• The Korean Journal of Pesticide Science
• /
• v.11 no.2
• /
• pp.106-116
• /
• 2007

Pesticide, chlorfluazuron was subjected to determine the safety of terminal residues at the harvesting date of perilla leaves cultivated in plastic house. After the pesticide applied on a foliar spray in 2005 and 2006, leaf persistence of its residue was analysed for 10 days before leaf harvest. The degradation rate of chlorfluazuron in the leaf was 32.3 %(standard application), 43.6 %(double application) and 78.0 %(standard), 80.4 %(double) at second and tenth day, respectively, under analysis of GC/ECD in 2005. The degradation rate of chlorfluazuron in the leaf was 33.1 %(GC/ECD analyze), 34.0 %(HPLC/UVD analyze) and 77.9 %(GC/ECD), 78.4 %(HPLC/UVD) at second and tenth day, respectively, under the standard level of pesticide in 2006. The biological half-life of the chlorfluazuron residue was estimated by the regression equation calculated from daily dissipation of pesticide in the perilla leaves. The longest half-life of the chlorfluazuron residue in perilla leaves was 5.5 days. The maximum residual limit(MRL) for chlorfluazuron based on the longest half-life was estimated 2.0ppm at harvesting day, 2.5ppm at second day and 7.1ppm at tenth day before leaf harvesting of perilla.

• The Korean Journal of Pesticide Science
• /
• v.15 no.3
• /
• pp.254-268
• /
• 2011

Fenoxycarb, pyriproxyfen and methoprene are juvenile hormone mimic insecticide. These insecticides have been widely used for mosquito, fly, scale insects, and Lepidoptera. The purpose of this study was to develop a simultaneous determination procedure of fenoxycarb, pyriproxyfen and methoprene residues in crops using HPLC-UVD/MS. These insecticide residues were extracted with acetone from representative samples of four raw products which comprised brown rice, apple, green pepper, and Chinese cabbage. The extract was diluted with saline water, and then n-hexane/dichloromethane partition was followed to recover these insecticides from the aqueous phase. Florisil column chromatography was additionally employed for final clean up of the extract. The analytes were quantitated by HPLC-UVD/MS, using a $C_{18}$ column. The crops were fortified with each insecticide at 3 levels per crop. Mean recovery ratios were ranged from 80.0 to 104.3% in four representative agricultural commodities. The coefficients of variation were less than 4.8%. Quantitative limit of fenoxycarb, pyriproxyfen, and methoprene was 0.04 mg/kg in crop samples. A HPLC-UVD/MS with selected-ion monitoring was also provided to confirm the suspected residues. The proposed simultaneous analysis method was reproducible and sensitive enough to determine the residues of fenoxycarb, pyriproxyfen and methoprene in the agricultural commodities.

• Korean Journal of Environmental Agriculture
• /
• v.31 no.2
• /
• pp.157-163
• /
• 2012

BACKGROUND: For the safety of imported agricultural products, the study was conducted to develop the analytical method of unregistered pesticides in domestic. The analytical method of 6 pesticides, chlorthal-dimethyl, clomeprop, diflufenican, hexachlorobenzene, picolinafen, and propyzamide, for a fast multi-residue analysis were established for two different type crops, orange and brown rice by GC-ECD and confirmed by mass spectrometry. METHODS AND RESULTS: The analytical method was evaluated to limit of quantification, linearity and recoveries. The crop samples were extracted with acetonitrile and performed cleanup by liquid-liquid partition and Florisil SPE to remove co-extracted matrix. The extracted samples were analyzed by GC-ECD with good sensitivity and selectivity of the method. The limits of quantification (LOQ) range of the method with S/N ratio of 10 was 0.02~0.05 mg/kg for orange and brown rice. The linearity for targeted pesticides were $R^2$ >0.999 at the levels ranged from 0.05 to 10.0 mg/kg. The average recoveries ranged from 74.4% to 110.3% with the percentage of coefficient variation in the range 0.2~8.8% at two different spiking levels (0.02 mg/kg and 0.2 mg/kg, 0.05 mg/kg and 0.5 mg/kg) in brown rice. And the average recoveries ranged from 77.8% to 118.4% with the percentage of coefficient variation in the range 0.2~6.6% at two different spiking levels (0.02 mg/kg and 0.2 mg/kg, 0.05 mg/kg and 0.5 mg/kg) in orange. Final determination was by gas chromatography/mass spectrometry/selected ion monitoring (GC/MS/SIM) to identify the targeted pesticides. CONCLUSION: As a result, this developed analytical method can be used as an official method for imported agricultural products.

