• Analytical Science and Technology
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• v.20 no.5
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• pp.383-392
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• 2007

The water soluble components were analyzed in the $PM_{2.5}$ fine particles collected at the 1100 site of Mt. Halla for the spring seasons between 1998 and 2004. The $PM_{2.5}$ mass concentrations were within $13.4{\pm}9.6{\sim}21.7{\pm}20.0{\mu}g/m^3$, and the concentrations of ionic components were in the order of nss-$SO{_4}^{2-}$ > $NH{_4}{^+}$ > $NO{_3}{^-}$ > $Ca^{2+}$ > $K^+$ > $Na^+$ > $Cl^-$ > $Mg^{2+}$, in which the concentration of nss-$SO{_4}^{2-}$($3.41{\pm}2.42{\mu}g/m^3$) was the highest. The concentrations of $NH{_4}{^+}$, $SO{_4}^{2-}$, and $NO{_3}{^-}$, the secondary pollutants, were respectively 0.60~1.50, 2.86~4.42, and $0.24{\sim}1.57{\mu}g/m^3$, which had occupied 88 % of the total ionic components, on the other hand, the concentrations of marine species were less than 5 %. The nss-$SO{_4}^{2-}$ showed the high correlation with $NH{_4}{^+}$, $K^+$, so that $NH{_4}{^+}$ and nss-$SO{_4}^{2-}$ might exist in the form of $(NH_4)_3H(SO_4)_2$ and $(NH_4)_2SO_4$ in fine particles. From the backward trajectory analysis, in case of high concentrations of $NH{_4}{^+}$ and nss-$SO{_4}^{2-}$ simultaneously, the air masses were originated and stagnated at the east region of China for a while, then moved into the atmosphere of Jeju. However, in case of $NO{_3}{^-}$ and nss-$Ca^{2+}$, the air masses originated at China and Siberia were moved into Jeju via the eastern China.

• Korean Journal of Ecology and Environment
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• v.56 no.4
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• pp.281-302
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• 2023

Carbon is not only an essential element for life but also a key player in climate change. The radiocarbon (¹⁴C) analysis using accelerator mass spectrometry (AMS) is a powerful tool not only to understand the carbon cycle but also to track pollutants derived from fossil carbon, which have a distinct radiocarbon isotope ratio (Δ¹⁴C). Many studies have reported Δ¹⁴C of carbon compounds in streams, rivers, rain, snow, throughfall, fine particulate matter (PM_2.5), and wastewater treatment plant effluents in South Korea, which are reviewed in this manuscript. In summary, (1) stream and river carbon in South Korea are largely derived from the chemical weathering of soils and rocks, and organic compounds in plants and soils, strongly influenced by precipitation, wastewater treatment effluents, agricultural land use, soil water, and groundwater. (2) Unprecedentedly high Δ¹⁴C of precipitation during winter has been reported, which can directly and indirectly influence stream and river carbon. Although we cannot exclude the possibility of local contamination sources of high Δ¹⁴C, the results suggest that stream dissolved organic carbon could be older than previously thought, warranting future studies. (3) The ¹⁴C analysis has also been applied to quantify the sources of forest throughfall and PM_2.5, providing new insights. The ¹⁴C data on a variety of ecosystems will be valuable not only to track the pollutants derived from fossil carbon but also to improve our understanding of climate change and provide solutions.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.3
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• pp.134-144
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• 2009

Paleoproductivity changes in the central part of the Bering Sea since the last glacial period were reconstructed by analyzing opal and total organic carbon (TOC) content and their mass accumulation rate (MAR) in sediment core PC23A. Ages of the sediment were determined by both AMS $^{14}C$ dates using planktonic foraminifera and Last Appearance Datum of radiolaria (L. nipponica sakaii). The core-bottom age was calculated to reach back to 61,000 yr BP. and some of core-top was missing. Opal and TOC contents during the last glacial period varied in a range of 1-10% and 0.2-1.0%, and their average values are 5% and 0.7%, respectively. In contrast, during the last deglaciation, opal and TOC contents varied from 5 to 22% and from 0.8 to 1.2%, respectively, with increasing average values of 8% and 1.0%. Opal and TOC MAR were low ($1gcm^{-2}kyr^{-1}$, $0.2gcm^{-2}kyr^{-1}$) during the last glacial period, but they increased (>5 and >$1gcm^{-2}kyr^{-1}$) during the last deglaciation. High diatom productivity during the last deglaciation was most likely attributed to the elevated nutrient supply to the sea surface resulting from increased melt water input from the nearby land and enhanced Alaskan Stream injection from the south under the restricted sea-ice and warm condition during the rising sea level. On the contrary, low productivity during the last glacial period was mainly due to decreased Alaskan Stream injection during the low sea-level condition as well as to extensive development of sea ice under low-temperature seawater and cold environment.

