• Korean Journal of Food Science and Technology
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• v.45 no.5
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• pp.531-536
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• 2013

We developed a simple, sensitive, and specific analytical method for prometryn using gas chromatography-mass spectrometry (GC-MS). Prometryn is a selective herbicide used for the control of annual grasses and broadleaf weeds in cotton and celery crops. On the basis of high specificity, sensitivity, and reproducibility, combined with simple analytical operation, we propose that our newly developed method is suitable for use as a Ministry of Food and Drug Safety (MFDS, Korea) official method in the routine analysis of individual pesticide residues. Further, the method is applicable in clams. The separation condition for GC-MS was optimized by using a DB-5MS capillary column ($30m{\times}0.25mm$, 0.25 ${\mu}m$) with helium as the carrier gas, at a flow rate of 0.9 mL/min. We achieved high linearity over the concentration range 0.02-0.5 mg/L (correlation coefficient, $r^2$ >0.998). Our method is specific and sensitive, and has a quantitation limit of 0.04 mg/kg. The average recovery in clams ranged from 84.0% to 98.0%. The reproducibility of measurements expressed as the coefficient of variation (CV%) ranged from 3.0% to 7.1%. Our analytical procedure showed high accuracy and acceptable sensitivity regarding the analytical requirements for prometryn in fishery products. Finally, we successfully applied our method to the determination of residue levels in fishery products, and showed that none of the analyzed samples contained detectable amounts of residues.

• The Korean Journal of Pesticide Science
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• v.19 no.3
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• pp.161-173
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• 2015

The multiresidue method 4.1.2.2 in Korea Food Code was extended for the analysis of 24 unregistered pesticide residues. The method includes acetonitrile extraction, liquid-liquid partition, Florisil SPE clean-up and GC analysis. The limits of quantification (LOQ) range of the method was 0.02~0.05 mg/kg for orange, brown rice and banana. The linearity for targeted pesticides were $R^2$ > 0.99 at the level ranged from 0.05 to 5 mg/L. Recovery test was performed at two concentration levels of LOQ and 4~10 times of LOQ. Recoveries and relative standard deviations (RSDs) of target pesticides were acceptable, showing 70~120% range and less than 20%, respectively, except for ethiprole, picloram and sulcotrion. This method is effectively applicable to routine analysis of target pesticides in orange, brown rice and banana.

• Journal of Food Hygiene and Safety
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• v.33 no.4
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• pp.296-305
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• 2018

Spiroxamine, one of fungicides, is used to control powdery mildew in various crops and black yellow sigatoka in bananas. The major strength of spiroxamine is to control powdery mildew in various crops and bananas yellow sigatoka in bananas. The compound has shown a high level of activity, good persistence and crop tolerance. Besides powdery mildew, good control of rust, net blotch and Rhynchosporium diseases been indicated in cereals, together with a complementary activity against Septoria diseases. In 2017, the maximum residue limit (MRL) of spiroxamine established in Korea. According to Ministry of ood and rug afety) regulations, spiroxamine residues defined only parent compound. Thus, a analytical method is needed to estimate the residue level of the parent compound. The objective of this study was to develop and validate analytical method for spiroxamine in representative agricultural commodities. Samples were extracted with acetonitrile and partitioned with dichloromethane to remove the interfering substances. The analyte were quantified and confirmed liquid chromatograph-tandem mass spectrometer (LC-MS/MS) in positive-ion mode using multiple reaction monitoring (MRM). Matrix matched calibration curves were linear over the calibration ranges ($0.0005{\sim}0.1{\mu}g/mL$) for the analyte in blank extract with coefficient of determination ($r^2$) > 0.99. For validation purposes, recovery studies will be carried out at three different concentration levels (LOQ, 10LOQ, and 50LOQ) performing five replicates at each level. The recoveries 70.6~104.6% with relative standard deviations (RSDs) less than 10%. All values were consistent with the criteria ranges in the Codex guidelines (CAC/GL40, 2003) and MFDS guidelines. proposed analytical method be used as an official analytical method in the Republic of Korea.