• Journal of Life Science
• /
• v.22 no.11
• /
• pp.1456-1462
• /
• 2012

Sorafenib is a multikinase inhibitor and an oral anticancer drug approved for the treatment of patients with advanced renal cell carcinoma and those with unresectable hepatocellular carcinoma. The purpose of this study was to develop an efficient method of the determination of sorafenib in human plasma using tandem mass spectrometry coupled with liquid chromatography (LC/MS/MS) and validate the method by the guidelines of the Korean Food and Drug Administration (KFDA). Plasma samples ($100{\mu}l$) were added with chlorantraniliprole as an internal standard and then mixed with the 0.1% formic acid-containing extraction solution composed of isopropyl alcohol and ethyl acetate (1:4, v/v). After centrifugation, the supernatant was concentrated at $45^{\circ}C$ under negative pressure and centrifugal force. The residue was reconstituted with a mobile phase and injected into the HPLC instrument using a reverse phase Waters XTerra$^{TM}$ C18 column (particle size $3.5{\mu}m$). Liquid chromatography was carried out within the run time of 5 min using a mobile phase composed of buffer (0.1% formic acid and 10 mM ammonium formate), methanol, and acetonitrile (1:6:3, v/v/v). The analytes were monitored by tandem mass spectrometry in the multiple reaction monitoring method programmed to detect sorafenib at 'm/z 465.2 ${\rightarrow}$ 252.5' and chlorantraniliprole at 'm/z 484.4 ${\rightarrow}$ 286.2' with positive electrospray ionization mode ($ES^+$). The result showed the proper linearity ($r^2$ > 0.99) over the range of 2,000-5,000 ng/ml with good accuracy (90.7-103.9%) and precision (less than 10%). The newly developed method using LC/MS/MS was validated by the guideline of KFDA and identified as more sensitive compared to the previous methods.

• Food Engineering Progress
• /
• v.14 no.4
• /
• pp.307-315
• /
• 2010

The safety and security of food supply should be one of the primary responsibilities of any government. Estimation of nation's food commodity intakes is important to control the potential risks in food systems since food hazards are often associated with quality and safety of food commodities. The food intake databases provided by Korea National Health and Nutrition Examination Survey (KNHANES) are good resources to estimate the demographic data of intakes of various food commodities. A limitation of the KNHANES databases, however, is that the food intakes surveyed are not based on commodities but ingredients and their mixtures. In this study, reasonable calculation strategies were applied to convert the food intakes of the ingredients mixtures from the KNHANES into food commodity intakes. For example, Perilla leaf consumed with meat, raw fish, and etc. in Korean diets was used to estimate its Korean intakes and develop algorithms for demographic analysis. Koreans have consumed raw, blanched, steamed, and canned perilla leaf products. The average daily intakes of the perilla leaf were analyzed demographically, for examples, the intakes by gender, age, and etc. The average daily intakes of total perilla leaf were 2.03${\pm}$0.27 g in 1998, 2.11${\pm}$0.26 g in 2001, 2.29${\pm}$0.27 g in 2005, 2.75${\pm}$0.35 g in 2007, and 2.27${\pm}$0.20 g in 2008. Generally, people equal to or over 20 years of age have shown higher perilla leaf intakes than people below 20. This study would be contributed to the estimation of intakes of possible chemical contaminants such as residual pesticides and subsequent analysis for their potential risk.