• Korean Journal of Environmental Agriculture
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• v.13 no.3
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• pp.321-337
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• 1994

The garbage from the dwelling houses was composted in two kinds of small composter in laboratory to investigate the possibility of garbage composting. They were general small composters. One (type 1) was insullated but the other (type 2) was not. Because it was found that type 2 was not available for composting under our meteorological conditions through winter experiment, only type 1 was tested in spring and summer. The experiment was performed for 8 weeks in each season. The seasonal variation of several compounds in compost was evaluated and discussed. The result summarized belows are those taken at the end of the experiment, if the time was not specified. 1) The maximum temperature was $58^{\circ}C$ in spring, $57^{\circ}C$ in summer and $41^{\circ}C$ in winter. This temperature was enough to destroy the pathogen except for winter. 2) The mass was reduced to average 62.5% and the volume reduction was avergae 74%. 3) The density was estimated as 0.7kg/l in spring, 0.8kg/l in summer and 1.1kg/l in winter. 4) The water content was not much changed for composting periods. It had 75.6% in spring and 76.6% in summer and winter. 5) There was a great seasonal difference in pH value. It was reached to pH 6.13 in spring, pH 8.62 in summer and pH 4.75 in winter. 6) The faster organic matter was decomposed, the greater ash content was increased. Cellulose and lignin content were increased, but hemicellulose content was reduced during composting period. 7) Nitrogen contents were in the range of 3.1-5.6% and especially high in summer. After ammonium nitrogen contents were increased at the early stage of composting period, they were decreased. The maximum ammonium nitrogen content was 3,243mg/kg after 2 weeks in winter, 6,053mg/kg after 3 weeks in spring and 30,828mg/kg after 6 weeks in summer. C/N-ratios were not much changed. Nitrification occurred actively in spring and summer. 8) The contents of volatile and higher fatty acids were increased in early stage of composting and reduced after that. The maximum content of total fatty acid was 10.1% after 2 weeks in winter, 5.8% after 2 weeks in spring and 15.7% after 4 weeks in summer. 9) The contents of inorganic compounds were not accumulated as composting was proceeded. They were in the range of 0.9-4.4% $P_2O_5$, 1.6-2.9% $K_2O$, 2.4-4.6% CaO and 0.30-0.80% MgO. 10) CN and heavy metal contents did not show any tendency. They were in the range of 0.11-28.99mg/kg CN, 24-166mg/kg Zn, 5-129mg/kg Cu, 0.8-14.3mg/kg Cd, 7-42mg/kg Pb, ND-30mg/kg Cr and $ND-132.16\;{\mu}g/kg$ Hg.

• The Korean Journal of Nuclear Medicine Technology
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• v.22 no.1
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• pp.67-75
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• 2018

