• Environmental Analysis Health and Toxicology
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• v.16 no.4
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• pp.181-188
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• 2001

A gas chromatographic method was established for the simultaneous determination of urinary nicotine and cotinine. The analytes in basified urine containing a sufficient amount of Na$_2$S0$_4$were extracted into dichloromethane by vigorous shaking. Into the transferred organic phase was added a small amount of acidified methanol (0.5 N HCI in methanol), followed by concentrating the mixture to dryness using a mild stream of nitrogen gas. The concentrate was reconstituted with methanol and the final solution analyzed using the gas chromatograph equipped with the nitrogen-phosphorus detector. The reproducibility tests showed coefficients of variation less than 11％ for both compounds. The percent recovery for both analytes ranged from 88 to 103％. The estimated method detection limits for nicotine and cotinine were 0.60 and 5.1 ng/mL, respectively. Extraction efficiencies for both nicotine and cotinine apparently declined without the addition of Na$_2$S0$_4$into the urine. Moreover, the absence of methanolic HCI in the extract resulted in almost complete evaporation of nicotine and partial loss of cotinine during the concentration process, indicating that the formation of nicotine-HCI and cotinine-HCI species is prerequisite to the suppression of the loss of both compounds.

• Analytical Science and Technology
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• v.21 no.2
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• pp.84-92
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• 2008

A method for the determination of trace amount of caffeine in urine and various drink samples using hollow fiber-liquid phase microextraction (HF-LPME) and capillary gas chromatograph/nitrogen phosphorus detector (GC/NPD) has been established. HF-LPME method has been optimized with respect to several experimental parameters including the effects of the hollow fiber length, extraction solvent, stirring mode, pH and salt concentration for the determination of caffeine from aqueous samples. The correlation coefficient of calibration curve for caffeine was 0.9994. The average recovery was 102%(n=3). The established method is feasible for the determination of trace amounts of caffeine in several aqueous sample. The limit of detection (LOD) and the limit of quantitation (LOQ) have been found to be 2.5 and 10 ng/mL, respectively. The established HF-LPME method for the analysis of caffeine from aqueous sample can be used for the determination of biological, food and environmental samples.

• Journal of Food Hygiene and Safety
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• v.20 no.3
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• pp.159-164
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• 2005

This method was described for the simultaneous determination of simetryn and buprofezin in rice, vegetables, and fruits by gas chromatography(GC) with nitrogen phosphorus detector. The GC method of simetryn and buprofezin was shown to give a linear detection ranges between $0.019\sim9.306mg/kg,\;0.023\sim11.27mg/kg$, respectively. For evaluation of GC method, simetryn spiked into rice, vegetables and fruits at the level of 4.653mg/kg was determined. The recoveries of simetryn by GC method were ranged from 57.9 to $115.9\%$. For evaluation of GC method, buprofezin spiked into rice, vegetables and fruits at the level of 2.817mg/kg was determined. The recoveries of buprofezin by GC method were ranged from 56.5 to $121.5\%.$

• The Korean Journal of Pesticide Science
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• v.16 no.3
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• pp.195-201
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• 2012

We tested for pesticide residues in 124 samples of 22 different items of imported fruits circulated in Gyeonggido. Total 218 pesticides were analyzed by multi-residue method using gas chromatography/nitrogen phosphorus detector-electron capture detector (GC/NPD-ECD), time of flight/mass spectrometer (TOF/MS), ultra performance liquid chromatography/photo diode array (UPLC/PDA), high performance liquid chromatography/fluorescence detector (HPLC/FLD) and mass spectrometer (LC/MS/MS). The pesticides were detected in 18 fruits samples, ranging 0.003~0.3 mg/kg and no samples had violative residue. The separation test to 14 sample pesticides detected was conducted to monitor the current status of pesticide residues according to the partial characteristic. The pesticides were detected in 14 peels ranging 0.03~1.5 mg/kg and 2 fleshes in less than detection limits. These results indicate that imported fruits are safe when the human takes normally but even the small amount of pesticides is harmful when the human takes it in a prolonged period. Therefore, the pesticide residual amounts of imported friuts should be constantly monitored for food safety.

