• Applied Biological Chemistry
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• v.20 no.2
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• pp.236-241
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• 1977

Analytical method of carbofuran (2,3-dihydro-2, 2-dimethyl-7-benzofuranyl methyl carbamate) residues and its persistence in rice seeds, rice seedlings, rice plants and soils were studied by gas-liquid chromatographic analysis using electron capture detector. 1. The effective column material for clean-up is Florisil (5% $H_2O$)+Alumina (4% $H_2O$)+absorbent mixture with rinsing the first 300l of eluants to remove impurities in the column materials. 2. The method of applying an gelatin encapsulated carbofuran to the root zone of rice plant is the longest persistence in its residues. 3. By seed treatment, no carbofuran residues were detected in rice seeds and seedlings. 4. The amounts of carbofuran residues in rice seedlings is in proportion to the soaking time of rice seedlings in carbofuran solution rather than the concentration of the chemical. 5. Applying carbofuran by root zone has the higher and the loger residual effect than broadcast. 6. Persistence of carbofuran in the high clay content soil is longer than in the low clay content soil. 7. No carbofuran residue was detected in rough rice at havesting time.

• The Korean Journal of Pesticide Science
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• v.15 no.4
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• pp.389-400
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• 2011

A high-performance liquid chromatographic (HPLC) method was developed to determine residues of phenothrin and silafluofen, known as synthetic pyrethroids, in agricultural commodities. Insecticide residues were extracted with acetone from representative samples of four crops which comprised rice, apple, pepper and cabbage. The extract was purified serially by liquid-liquid partition and Florisil column chromatography. For rice and pepper samples, acetonitrile/n-hexane partition was additionally adopted to remove nonpolar interferences. Reversed phase HPLC using an octadecylsilyl column was successfully applied to separate two phenothrin isomers and silafluofen from sample co-extractives. Intact parent compounds were sensitively detected by ultraviolet absorption at 226 nm. Recovery experiment at the quantitation limit validated that the proposed method could apparently determine phenothrin and silafluofen residues at 0.02 and 0.01 mg/kg, respectively. Mean recoveries of phenothrin and silafluofen from four crop samples fortified at three levels in triplicate were in the range of 82.4~109.8% and 83.7~109.8%, respectively. Relative standard deviations of the analytical method were all less than 10%, irrespective of crop types and spiking levels. A selected-ion monitoring (SIM) LC/mass spectrometry (MS) with electrospray ionization was provided to confirm the suspected residue of phenothrin, even though no sufficient ionization of silafluofen was obtained. Both phenothrin and silafluofen could be successfully confirmed by gas chromatography/MS SIM with electron impact at 70 eV. The proposed method is sensitive, repeatable and rapid enough to apply to officially routine inspection of agricultural products.

• Journal of Nutrition and Health
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• v.16 no.2
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• pp.107-114
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• 1983

There has been no specific test available for identifying the sesame oil among common edible oils. As the contents of sesamin and the ratio of sterols allowed the estimation for the genuine sesame oil, the author investigated to establish some instrumental methods for verification of genuine sesame oil and its distribution in the market. The sesame oil was saponified and the sesamin and sterols were isolated from the unsaponiable fraction by Florisil column chromatography. The individual components were determined by gas- chromatography and sesamin standard (purified sesamin) was obtained by silicagel column chromatography. The gas- chromatographic condition using Flame Ionization Detector supported on 10% OV-101 with di-(2-ethylhexyl) sebacate as an internal standard was suitable, and quantitation of sesamin and sterols, including campesterol, stigmasterol and ${\beta}-sitosterol$ was carried out. The results of this study showed that contents of sesamin in genuine sesame oil were 0.3-0.5% and the ratio of stigmasterol to compesterol was 0.3-0.6 and ${\beta}-sitosterol$ to campesterol 3.0-3.8. The 50 samples from the markets in Seoul were composed of 70% genuine sesame oil, and others were mixed with palm oil, rape seed oil and soybean oil.

• Journal of Nutrition and Health
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• v.13 no.4
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• pp.159-166
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• 1980

Methods for the determination of sterols in sesame oils were studied. The sesame oils were saponified and the sterols isolated from the unsaponifiable matter by Florisil column chromatography, and the individual components were determined by means of gas chromatography. Campesterol, ${\beta}-sitosterol$, stigmasterol were found in sesame oil including unknown Ⅰ and Ⅱ. The use of SE-30 gas chromatographic column allows the slow elution, duplication of peaks and relatively low reproducibility, therefore, 3% OV-17 was suitable for the sterol analysis. The result of this study showed that contents of sterols in sesame oil were campesterol 8.4%, stigmasterol 4.5%, ${\beta}-sitosterol$ 33.9% and others 53.0% involving 8.8% of unknown I and 44.3% of unknown Ⅱ. There has been no specific test available for identifying the sesame oil among common edible oils. But the ratio of sterols in sesame oils allowed the estimation of genuiness. The ratio of sterols vs. campesterol in genuine sesame oils were stigmasterol 0.3- 0.6, ${\beta}-sitosterol$ 3.0-3.8 and unknown Ⅱ 3.0, respectively. The 65 samples were composed of genuine sesame oil 40%, mixed rape seed oil 3%, cotton seed oil 1. 5% others were reused soybean oil or re-extracted oil.

