• Progress in Medical Physics
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• v.17 no.3
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• pp.179-186
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• 2006

Purpose: Photon beam data of linear accelerators in Korea are collected, analyzed, and a simple method for checking and verifying the dose calculations in a TPS are suggested. Materials and Methods: Photon beam data such as output calibration condition, output factor, wedge factor, percent depth dose, beam profile, and beam quality were collected from 26 institutions in Korea. In order to verify the accuracy of dose calculation, ten sample planning tests were peformed. These Include square, elongated, and blocked fields, wedge fields, off-axis dose calculation, SSD variation. The planned data were compared to that of manual calculations. Results: The average and standard deviation of photon beam quality for 6, 10, and 15 MV were $0.576{\pm}0.005,\;0.632{\pm}0.004,\;and\;0.647{\pm}0.006$, respectively. The output factors of 6 MV photon beam measured at depth of dose maximum for $5{\times}5cm,\;15{\times}15cm,\;20{\times}20cm\;were\;0.944{\pm}0.006,\;1.031{\pm}0.006,\;and\;1.055{\pm}0.007$. For 10 MV photon beam, the values were $0.935{\pm}0.006,\;1.031{\pm}0.007,\;1.054{\pm}0.0005$. The collected data were not enough to calculate average, the output factors for 15MV photon beam with field size of $5{\times}5cm,\;15{\times}15cm,\;20{\times}20cm\;were\;0.941{\pm}0.008,\;1.032{\pm}0.004,\;1.049{\pm}0.014$. There was seven institutions $e{\times}ceeding$ tolerance when monitor unit values calculated from treatment planning system and manually were compared. The measured average MU values for the machines calibrated at SAD setup were 3 MU and 5 MU higher than the machines calibrated at SSD for 6 MV and 10 MV, respectively except the wedge case. When the wedges were inserted, the MU values to deliver 100 cGy to 5 cm depends on manufactures. When the same wedge angle was used, Siemens machine requires more MUs then Varian machine. Conclusion: In this study, photon beam data are collected and analyzed to provide a baseline value for chocking beam data and the accuracy of dose calculation for a treatment planning system.

• Korean Journal of Environmental Agriculture
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• v.32 no.1
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• pp.70-77
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• 2013

BACKGROUND: Nitroxoline is an antibiotic agent. It is used for the treatment of the second bacterial infection by the colibacillosis, salmonellosis and viral disease of the poultry. When the nitroxoline is indiscreetly used, the problem about the abuse of the antibiotics can occur. Therefore, this study presented the residue analytical method of nitroxoline in food for the safety management of animal farming products. METHODS AND RESULTS: A simple, sensitive and specific method for nitroxoline in chicken muscle by high performance liquid chromatograph with PDA was developed. Sample extraction with acetonitrile, purification with SPE cartridge (MCX) were applied, then quantitation by HPLC with C18 column under the gradient condition with 0.1 % tetrabutylammonium hydroxide-phosphoric acid and methanol was performed. Standard calibration curve presented linearity with the correlation coefficient ($r^2$) > 0.999, analysed from 0.02 to 0.5 mg/L concentration. Limit of quantitation in chicken muscle showed 0.02 mg/kg, and average recoveries ranged from 72.9 to 88.1 % in chicken muscle. The repeatability of measurements expressed as coefficient of variation (CV %) was less than 12 % in 0.02 and 0.04 mg/kg. CONCLUSION(S): Newly developed method for nitroxoline in chicken muscle was applicable to food inspection with the acceptable level of sensitivity, repeatability and reproducibility.

• Journal of Environmental Impact Assessment
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• v.27 no.2
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• pp.124-138
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• 2018

This research was conducted to examine the availability of spatial data for assessing absorption rates of $CO_2$ in the forest of Ansan-si and evaluate the validity of methods that analyze $CO_2$ absorption. To statistically assess the $CO_2$ absorption rates per year, the 1:5,000 Digital Forest-Map (Lim5000) and Standard Carbon Removal of Major Forest Species (SCRMF) methods were employed. Furthermore, Land Cover Map (LCM) was also used to verify $CO_2$ absorption rate availability per year. Great variations in $CO_2$ absorption rates occurred before and after the year 2010. This was due to improvement in precision and accuracy of the Forest Basic Statistics (FBS) in 2010, which resulted in rapid increase in growing stock. Thus, calibration of data prior to 2010 is necessary, based on recent FBS standards. Previous studies that employed Lim5000 and FBS (2015, 2010) did not take into account the $CO_2$ absorption rates of different tree species, and the combination of SCRMF and Lim5000 resulted in $CO_2$ absorption of 42,369 ton. In contrast to the combination of SCRMF and Lim5000, LCM and SCRMF resulted in $CO_2$ absorption of 40,696 ton. Homoscedasticity tests for Lim5000 and LCM resulted in p-value <0.01, with a difference in $CO_2$ absorption of 1,673 ton. Given that $CO_2$ absorption in forests is an important factor that reduces greenhouse gas emissions, the findings of this study should provide fundamental information for supporting a wide range of decision-making processes for land use and management.