• Korean Journal of Food Science and Technology
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• v.44 no.3
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• pp.378-381
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• 2012

The monitoring of the uniconazole residual pesticide for agricultural products was conducted by multiclass pesticide multiresidue methods. Samples were collected from June to November, 2011. Uniconazole pesticide was detected in 49 samples from a total of 3,939 samples. The amount of uniconazole pesticide ranged from 0.09 to 17.89 mg/kg in 49 samples. This method was described for the simultaneous determination of uniconazole by gas chromatography with a nitrogen phosphorus detector (GC-NPD) and mass spectrometry (MS). The limit of detection and quantification were 0.006 and 0.018 mg/kg GC-NPD, respectively. For an evaluation of the GC-NPD method, uniconazole spiked into gyeojachae at a level of 0.5, 5 mg/kg was determined. The recoveries of uniconazole by the GC-NPD method ranged from 83.4 to 101.4%. The results indicate that the method of simultaneous analysis is applicable to uniconazole analysis.

• The Korean Journal of Pesticide Science
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• v.14 no.4
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• pp.361-370
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• 2010

Considering the efficiencies of the preparation process at each stage obtained in previous studies, the analytical determination method was established for multi-pesticide residues in soils. It consist of the acetone-extraction, the dichloromethane-partition, the Florisil or silica-gel chromatography and the gas chromatography analysis equipped with the electron capture detector and the nitrogen-phosphorus detector. In the soil recovery test by Florisil clean-up system, the number of pesticides recovered in the range of 70~120% and showed less than 20% of RSD were 165 pesticides for paddy soil, 169 pesticides for upland soil and 159 pesticides in both soils through the tested 183 pesticides. And in the soil recovery test by silica-gel system, the number of pesticides recovered in the range of 70~120% and showed less than 20% of RSD were 154 pesticides for paddy soil, 145 pesticides for upland soil, and 134 pesticides in both soils.

• Journal of Environmental Science International
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• v.15 no.1
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• pp.85-94
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• 2006

The simultaneous analysis of multi-residual pesticides was developed using a gas chromatography (GC) method. In this study, a simple and reliable methodology was improved to detect 154 kinds of pesticides in sinseng extract sample by using a liquid-liquid extraction procedure, open column chromagraphy and chromatographic analysis by CC electron capture detector (ECD) and GC nitrogen-phosphorus detector (NPD). The 154 kinds of pesticides were classified in 4 groups according to the chemical structure. The extraction of pesticides was experimented with $70\%$ acetone and dichloromethane/petroleum ether in order, and cleaned up via open column chromatography $(3\times30cm)$ packed with florisil $(30g,\;130^{\circ}C,\;12hrs)$. The final extract was concentrated in a rotator evaporator at $40^{\circ}C$ until dryness. Then the residue was redissolved to 2ml with acetone, and analyzed by GC-ECD and GC-NPD. The applied concentration of pesticides was over $1\~10{\mu}g/ml$. The recovery tests were ranged from $70.7\%$ to $115.2\%$ with standard deviations between 0.3 and $5.7\%$ of the standard spiked to the ginseng extract sample (Group $I\~IV$). The limit of detection (LOD) ranged from 0.001 to $0.099{\mu}g/ml$ (Group $I\~IV$). The 9 kinds of pesticides were not detected. The developed method was applied satisfactory to the determination of the 154 kinds of pesticides in the ginseng extract with good reproducibility and accuracy.