Purpose The purpose of this study is to investigate and analyze the external dose rates of $^{18}F-FDG$ Whole Body PET/CT patients by distance, and to identify the main factors that contribute to the reduction of radiation dose by checking the cumulative doses of nuclear medicine technologist(NMT). Materials and Methods After completion of the $^{18}F-FDG$ Whole Body PET/CT scan($75.4{\pm}3.3min$), the external dose rates of 106 patients were measured at a distance of 0, 10, 30, 50, and 100 cm from the chest. Gender, age, BMI(Body Mass Index), fasting time, diabetes mellitus, radiopharmaceutical injection information, creatine value were collected to analyze individual factors that could affect external dose rates from a patient's perspective. From the perspective of NMT, personal pocket dosimeters were worn on the chest to record accumulated dose of NMT who performed the injection task($T_1$, $T_2$ and $T_3$) and scan task($T_4$, $T_5$ and $T_6$). In addition, patient contact time with NMT was measured and analyzed. Results External dose rates from the patient for each distance were calculated as $246.9{\pm}37.6$, $129.9{\pm}16.7$, $61.2{\pm}9.1$, $34.4{\pm}5.9$, and $13.1{\pm}2.4{\mu}Sv/hr$ respectively. On the patient's aspect, there was a significant difference in the proximity of gender, BMI, Injection dose and creatine value, but the difference decreased as the distance increased. In case of dialysis patient, external dose rates for each distance were exceptionally higher than other patients. On the NMT aspect, the doses received from patients were 0.70, 1.09, $0.55{\mu}Sv/person$ for performing the injection task($T_1$, $T_2$, and $T_3$), and were 1.25, 0.82, $1.23{\mu}Sv/person$ for performing the scan task($T_4$, $T_5$, $T_6$). Conclusion we found that maintaining proper distance with patient and reducing contact time with patient had a significant effect on accumulated doses. Considering those points, efforts such as sufficient water intake and encourage of urination, maintaining the proper distance between the NMT and the patient(at least 100 cm), and reducing the contact time should be done for reducing dose rates not only patient but also NMT.

• Korean Journal of Environmental Agriculture
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• v.14 no.2
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• pp.232-245
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• 1995

The garbage from the dwelling house was composted in two kinds of small composter in the laboratory, and the possibility of garbage composting was examined. The composters were general small. One (type 3) was constructed with the double layer walls and the other (type 4) was the same as the first except for being insulated. Because it was found that type 3 was not available for composting under our meteorological conditions through the winter experiment, only type 4 was tested in spring and summer. The experiment was performed for 8 weeks in each season. The seasonal variation of several components in the compost was evaluated and discussed. The results summarized below were those obtained at the end of the experiment, if the time was not specified. 1) The maximum temperature was $43^{\circ}C$ in winter, $55^{\circ}C$ in spring and $56^{\circ}C$ in summer. 2) The mass was reduced to an average of 63% and the volume reduction was an average of 78%. 3) The density was estimated as 1.5 kg/l in winter and 0.8 kg/l in spring and summer. 4) The water content was not much changed during the composting periods. It was 79.3% in winter, 75.0% in spring and 70.0% in summer. 5) After pH value increased during the first week, it decreased until the second week and increased again continuously thereafter. It reached pH 6.19 in winter, pH 7.59 in spring and pH 8.69 in summer. 6) The faster the organic matter was decomposed, the greater the ash content increased. The contents of cellulose and lignin increased, but that of hemicellulose decreased during the composting period. 7) Nitrogen contents were in the range of 3.3-6.8% and especially high in summer. After ammonium contents increased at the early stage of the composting period, they decreased. The maximum ammonium-nitrogen content was 2,404mg/kg after 8 weeks in winter, 12,400mg/kg after 3 weeks in spring and 20,718mg/kg after 3 weeks in summer. C/N-ratios decreased with the lapse of composting time, but they were not much changed. Nitrification occurred actively in summer. 8) The contents of volatile and higher fatty acids increased at the early stage of composting and reduced after that. The maximum content of total fatty acid was 9.7% after 6 weeks in winter, 14.8% after 6 weeks in spring and 15.8% after 2 weeks in summer. 9) The contents of inorganic components were not accumulated as composting proceeded. They were in the range of 0.9-4.4% $P_2O_5$, 1.6-2.4% $K_2O$, 2.2-5.4% CaO and 0.30-0.61% MgO. 10) CN and heavy metal contents did not show any tendency. They were in the range of 0.21-14.55mg/kg CN, 11-166mg/kg Zn, 5-65mg/kg Cu, 0.5-10.8mg/kg Cd, 6- 35mg/kg Pb, ND-33 mg/kg Cr and ND-302.04 g/kg Hg.