• Analytical Science and Technology
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• v.29 no.2
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• pp.94-103
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• 2016

An analytical method was developed to determine the amount of spinetoram (spinetoram J and spinetoram L) in livestock samples. The spinetoram was extracted with acetonitrile and purified through a primary secondary amine (PSA) sorbent. The spinetoram residues were then quantified and confirmed using a liquid chromatography–tandem mass spectrometer (LC-MS/MS) in the positive ion mode using multiple reactions monitoring (MRM). Matrix-matched calibration curves were linear over the calibration ranges (0.005-0.5 mg/kg) into a blank extract with r² > 0.994. The limits of detection and quantification were 0.002 and 0.01 mg/kg, respectively. The recovery results of spinetram ranged between 81.9-106.4% at different concentration levels (LOQ, 10LOQ, 50LOQ, n=5) with relative standard deviations (RSDs) less than 10%. All values were consistent with the criteria ranges requested in the Codex guidelines (CAC/GL40, 2003). An interlaboratory study was conducted to validate the method. The proposed analytical method proved to be accurate, effective, and sensitive for spinetoram determination. The method will be used as an official analytical method in Korea.

• The Korean Journal of Pesticide Science
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• v.20 no.2
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• pp.93-103
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• 2016

A simultaneous analytical method was developed for the determination of isoxaflutole and metabolite (diketonitrile) in agricultural commodities. Samples were extracted with 0.1% acetic acid in water/acetonitrile (2/8, v/v) and partitioned with dichloromethane to remove the interference obtained from sample extracts, adjusting pH to 2 by 1 N hydrochloric acid. The analytes were quantified and confirmed via liquid chromatograph-tandem mass spectrometer (LC-MS/MS) in positive-ion mode using multiple reaction monitoring (MRM). Matrix matched calibration curves were linear over the calibration ranges ($0.02-2.0{\mu}g/mL$) for all the analytes into blank extract with $r^2$ > 0.997. For validation purposes, recovery studies were carried out at three different concentration levels (LOQ, 10LOQ, and 50LOQ) performing five replicates at each level. The recoveries were ranged between 72.9 to 107.3%, with relative standard deviations (RSDs) less than 10% for all analytes. All values were consistent with the criteria ranges requested in the Codex guideline (CAC/GL40, 2003). Furthermore, inter-laboratory study was conducted to validate the method. The proposed analytical method was accurate, effective, and sensitive for isoxaflutole and diketonitrile determination in agricultural commodities.

• The Korean Journal of Pesticide Science
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• v.16 no.3
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• pp.217-221
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• 2012

This study was carried out to evaluate residual characteristics of tolclofos-methyl in ginseng and elucidate the reason for its high detection rate from fresh ginseng selling at markets. Seeds of ginseng were sowed after seed dressing with tolclofos-methyl and after a year of growth, the young seedlings were transplanted to field. They were then harvested annually until three-years of growth and the pesticide residue was analyzed in them. LOD and LOQ of the pesticide were 0.001 and 0.003 mg/kg, respectively. Recovery test was carried out to validate the analytical method for tolclofos-methyl in ginseng. The ginseng seedlings were fortified with the test pesticide at the level of LOQ, ten times of LOQ and maximum residue concentration of tolclofos-methyl. Its recovery ranged from 77.37 to 100.16%. Residual concentration of tolclofos-methyl in ginseng seedlings just before transplanting and two-year-old ginseng were from 7.58 to 8.05 and from 6.46 to 6.79 mg/kg, respectively. In case of three-year-old ginseng, it was found to be from 4.18 to 4.35 mg/kg. As a result of annual pesticide residue analysis, concentration of the pesticide was found to decrease time-coursely in ginseng. This may be due to decomposition and increasing of fresh weight of the ginseng during the cultivation periods of three years.