• The Korean Journal of Pesticide Science
• /
• v.13 no.3
• /
• pp.148-158
• /
• 2009

We tested and selected some agrochemicals reducing the occurrence of major pests and diseases during garlic storage. Tebuconazole, diphenylamine and prochloraz as fungicides and dimethate as a insecticide were sprayed or drenched before harvest. And the harvested garlic was dipped in each of the agrochemicals. The residues of pesticides in garlic bulbs treated were analyzed every month from harvesting time for 6 months. In case of Danyang garlic, which was treated with pesticides before and after harvesting, the residues of diphenylamine, tebuconazole, prochloraz, and dimethoate ranged from 0.008 to 0.28, from 0.03 to 0.32, from 0.02 to 0.12, and from 0.02 to 0.25 mg/kg, respectively. In case of Uiseong garlic, the residues of diphenylamine, tebuconazole, prochloraz and dimethoate ranged from 0.008 to 0.09, from 0.08 to 0.45, from 0.02 to 0.57, and from 0.04 to 0.38 mg/kg, respectively. And, in case of Namdo garlic, the residues of diphenylamine, tebuconazole, prochloraz, and dimethoate ranged from 0.008 to 0.52, from 0.07 to 1.67, from 0.02 to 0.17, and from 0.03 to 0.73 mg/kg, respectively. Some of the garlic samples treated with tebuconazole exceeded its maximum residue limits (MRLs) of 0.1 mg/kg set by Korea Food Drug Administration (KFDA), but dimethoate was detected below its MRL of 1.0 mg/kg. In case of diphenylamine and prochloraz, their MRLs for garlic were not set. Adapting their MRLs, 5.0 mg/kg of diphenylamine for apple and pear and 0.5 mg/kg of prochloraz for strawberry and grape, residue levels of diphenylamine and procloraz were below than their MRLs, with the exception of samples two times treated with procloraz in Namdo garlic. These results indicate that dimethoate can be used as an agrochemical to control the postharvest disease in garlic in only MRL aspect.

• Analytical Science and Technology
• /
• v.13 no.4
• /
• pp.494-503
• /
• 2000

A 21-residue peptide corresponding to amino acids 84-104 of $p16^{INK4A}$, the tumor suppressor, has been synthesized and its structure was studied by Circular Dichroism, $^1H$ NMR spectroscopy and molecular modeling. A p16-derived peptide (84-104 amino acids) forming stable complex with CDK4 and CDK6 inhibits the ability of CDK4/6 to phosphorylate pRb in vitro, and blocks cell-cycle progression through G1/S phase as shown in the function of the full-length p16. Its NMR spectral data including NOEs, $^3J_{NH-H{\alpha}}$ coupling constants, $C_{\alpha}H$ chemical shift, the average amplitude of amide chemical shift oscillation and temperature coefficients indicate that the secondary structure of a p16-derived peptide is similar to that of the same region of full-length p16, which consists of helix-turn-helix structure. The 3-D distance geometry structure based on NOE-hased distance and torsion angle restraints is characterized by ${\gamma}$-turn conformation between residues $Gly^{89}-Leu^{91}$(${\varphi}_{i+1}=-79.8^{\circ}$, ${\varphi}_{i+1}=60.2^{\circ}$) as evidenced in a single crystal structure for the corresponding region of p18 or p19, but is undefined at both the N and C termini. This compact and rigid ${\gamma}$-turn region is considered to stabilize the structure of p16-derived peptide and serve as a site recognizing cyelin dependent kinase, and this well-defined ${\gamma}$-turn structure could be utilized for the design of anti-cancer drug candidates.

