• Journal of Food Hygiene and Safety
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• v.30 no.3
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• pp.272-280
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• 2015

A simultaneous official method was developed for the determination of phorate and its metabolites (phorate sulfoxide, phorate sulfone, phorate oxon, phorate oxon sulfoxide, phorate oxon sulfone) in livestock samples. The analytes were quantified and confirmed via liquid chromatograph-tandem mass spectrometer (LC-MS/MS) in positive ion mode using multiple reaction monitoring (MRM). Phorate and its metabolites were extracted from beef and milk samples with acidified acetonitrile (containing 1% acetic acid) and partitioned with anhydrous magnesium sulfate. Then, the extract was purified through primary secondary amine (PSA) and C18 dispersive sorbent. Matrix matched calibration curves were linear over the calibration ranges (0.005-0.5 mg/L) for all the analytes into blank extract with $r^2$ > 0.996. For validation purposes, recovery studies were carried out at three different concentration levels (beef 0.004, 0.04 and 0.2 mg/kg; milk 0.008, 0.04 and 0.2 mg/kg, n = 5). The recoveries were within 79.2-113.9% with relative standard deviations (RSDs) less than 19.2% for all analytes. All values were consistent with the criteria ranges requested in the Codex guidelines. The limit of quantification was quite lower than the maximum residue limit (MRL) set by the Ministry of Food and Drug Safety (0.05 mg/kg). The proposed analytical method was accurate, effective and sensitive for phorate and its metabolites determination and it will be used to as an official analytical method in Korea.

• Journal of Food Hygiene and Safety
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• v.38 no.4
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• pp.217-227
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• 2023

The consumption of ready-to-eat side dishes is rapidly growing in South Korea. These foods are particularly vulnerable to microbiological contamination as they are often cooked without any treatment, such as heating or stored at room temperature after cooking. Hence, in 2022, we analyzed the ready-to-eat side dishes sold in Gyeongsangnam-do, South Korea for microbiological contamination. We collected 100 samples from supermarkets in 7 cities, and then examined them for presence of food-borne pathogens and sanitary indicator bacteria. In the analysis of the food-borne pathogens, Bacillus cereus and Clostridium perfringens were isolated from 51 samples (51.0%) and 3 samples (3.0%), respectively. However, both quantitatively met the Korean Food Standards Codex. Genes of five different enterotoxins and one emetic toxin were analyzed from the 51 isolated B. cereus strains. We detected enterotoxin entFM (100.0%), nheA (94.1%), hblC (58.8%), cytK (56.9%), and bceT (41.2%) in 51 isolates, and emetic toxin gene, CER, in only one (2.0%) isolate. We did not detect C. perfringens toxin gene (cpe) that causes food poisoning in any one of the three C. perfringens isolates. In the case of sanitary indicator bacteria, Kimchi had the highest levels of total aerobic bacteria and coliforms, followed by Saengchae, Jeotgal, Jeolim, Namul, and Jorim, respectively. We counted total aerobic bacteria at two different storage temperatures (4℃ and 20℃) to determine the effect of storage temperature. When stored at 20℃, total aerobic bacteria count increased in most of the ready-to-eat side dishes, except for Jeotgal. This result conclusively shows the need for refrigerating the ready-to-eat side dishes after purchase. Further research is needed to assess the risk and safety of the ready-to-eat side dishes available in the market and determine appropriate safety management practices.

• Journal of Food Hygiene and Safety
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• v.32 no.4
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• pp.290-297
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• 2017

The purpose of this study was developed for the determination of tridemorph in agricultural commodities samples. Tridemorph residues in samples were extracted with acetonitrile, partitioned with saline water, and then purified using and aminopropyl ($NH_2$) SPE catridge. The purified samples 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 (0.005~2.5 ng) into a blank extract with $r^2$ > 0.999. The limits of detection and quantification were 0.001 and 0.005 mg/kg, respectively. The average recovery ranged between 75.9% and 103.7% at different concentration levels (LOQ, 10 LOQ, 50 LOQ, n = 5) with relative standard deviations (RSDs) less than 9.0%. An interlaboratory study was conducted to validate the method by Korea Advanced Food Research Institute. The average recovery ranged between 87.0% and 109.2% at different concentration levels (LOQ, $10{\times}LOQ$, $50{\times}LOQ$, n = 5) with relative standard deviations (RSDs) less than 8.0%. All values were consistent with the criteria ranges requested in the Codex guidelines (CAC/GL40, 2003) and Food Safety Evaluation Department guidelines (2016). The results prove that the developed analytical methods is accurate, effective and sensitive for tridemorph determination.