• The Korean Journal of Pesticide Science
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• v.16 no.3
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• pp.202-208
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• 2012

A high-performance liquid chromatographic (HPLC) method was developed to determine residues of cyromazine, a triazine insecticide, in agricultural commodities. Cyromazine was extracted with 90% aqueous methanol from representative crops which comprised brown rice, oyster mushroom, oriental melon, watermelon, and Chinese cabbage. Following to evaporation of methanol in the extract, the aqueous concentrate was acidified to form the protonated cyromazine. Dichloromethane partition was then applied to remove nonpolar co-extractives in the aqueous phase. Strong cation-exchange chromatography using Dowex 50W-X4 resin was employed for final purification of the extract. Cyromazine was successfully separated on a Zorbax SB-Aq $C_{18}$ column showing high retention for polar compounds. Cyromazine was sensitively quantitated by ultraviolet absorption at 214 nm. Limit of quantitation (LOQ) of the method was 0.04 mg/kg irrespective of sample types. Each crops were fortified at 3 different concentrations of cyromazine for recovery test. Mean recoveries from samples fortified at LOQ~2.0 mg/kg in triplicate ranged 80.2~103.3% in five agricultural commodities. Relative standard deviations in recoveries were all less than 6%. A selected-ion monitoring LC/MS method with electrospray ionization in positive-ion mode was also provided to confirm the suspected residue. The proposed method was reproducible and sensitive enough to routinely determine and inspect the residue of cyromazine in agricultural commodities.

• 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 the Korean Society of Food Science and Nutrition
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• v.43 no.7
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• pp.1062-1067
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• 2014

In the present study, a new analytical method was devised for the simultaneous determination of soluble carbohydrates in soybean seeds using high performance liquid chromatography/evaporative light scattering detection (HPLC/ELSD). The limit of quantification (LOQ) for soybean soluble carbohydrates ranged from 5.6~7.6 mg/kg using the HPLC/ELSD method and from 16.2~33.9 mg/kg using the high performance liquid chromatography/refractive index detection (HPLC/RID) method. Therefore, the HPLC/ELSD method was more sensitive than HPLC/RID. The precision values for retention time and peak area of the HPLC/ELSD method were evaluated by inter-day (n=5) and intra-day (n=10) assays using a standard solution. All precision values (CV<2.5%) for soybean soluble carbohydrates were acceptable and fulfilled international acceptance criteria. All linear calibration curves were obtained with a correlation coefficient of $R^2$ >0.999. The contents of soluble carbohydrates for the "Shingikong" (yellow soybean) and "Cheongjakong 3" (black soybean) samples were analyzed using the HPLC/RID and HPLC/ELSD methods. The difference in carbohydrate contents between the two detection methods was significant. Carbohydrate contents in the HPLC/ELSD method were higher than those in the HPLC/RID method. Overall, the HPLC/ELSD method showed satisfactory resolution with a favorable LOQ and reproducibility. Therefore, these results indicate that the HPLC/ELSD method may be applied to determine the contents of soluble carbohydrates in soybean seeds and related food stuffs.

• The Korean Journal of Pesticide Science
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• v.19 no.1
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• pp.5-13
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• 2015

A chromatographic method for the determination of imazapyr, a non-selective herbicide, in agricultural commodities was developed to use safety control of pesticide residue on crops, and was fully validated as an official method for residue analysis. Agricultural commodities, mandarin (fruit), hulled rice (cereal grains), pepper (vegetables), potato (potatoes) and soybean (beans) were extracted with methanol and partitioned with dichloromethane to remove the interference obtained from sample extracts, adjusting pH to 2.5 by 4N hydrochloric acid. Finally, they were analyzed by high performance liquid chromatography coupled to UV detector (HPLC-UVD). The developed method had the linearity in the range of test concentrations with coefficients of determination ($r^2$) more than 0.99. Recovery studies were carried out at three concentration levels (LOQ, 10LOQ, and 50LOQ) performing five replicates at each level. Recoveries were ranged between 72.1 to 108.0%, with relative standard deviations less than 10%. A consistent recovery was determined according to the CODEX guidelines (CAC/GL40, 2003). Finally, LC/MS with selected ion monitoring was also applied to confirm the suspected residues of imazapyr in agricultural samples. This developed method for determination of imazapyr residues in agricultural commodities. can be used as an official method.