16.0 days in stalk, but that of chlorpyrifos showed 8.3 days in flesh, 8.3 days in receptacle, and 6.3 days in stalk. In conclusion, the half-life of carbendazim was longer than that of chlorpyrifos in even part, and especially was longest in flesh part of fruit.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.63 no.2
• /
• pp.98-105
• /
• 2018

The sale of brown rice batches composed of rice produced in different years is prohibited in Korea. Thus, new methods for the identification of the year of production are critical for maintaining the distribution of high quality brown rice. Here, we describe the exploitation of an enzyme that can be used to discriminate between freshly harvested and one-year-old brown rice. The degree of enzyme activity was visualized through freshness test with Guaiacol, Oxydol, and p-phenylenediamine reagents. With electronic eye equipment, we selected 29 color codes for identifying new brown rice and old brown rice. The discrimination power of selected color codes showed a minimum of 0.263 to a maximum of 0.922 and an average value of 0.62. The accuracy with which new brown rice and old brown rice could be identified was 100% in principal component analysis (PCA) and discriminant function analysis (DFA). The DFA analysis had greater discriminatory power than did the PCA analysis. A verification test using new brown rice, old brown rice, or a mixture of the two was then performed to validate our method. The accuracy of identification of new and old brown rice was 100% in both cases, whereas mixed brown rice samples were correctly classified at a rate of 96.9%. Additionally, in order to test whether the discriminant constructed in winter can be applied to samples collected in summer, new and old brown rice stored for 8 months were collected and tested. Both new and old brown rice collected in summer were classified as old brown rice and showed 50% identification accuracy. We were able to attribute these observations to changes in enzyme content over time, and therefore we conclude, it will be necessary to develop discriminants that are specific to distinct storage periods in the near future.

• Korean Journal of Environmental Agriculture
• /
• v.24 no.2
• /
• pp.123-131
• /
• 2005

This study was focused on adsorption, leaching, photolysis, and hydrolysis of the fungicide procymidone in soils. Adsorption type of procymidone on three different soil were well fitted to Linear and Freundlich isotherm. Distribution coefficients (Kd) were ranged from 2.75 to 12.18 and Freundlich isotherm Kf value $1.99{\sim}9.98$, 1/n value $0.74{\sim}0.89$. Desorption rates were $20.1{\sim}34.0%$ (Namgye), $26.3{\sim}44.6%$ (Jigog) and $31.6{\sim}50.9%$ (Baegsan series) and desorption hysteresis were $0.65{\sim}0.79,\;0.55{\sim}0.73\;and\;0.49{\sim}0.68$. Procymidone seemed to be stable to photolysis in acidic and neutral solutions but hydrolyzed rapidly in alkaline solution. Considering leaching properties procymidone mobility low in soils.

• Journal of Food Hygiene and Safety
• /
• v.22 no.4
• /
• pp.353-358
• /
• 2007

Contamination of ochratoxin A (OTA) was studied in 194 compound feeds and 59 feed ingredients samples distributed in South KOREA in 2006 and 2007. The degree of OTA contamination in feed ingredients was 27%, and its detected levels were ranged from 0.27 to 3.39 ppb. Seventy six percent of compound feeds were contaminated with OTA at concentration between 0.21 and 13.64 ppb. The highest degree of OTA contamination was observed in compound feeds for dairy cattle (96%) followed by for poultry (85%) and swine (79%). Beef cattle exhibited the highest level of OTA contamination (2.2 ppb). Compound feeds for dairy cattle and feed ingredients for vegetable proteins showed relative lower level of contamination at 1.6 and 1.2 ppb, respectively.