• Journal of Nutrition and Health
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• v.8 no.1
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• pp.15-37
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• 1975

I. Subject of the study A study on the nutritive value and utilization of powdered seaweeds. II. Purpose and Importance of the study A. In Korea the shortage of food will be inevitable by the rapidly growing population. It will be very important study to develop a new food from the seaweeds which were not used hitherto for human consumption. B. The several kinds of seaweeds have been used by man in Korea mainly as side-dishes. However, a properly powdered seaweed will enable itself to be a good supplement or mixture to certain cereal flours. C. By adding the powdered seaweed to any cereals which have long been staple foods in this country the two fold benefits; saving of cereals and change of dietary pattern, will be secured. III. Objects and scope of the study A. Objects of the study The objects will come under four items. 1. To develop a powdered seaweed as a new food from the seaweeds which have been not used for human consumption. 2. To evaluate the nutritional quality of the products the analysis for chemical composition and animal feeding experiment will be conducted. 3. Experimental cocking and accepability test will be conducted for the powdered products to evaluate the value as food stuff. 4. Sanitary test and also economical analysis will be conducted for the powdered products. B. Scope of the study 1. Production of seaweed powders Sargassum fulvellum growing in eastern coast and Sargassum patens C.A. in southern coast were used as the material for the powders. These algae, which have been not used for human consumption, were pulverized through the processes of washing, drying, pulverization, etc. 2. Nutritional experiments a. Chemical composition Proximate components (water, protein, fat, cellulose, sugar, ash, salt), minerals (calcium, phosphorus, iron, iodine), vitamins (A, $B_1,\;B_2$ niacin, C) and amino acids were analyzed for the seaweed powders. b. Animal feeding experiment Weaning 160 rats (80 male and 80 female rats) were used as experimental animals, dividing them into 16 groups, 10 rats each group. Each group was fed for 12 weeks on cereal diet (Wheat flour, rice powder, barley powder, potato powder, corn flour) with the supplementary levels of 5%, 10%, 15%, 20% and 30% of the seaweed powder. After the feeding the growth, feed efficiency ratio, protain efficiency ratio and ,organs weights were checked and urine analysis, feces analysis and serum analysis were also conducted. 3. Experimental cooking and acceptability test a. Several basic studies were conducted to find the characteristics of the seaweed powder. b. 17 kinds of Korean dishes and 9 kinds of foreign dishes were prepared with cereal flours (wheat, rice, barley, potato, corn) with the supplementary levels of 5%, 10%, 15%, 20% and 30% of the seaweed powder. c. Acceptability test for the dishes was conducted according to plank's Form. 4. Sanitary test The heavy metals (Cd, Pb, As, Hg) in the seaweed powders were determined. 5. Economical analysis The retail price of the seaweed powder was compared with those of other cereals in the market. And also economical analysis was made from the nutritional point of view, calculating the body weight gained in grams per unit price of each feeding diet. IV. Results of the study and the suggestion for application A. Chemical composition 1. There is no any big difference in proximate components between powders of Sargassum fulvellum in eastern coast and Sargassum patens C.A. in southern coast. Seasonal difference is also not significant. Higher levels of protein, cellulose, ash and salt were found in the powders compared with common cereal foods. 2. The levels of calcium (Ca) and iron (Fe) in the powders were significantly higher than common cereal foods and also rich in iodine (I). Existence of vitamin A and vitamin C in the Powders is different point from cereal foods. Vitamin $B_1\;and\;B_2$ are also relatively rich in the powders.'Vitamin A in ·Sargassum fulvellum is high and the levels of some minerals and vitamins are seemed4 to be some influenced by seasons. 3. In the amino acid composition methionine, isoleucine, Iysine and valine are limiting amino acids. The protein qualities of Sargassum fulvellum and Sargassum patens C.A. are seemed to be .almost same and generally ·good. Seasonal difference in amino acid composition was found. B. Animal feeding experiment 1. The best growth was found at.10% supplemental level of the seaweed Powder and lower growth rate was shown at 30% level. 2. It was shown that 15% supplemental level of the Seaweed powder seems to fulfil, to some extent the mineral requirement of the animals. 3. No any changes were found in organs development except that, in kidney, there found decreasing in weight by increasing the supplemental level of the seaweed powder. 4. There is no any significant changes in nitrogen retention, serum cholesterol, serum calcium and urinary calcium in each supplemental level of the seaweed powder. 5. In animal feeding experiment it was concluded that $5%{\sim}15%$ levels supplementation of the seaweed powder are possible. C. Experimental cooking and acceptability test 1. The seaweed powder showed to be utilized more excellently in foreign cookings than in Korean cookings. Higher supplemental level of seaweed was passible in foreign cookings. 2. Hae-Jo-Kang and Jeon-Byung were more excellent than Song-Pyun, wheat cake, Soo-Je-Bee and wheat noodle. Hae-Je-Kang was excellent in its quality even as high as 5% supplemental level. 3. The higher levels of supplementation were used the more sticky cooking products were obtained. Song-Pyun and wheat cake were palatable and lustrous in 2% supplementation level. 4. In drop cookie the higher levels of supplementation, the more crisp product was obtained, compared with other cookies. 5. Corn cake, thin rice gruel, rice gruel and potato Jeon-Byung were more excellent in their quality than potato Man-Doo and potato noodle. Corn cake, thin rice gruel and rice gruel were excellent even as high as 5% supplementation level. 6. In several cooking Porducts some seaweed-oder was perceived in case of 3% or more levels of supplementation. This may be much diminished by the use of proper condiments. D. Sanitary test It seems that there is no any heavy metals (Cd, Pb, As, Hg) problem in these seaweed Powders in case these Powders are used as supplements to any cereal flours E. Economical analysis The price of the seaweed powder is lower than those of other cereals and that may be more lowered when mass production of the seaweed powder is made in future. The supplement of the seaweed powder to any cereals is also economical with the criterion of animal growth rate. F. It is recommended that these seaweed powders should be developed and used as supplement to any cereal flours or used as other food material. By doing so, both saving of cereals and improvement of individual's nutrition will greatly be achieved. It is also recommended that the feeding experiment for men would be conducted in future.