• Journal of Food Hygiene and Safety
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• v.38 no.3
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• pp.79-88
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• 2023

Trifludimoxazin is a triazinone herbicide that inhibits the synthesis of protoporphyrinogen oxidase (PPO). The lack of PPO damages the cell membranes, leading to plant cell death. An official analytical method for the safety management of trifludimoxazin is necessary because it is a newly registered herbicide in Korea. Therefore, this study aimed to develop a residual analysis method to detect trifludimoxazin in five representative agricultural products. The EN method was established as the final extraction method by comparing the recovery test and matrix effect with those of the QuEChERS method. Various sorbent agents were used to establish the clean-up method, and no differences were observed among them. MgSO₄ and PSA were selected as the final clean-up conditions. We used LC-MS/MS considering the selectivity and sensitivity of the target pesticide and analyzed the samples in the MRM mode. The recovery test results using the established analysis method and inter-laboratory validation showed a valid range of 73.5-100.7%, with a relative standard deviation and coefficient of variation less than 12.6% and 14.5%, respectively. Therefore, the presence of trifludimoxazin can be analyzed using a modified QuEChERS method, which is widely available in Korea to ensure the safety of residual insecticides.

• 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.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.11
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• pp.1796-1800
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• 2014

Trienzyme digestion (AOAC Official Method 2004.05) procedure using protease, ${\alpha}$-amylase, and chicken pancreas conjugase was evaluated to determine its usefulness in the microbiological quantitation of total folate in foods. Folate values obtained by alkali hydrolysis (Korean Food Standards Codex) were compared to those obtained by the trienzyme method for four certified reference materials (CRM) representing diverse matrixes. Trienzyme treatment increased measurable folate from most CRM compared to levels found after alkali hydrolysis. The largest increases were observed with CRM 487 (pig liver, 5.8-fold) and CRM 121 (whole meal flour, 3.1-fold) after trienzyme digestion. Using trienzyme digestion method, total folate contents of raw and blanched edible plants were determined. Eleutherococcus senticosus ($146.9{\mu}g/100g$) showed the highest total folate content, followed by Aster glehni F. Schmidt ($142.8{\mu}g/100g$) and Ledebouriella seseloides H. Wolff ($140.4{\mu}g/100g$) on a wet weight basis. Blanching of samples resulted in an insignificant decrease in folate content for five samples and 11~63% reduction for nine samples. Our finding suggests that trienzyme digestion method is accurate for the determination of food folate in leafy vegetables.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.388-394
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• 2014

BACKGROUND: Aclonifen is used as a systemic and selective herbicide to control a wide spectrum broad-leaf weeds by inhibition carotenoid biosynthesis, and then its MRLs(Maximum Residue Limits) will be determined in onion and garlic. In this study, a new official method was developed for aclonifen determination in agricultural products to routinely inspect the violation of MRL as well as to evaluate the terminal residue level. METHODS AND RESULTS: Aclonifen was extracted from crop samples with acetone and the extract was partitioned with dichloromethane and then purified by silica solid phase extraction(SPE) cartridge. The purified samples were detected GC using an ECD detector. Limits of detection(LOD) was 0.001 mg/kg and quantification(LOQ) was 0.005 mg/kg, respectively. For validation purposes, recovery studies were carried out at three different concentration levels (LOQ, $10{\times}LOQ$, $50{\times}LOQ$, n=5). The recoveries were ranged from 74.3 to 95.0% with relative standard deviations(RSDs) of less than 8%. All values were consistent with the criteria ranges requested in the Codex guidelines(CAC/GL 40). CONCLUSION: The proposed analytical method was accurate, effective and sensitive for aclonifen determination and it will be used to as an official method in Korea.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.4
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• pp.550-560
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• 2012