• Food Science and Preservation
• /
• v.22 no.2
• /
• pp.218-224
• /
• 2015

Crickets have been used as crude drug for treating fever and hypertension in East Asia. This study was carried out to investigate the quality characteristics such as the microbial and nutrient contents of crickets (Gryllus bimaculatus) prepared with various processing conditions for use as food. These conditions included the lyophilization process (LP), hot-air process (HP, $90^{\circ}C$ for 7 hr), roasting process (RP, $160^{\circ}C$ for 40 min), and frying process (FP, $180^{\circ}C$ for 30 sec). The total bacterial population of the crickets was 5~7 log CFU/g, but Coliform and E. coli were not detected. The major fatty acids in all the samples were palmitic acid (C16:0), oleic acid (C18:1), and linoleic acid (C18:2). The level of polyunsaturated fatty acids was highest (63.55 g/100 g) in the LP-processed crickets. As for the amino acid content, the glutamic acid level was highest in all the samples, and the RP and FP decreased by 12.01% and 53.88%, respectively, compared to that of the LP. The mineral contents were highest in the LP-processed crickets. Hg was detected at about 1.0 ppb in all the samples, but its level was lower than the residue tolerance level in the Korean Food Code. Such conditions should be considered to better understand the quality characteristics of crickets in food processing.

• Journal of Environmental Health Sciences
• /
• v.43 no.4
• /
• pp.257-266
• /
• 2017

Objectives: The hazardous metals content of medicinal herbs distributed in the Daegu area was investigated, and the place of origin and the content of herbicides and medicinal components were studied. Methods: An analysis of hazardous metals content (10 types) was carried out on 164 samples of 99 types of herbal medicines. Among the total samples, 45 were domestic and 119 were imported. Hg was analyzed by the amalgamation method. Other hazardous metals content (nine types) was digested using the microwave method and measured by inductively coupled plasma optical emission spectrometry (ICP-OES). Results: The mean values of the hazardous metals content in the herbal medicines were Pb 1.0833 mg/kg, As 0.0136 mg/kg, Cd 0.0840 mg/kg, Cr 3.7120 mg/kg, Cu 4.2666 mg/kg, Mn 40.080 mg/kg, Ni 1.4330 mg/kg, Sb 0.1053 mg/kg, Al 202.64 mg/kg and Hg 0.0062 mg/kg. Three of the samples violated the Ministry of Food and Drug Safety (MFDS) regulatory guidance on cadmium (less than 0.3 mg/kg). The measured values of heavy metals (Pb, As, Cd, Hg) showed levels below the recommended levels for herbal medicines in MFDS regulatory guidance. In the comparison of domestic samples with imported herbal medicines, it was found that one domestic and two imported samples surpassed the maximum residue limits for cadmium. The median values of the hazardous metals detected in the three medicinal parts of the root, leaf (branch), and flower (seed and fruit) were as follows. Cr, Ni, Sb and Al were highly detected in roots, Pb, Cd, Mn, Hg in leafs (branch), and As, Cu in flowers (seed and fruit). Conclusion: There were various kinds of hazardous metals which were detected at high levels according to the place of origin of the medicinal herb and the parts the plant. For hazardous metals for which no acceptance criteria have been established, safety standards should be further studied and managed to ensure the safety of herbal medicines.

• Journal of Applied Biological Chemistry
• /
• v.53 no.1
• /
• pp.25-30
• /
• 2010

This paper describes a simultaneous method for the determination of two aminoglycosides (neomycin and gentamicin) using solid phase extraction followed by liquid chromatograph-mass spectrometry. The extract was applied to an WCX and HLB solid phase extraction cartridge. The cartridges were washed with water and methanol, and analytes were eluted with TCA buffer-acetonitrile mixture. The aminoglycosides were separated by ion-pairing reversed phase mode prior to ESI-LC/MS. Under the conditions applied neomycin was almost separated from all the gentamicin compounds. No interfering peaks from endogenous compounds of matrix were noted at the elution position of the analytes. Recoveries of neomycin fortified at levels of 0.25, 0.5, 1.0 and 2.0 mg/kg seafood samples ranged from 92 to 115%. Recoveries of gentamycin fortified at levels of 0.05, 0.1, 0.2, 0.4 mg/kg seafood samples ranged from 99 to 116%. Method detection limits in four seafood sample matrices were between 0.002 and 0.033 mg/kg.