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.1
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• pp.16-37
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• 2018

In this study, difference in chemical composition of $PM_{2.5}$ observed between the year 2013 and 2015 at six air quality intensive monitoring stations (Bangryenogdo (BR), Seoul (SL), Daejeon (DJ), Gwangju (GJ), Ulsan (US), and Jeju (JJ)) was investigated and the possible factors causing their difference were also discussed. $PM_{2.5}$, organic and elemental carbon (OC and EC), and water-soluble ionic species concentrations were observed on a hourly basis in the six stations. The difference in chemical composition by regions was examined based on emissions of gaseous criteria pollutants (CO, $SO_2$, and $NO_2$), meteorological parameters (wind speed, temperature, and relative humidity), and origins and transport pathways of air masses. For the years 2013 and 2014, annual average $PM_{2.5}$ was in the order of SL ($${\sim_=}DJ$$)>GJ>BR>US>JJ, but the highest concentration in 2015 was found at DJ, following by GJ ($${\sim_=}SJ$$)>BR>US>JJ. Similar patterns were found in $SO{_4}^{2-}$, $NO_3{^-}$, and $NH_4{^+}$. Lower $PM_{2.5}$ at SL than at DJ and GJ was resulted from low concentrations of secondary ionic species. Annual average concentrations of OC and EC by regions had no big difference among the years, but their patterns were distinct from the $PM_{2.5}$, $SO{_4}^{2-}$, $NO_3{^-}$, and $NH_4{^+}$ concentrations by regions. 4-day air mass backward trajectory calculations indicated that in the event of daily average $PM_{2.5}$ exceeding the monthly average values, >70% of the air masses reaching the all stations were coming from northeastern Chinese polluted regions, indicating the long-range transportation (LTP) was an important contributor to $PM_{2.5}$ and its chemical composition at the stations. Lower concentrations of secondary ionic species and $PM_{2.5}$ at SL in 2015 than those at DJ and GJ sites were due to the decrease in impact by LTP from polluted Chinese regions, rather than the difference in local emissions of criteria gas pollutants ($SO_2$, $NO_2$, and $NH_3$) among the SL, DJ, and GJ sites. The difference in annual average $SO{_4}^{2-}$ by regions was resulted from combination of the difference in local $SO_2$ emissions and chemical conversion of $SO_2$ to $SO{_4}^{2-}$, and LTP from China. However, the $SO{_4}^{2-}$ at the sites were more influenced by LTP than the formation by chemical transformation of locally emitted $SO_2$. The $NO_3{^-}$ increase was closely associated with the increase in local emissions of nitrogen oxides at four urban sites except for the BR and JJ, as well as the LTP with a small contribution. Among the meterological parameters (wind speed, temperature, and relative humidity), the ambient temperature was most important factor to control the variation of $PM_{2.5}$ and its major chemical components concentrations. In other words, as the average temperature increases, the $PM_{2.5}$, OC, EC, and $NO_3{^-}$ concentrations showed a decreasing tendency, especially with a prominent feature in $NO_3{^-}$. Results from a case study that examined the $PM_{2.5}$ and its major chemical data observed between February 19 and March 2, 2014 at the all stations suggest that ambient $SO{_4}^{2-}$ and $NO_3{^-}$ concentrations are not necessarily proportional to the concentrations of their precursor emissions because the rates at which they form and their gas/particle partitioning may be controlled by factors (e.g., long range transportation) other than the concentration of the precursor gases.