This study was performed to investigate the physicochemical properties of sea urchin ($Anthocidaris$ $crassispina$, $Pseudocentrotus$ $depressus$, $Hernicentrotus$ $pulcherrimus$) roe as a processed or canned food by steaming treatment. Proximate compositions of $A.$ $crassispina$ roe and $P.$ $depressus$ roe were similar, but water, crude ash, and carbohydrate contents of $H.$ $pulcherrimus$ roe showed little differences. Proximate compositions of sea urchin roe showed slight differences with steaming time, raw samples showed no differences. Glycine content of the three raw sea urchin roe samples showed the highest concentration among free amino acids, followed by arginine, alanine, and lysine, in order. Total free amino acid contents of raw sea urchin roe were 754.70 mg% ($A.$ $crassispina$), 567.75 mg% ($P.$ $depressus$), and 449.44 mg% ($H.$ $pulcherrimus$). Total free amino acid content of 5 min steaming sample was highest among steaming and canning conditions. ATP, ADP, and AMP contents of raw $P.$ $depressus$ roe sample was higher than those of $A.$ $crassispina$and $H.$ $pulcherrimus$ roe. Major fatty acids of the three raw sea urchin roe samples were myristic acid, palmitic acid, and EPA. S.F.A. content of raw samples of $A.$ $crassispina$and $H.$ $pulcherrimus$ roe was higher than U.F.A content, whereas U.F.A. content of $P.$ $depressus$ roe was highest among the three raw samples. For minerals K, P, Fe, and Zn contents were highest in $A.$ $crassispina$roe while Ca, Mg, Na, and Cu contents were highest in $H.$ $pulcherrimus$ roe. For heavy metals, Cd, Pb and As were detected in all samples in trace amounts under the criteria of the Korea food codex.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.4
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• pp.517-524
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• 2009

We collected 177 fishes representing 53 species of fish from the eastern (Pohang), western (Gunsan), and southern (Tongyeong) coasts of Korea, and measured their heavy metal contents. The mean recoveries of the heavy metals extracted from cod muscle (certified reference material, CRM) were $88.7{\sim}100.6%$. The mean levels of the heavy metals in the samples taken from the edible portion of each fish were high in the order of Zn ($8.981{\pm}4.835{\mu}g/g$), Cu ($0.755{\pm}0.507{\mu}g/g$), and Mn ($0.433{\pm}0.699{\mu}g/g$), which are necessary metals in the human body, and then followed by Cr ($0.206{\pm}0.181{\mu}g/g$), Ni ($0.081{\pm}0.110{\mu}g/g$), Pb ($0.038{\pm}0.046{\mu}g/g$), Cd ($0.017{\pm}0.023{\mu}g/g$). The average daily intakes of the heavy metals by the fishes were as follows: Cd (0.81 ${\mu}g$), Cr (9.98 ${\mu}g$), Cu (36.63 ${\mu}g$), Mn (21.01 ${\mu}g$), Ni (3.93 ${\mu}g$), Pb (1.84 ${\mu}g$) and Zn (435.58 ${\mu}g$). The average weekly intakes of Cd, Cu, Pb and Zn by the fishes were 1.35%, 0.12%, 0.86%, and 0.73% respectively, as compared with PTWI (Provisional Tolerable Weekly Intakes) established by FAO/WHO Expert Committee for Food Safety Evaluation.

• Journal of Food Hygiene and Safety
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• v.29 no.2
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• pp.123-130
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• 2014

A simultaneous determination was developed for 9 aminoglycoside antibiotics (amikacin, apramycin, dihydrostreptomycin, gentamicin, hygromycin B, kanamycin, neomycin, spectinomycin, and streptomycin) in meat by liquid chromatography tandem mass spectrometry (LC-MS/MS). Each parameter was established by multiple reaction monitoring in positive ion mode. The developed method was validated for specificity, linearity, accuracy, and precision based on CODEX validation guideline. Linearity was over 0.98 with calibration curves of the mixed standards. Recovery of 9 aminoglycosides ranged on 60.5~114% for beef, 60.1~112% for pork and 63.8~131% for chicken. The limit of detection (LOD) and limit of quantification (LOQ) were 0.001~0.009 mg/kg and 0.006~0.03 mg/kg, respectively in livestock products including beef, pork and chicken. This study also performed survey of residual aminoglycoside antibiotics for 193 samples of beef, pork and chicken collected from 9 cities in Korea. Aminoglycosides were not found in any of the samples.