• Korean Journal of Environmental Agriculture
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• v.29 no.3
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• pp.247-256
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• 2010

A high-performance liquid chromatographic (HPLC) method was developed to determine buprofezin residues in hulled rice and fruits. The buprofezin residue was extracted with acetone and the extract was stepwise purified by liquid-liquid partition and Florisil column chromatography. For rice samples, acetonitrile/n-hexane partition was additionally employed to remove nonpolar lipids. Reversed phase HPLC using an octadecylsilyl column was successfully applied to separate buprofezin from sample co-extractives, as detected by ultraviolet absorption at 250 nm. Recovery experiment at the limit of quantitation validated that the proposed method could evidently determine the buprofezin residue at the level of 0.02 mg/kg. Mean recoveries from hulled rice, apple, pear, and persimmon samples fortified at three tenfold levels were in the range of 80.8~85.2%, 89.1~98.4%, 88.8~95.7% and 90.8~96.2%, respectively. Relative standard deviations of the analytical method were all less than 5%, irrespective of sample types. A selected-ion monitoring LC/mass spectrometry with positive electrospray ionization was also provided to sensitively confirm the suspected residue.

• Korean Journal of Pharmacognosy
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• v.32 no.3 s.126
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• pp.200-211
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• 2001

This study was carried out to determine the 11 organochlorine, 7 organophosphorus residual pesticides in 251 crude drugs. These residual pesticides in herbal drugs were extracted with acetonitrile and the extracts were cleaned up via LC-florisil solid phase extraction column. The prepared samples were assayed for pesticide residues using GC-ECD, NPD with capillary column and identified by GC-MSD. Recoveries were $63.9{\sim}111.5%$ in the organochlorine pesticides and $69.8{\sim}92.4%$ in the organophosphorus pesticides, and detection limits were $0.001{\sim}0.65\;ppm$ in the organochlorine pesticides and $0.0009{\sim}0.0074\;ppm$ in the organophosphorus pesticides. Pesticide residues were detected in 9 cases.

• Korean Journal of Environmental Agriculture
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• v.30 no.4
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• pp.432-439
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• 2011

BACKGROUND: An official analytical method was developed to determine etofenprox residues in agricultural commodities using high-performance liquid chromatography (HPLC). METHODS AND RESULTS: The etofenprox residue was extracted with acetone from representative samples of five raw products which comprised rice grain, apple, mandarin, cabbage, and soybean. The extract was then serially purified by liquid-liquid partition and Florisil column chromatography. For rice and soybean samples, acetonitrile/n-hexane partition was additionally coupled to remove nonpolar lipids. Reversed phase HPLC using an octadecylsilyl column was successfully applied to separate etofenprox from co-extractives. Intact etofenprox was sensitively detected by ultraviolet absorption at 225 nm. Recovery experiment at the quantitation limit validated that the proposed method could apparently determine the etofenprox residue at 0.02 mg/kg. Mean recoveries from five crop samples fortified at three levels in triplicate were in the range of 93.6~106.4%. Relative standard deviations of the analytical method were all less than 10%, irrespective of crop types. A selected-ion monitoring LC/mass spectrometry with positive atmospheric-pressure chemical ionization was also provided to confirm the suspected residue. CONCLUSION(s): The proposed method is simple, rapid and sensitive enough to be employed in routine inspection or monitoring of agricultural products for the etofenprox residue.

• Toxicological Research
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• v.25 no.1
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• pp.41-45
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• 2009

This study was conducted to monitor the level of bifenthrin residues in pear sprayed with 2% bifenthrin wettable powder (WP) at the recommended rate at four different schedules prior to harvest. The target analyte was extracted with acetone, partitioned into dichloromethane, and then purified by florisil chromatographic column. The residue determination was performed on a DB-5 capillary column using GC with electron capture detector (ECD). Linearity of this method was quite good ($r^2$ = 0.9951) in the concentration ranged from 0.2 mg/kg to 10 mg/kg. Recovery test was carried out at two concentration levels, 0.2 mg/kg and 1.0 mg/kg, in three replicates, and their rates were from 82.9% to 107.2%. No quantitative bifenthrin was detected in pear of all kinds of treatments including the treatment sprayed 4 times until 7 days before harvest. This sensitive and selective method can be used to monitor the trace residual amounts of bifenthrin in pear in a quite low concentration level.

• Journal of the Korean Chemical Society
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• v.29 no.5
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• pp.503-509
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• 1985

Sixteen organochlorine pesticides extracted out from the crops and cleaned by solvent-solvent partitioning and Florisil column chromatography were determined by gas-liquid chromatography. The majority of the pesticides were well separated by being eluted through 5% QF-1 column and some of them through 3% OV-17 column and 2.596 DC-200/2.5% QF-1 column, and the eluted pesticides were detected by $^{63}Ni$ electron capture detector. The linear calibration curves were obtained for the most of pesticides while some curves were slightly deviated from the linearity. In the determination of 16 pesticides added to thirteen kinds of crops, the recoveries were showed over 85% for the most cases and the relative standard deviations of 5 analyses were less than 12.1%. The results were within the criteria of the AOAC method.

• Analytical Science and Technology
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• v.13 no.5
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• pp.666-674
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• 2000

The present study describes an analytical method for the determination of polybrominated biphenyls (PBBs) in biota samples by gas chromatography-mass spectrometry (GC/MS). PBBs are extracted twice from 20 g samples with mixture solvent 40mL acetone and 80mL hexane using ultrasonic agitation for 20 min. Lipids in extracts are degraded by concentrated sulfuric acid and then PBBs are purified with Florisil column. The purified extracts are analyzed by GC/MS-selected ion monitoring mode for the quantitation of PBBs in biota sample. The overall recovery yields of PBBs range between 77 and 111% under these experimental conditions.