• Journal of Food Hygiene and Safety
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• v.34 no.1
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• pp.22-29
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• 2019

Validamycin A is an aminoglycoside fungicide produced by Streptomyces hygroscopicus that inhibits trehalase. The purpose of this study was to develop a method for detecting validamycin A in agricultural samples to establish MRL values for use in Korea. The validamycin A residues in samples were extracted using methanol/water (50/50, v/v) and purified with a hydrophilic-lipophilic balance (HLB) cartridges. The analyte was quantified and confirmed by 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 (0.005~0.5 ng) into a blank extract with $R^2$ > 0.99. The limits of detection and quantification were 0.005 and 0.01 mg/kg, respectively. For validation validamycin A, recovery studies were carried out three different concentration levels (LOQ, $LOQ{\times}10$, $LOQ{\times}50$, n = 5) with five replicates at each level. The average recovery range was from 72.5~118.3%, with relative standard deviation (RSD) less than 10.3%. All values were consistent with the criteria ranges requested in the Codex guidelines (CAC/GL 40-1993, 2003) and the NIFDS (National Institute of Food and Drug Safety) guideline (2016). Therefore, the proposed analytical method is accurate, effective and sensitive for validamycin A determination in agricultural commodities.

• Journal of Food Hygiene and Safety
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• v.34 no.3
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• pp.227-234
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• 2019

An analytical method was developed for the determination of oxytetracycline in agricultural products using the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method by liquid chromatography-tandem mass spectrometry (LC-MS/MS). After the samples were extracted with methanol, the extracts were adjusted to pH 4 by formic acid and sodium chloride was added to remove water. Dispersive solid phase extraction (d-SPE) cleanup was carried out using $MgSO_4$ (anhydrous magnesium sulfate), PSA (primary secondary amine), $C_{18}$ (octadecyl) and GCB (graphitized carbon black). The analytes were quantified and confirmed with LC-MS/MS using ESI (electrospray ionization) in positive ion MRM (multiple reaction monitoring) mode. The matrix-matched calibration curves were constructed using six levels ($0.001{\sim}0.25{\mu}g/mL$) and coefficient of determination ($r^2$) was above 0.99. Recovery results at three concentrations (LOQ, $10{\times}LOQ$, and $50{\times}LOQ$, n=5) were from 80.0 to 108.2% with relative standard deviations (RSDs) less than of 11.4%. For inter-laboratory validation, the average recovery was in the range of 83.5~103.2% and the coefficient of variation (CV) was below 14.1%. All results satisfied the criteria ranges requested in the Codex guidelines (CAC/GL 40-1993, 2003) and the Food Safety Evaluation Department guidelines (2016). The proposed analytical method was accurate, effective and sensitive for oxytetracycline determination in agricultural commodities. This study could be useful for safety management of oxytetracycline residues in agricultural products.