• Fisheries and Aquatic Sciences
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• v.4 no.4
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• pp.201-207
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• 2001

To study the distribution of organophosphorus pesticides which are extensively used for agriculture in Korea. Sea water samples were taken from 4 coastal areas during May and August of 1997 and sediment samples were collected from two coastal areas in August of 1997. These samples were analyzed using a Gas Chromatography/Nitrogen Phosphorus Detector (GC/NPD). In August the most commonly found organophosphorus pesticides in the surface waters of Kunsan area were IBP < S-Benzyl O,O-di-isopropyl phosphorothioate > $(m=432.5ng\;L^{-1})$ and EDDP < O-ethyl S,S-diphenyl phosphorodithioate > $(m=37.4ng\;L^{-1}) $ which are largely used between June and September to prevent rice blast disease. In Danghang Bay, dry fields located near the mouth of the estuary seemed to affect the concentrations of certain organophosphorus pesticides in the surface waters. Since organophosphorus pesticides applied in the watershed are rapidly decomposed while being transported along freshwater streams, watershed size is not proportional to the concentrations of these pesticides in the coastal waters. Pesticides concentrations measured in August were compared with those in May. IBP concentrations in coastal waters were about an order of magnitude higher in August than in May. Temporal and geographical distribution of individual organophosphorus pesticides is likely to be affected by types of agricultural practices in the watershed. Chloropyrifos was the most important of the organophosphorus pesticides in the sediments of the study area because of its persistent nature and high affinity to particulates.

• Journal of the Korean Society for Marine Environment & Energy
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• v.5 no.1
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• pp.38-50
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• 2002

To study the distribution of organophosphorus pesticides which are extensively used for agriculture in Korea. Surface sea water samples were taken from 2 coastal areas during July and :;eptember of 1999 and sediment samples were collected from Kyeonggi bay in July of 1999. These samples were analyzed using a Gas Chromatography/Nitrogen Phosphorus Detector(GC/NPD). In coastal waters of the study areas IBP was commonly found the most compound. Traces of Diazinon, DDVP, Ethoprouhos and Chlorpyrifos were also encountered. Concentration of the other major organophosphorus pesticides(Disulfoton, Parathion Methyl, Fenchlorfos, Prothiofos, EDDP) were generally be below the detection limit of the employed analytical method. Tn sediment of the study areas Chlorpyrifos w3s found the most compound. Temporal and geographical distribution of individual organophosphorus pesticides is likely to be affected by types of agricultural practices in the watershed.

• Korean Journal of Environmental Agriculture
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• v.33 no.2
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• pp.111-120
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• 2014

BACKGROUND: This study was conducted to investigate the levels of pesticide residues in fruits and to assess their risk to human health. METHODS AND RESULTS: Monitoring of 215 samples of fruits collected from local markets in incheon during 2013 was performed. 259 pesticides were analyzed by multi-residue method and Quick, Easy, Cheap, Effective, Rugged, and safe/Mass/Mass(QuEChERS/MS/MS) method using Gas Chromatography-Electron Capture Detector/Nitrogen Phosphorus Detector(GC-ECD/NPD), GC-MS, LC(Liquid Chromatography-Mass/Mass(LC-MS/MS) and High Performance Liquid Chromatography-Photodiode Array/Fluorescence Detector(HPLC-PDA/FLD). In 56.3% of the samples detected pesticide residues and were not found to exceed Maximum Residue Limits(MRL). The highest detected samples were found in citrus fruits(83.9%). Among the detected compounds, carbendazim(13.1%), imazalil (11.7%), thiabendazole(10.7%) and fludioxonil(9.8%) were frequently found in fruits. A risk assessment of pesticide residues in fruits was performed by calculating Estimated Daily Intake(EDI) and Acceptable Daily Intake(ADI). Also, we were evaluated removal efficiency of pesticide residues by washing and peeling. The removal efficiency of pesticide residues in citrus and tropical fruits by peeling processes were 91.6%. After the washing process, the removal rates were 43.1%(Cherry, Grape, Blueberry). CONCLUSION: The level of pesticide residues in fruits was within the MRL. The range of %ADI values was from 0.00011 to 0.98795%. The process of washing or peeling reduces the level of pesticide residues. The results of this research concluded that the detected pesticides are not harmful to human being.