• Journal of Food Hygiene and Safety
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• v.20 no.3
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• pp.141-146
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• 2005

A simple and sensitive analysis method based on reverse phase (RP) HPLC with UV detector was developed for simultaneous determination of chlorophyll a and b, pheophorbide a and $\beta-Carotene$ in Chlorella and Spirulina products. For added concentration $(50\;\mug/ml)$ of chlorophyll a and b, pheophorbide a and $\beta-Carotene$, recoveries of those were 70.3, 71.6, 60.1 and $90.5\%$, respectively, with relative standard deviations of 2.8,6.0, 10.6 and $10.4\%$. Limit of detection and quantification had ranges of $0.1\sim1.0\;\mug/ml$ and $0.2\sim2.0\;\mug/ml$, respectively. Calibration curve was linear with correlation coefficient of 0.995 for chlorophyll a and b, pheophorbide a and $\beta-Carotene$. Results of simultaneous determination in Chlorella and Spirulina products were showed ranges of $121.g\sim543.0\;\mug/ml$ for chlorophyll a,$0.6\sim160.0\;\mug/ml$ for chlorophyll b, $19.2\sim60.3\;\mug/ml$ for pheophorbide a and $383.6\sim1713.7\;\mug/ml$ for $\beta-Carotene$, respectively. Chlorophyll b contents in Chlorella products were detected above 30 times level to those in Spirulina products. $\beta-Carotene$ contents in Spirulina products were detected 2.7 times level to those in Chlorella products.

• Journal of Food Hygiene and Safety
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• v.26 no.1
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• pp.16-24
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• 2011

A method was established for the simultaneous determination of sugar alcohols, erythritol, xylitol, sorbitol, inositol, mannitol, maltitiol, lactitol and isomalt by High Performance Liquid Chromatography (HPLC). The sugar alcohols were converted into strong ultraviolet (UV)-absorbing derivatives with p-nitrobenzoyl chloride (PNBC). HPLC was performed on Imtakt Unison US-$C_18$ column, using acetonitrile: water (77:23) as a mobile phase and UV detection (260 nm). The calibration curves for all sugar alcohols tested were linear in the 10~200 mg/L range. The average recoveries of the sugar alcohols from three confectioneries spiked at 100 ppm of eight sugar alcohol standards ranged from 81.2 to 123.1% with relative standard deviations ranging fromo 0.2 to 4.9%. The limits of detection (LODs) were $0.5{\sim}8\;{\mu}g/L$ and the limits of quantification (LOQs) were $2{\sim}17\;{\mu}g/L$. Reproducibility of 8 sugar alcohols was 0.28~1.97 %RSD. The results of the analysis of confectioneries showed that 89 samples of 130 were detected and the sugar alcohols content of samples investigated varied between 0.4 and 693.7 g/kg. A method for the simultaneous determination of eight sugar alcohols will be used as basic data for control of sugar alcohols in confectioneries, and quality control in food manufacturing.

• Analytical Science and Technology
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• v.24 no.5
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• pp.345-351
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• 2011

A liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI/MS/MS) method was developed and validated for the determination of finasteride in human serum. Beclomethasone was used as internal standard (IS) and liquid-liquid extraction (LLE) using methyl tert-butyl ether (MTBE) was carried out to isolate analyte. The mass transitions monitored in multiple reaction monitoring (MRM) in positive ion mode were m/z 373.2${\rightarrow}$305.2 for finasteride and m/z 409.3${\rightarrow}$391.2 for IS. Retention times of finasteride and IS were 5.81 and 5.46 min, respectively. The limit of quantitation (LOQ) was 0.1 ng/mL and the calibration curve showed good linearity in the range of 0.1~20.0 ng/mL ($R^2$=0.9997). The intra-day assay precision and accuracy were in the range 6.3~10.6% and 97.3~103.6%, respectively, and the inter-day assay precision and accuracy were in the range 0.8~5.2% and 99.8~102.5%, respectively. The sample extract recovery of the method was 80~83%.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.269-277
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• 2014

The multiclass pesticide multiresidue method for the simultaneous determination of diflubenzuron in agricultural products was conducted by using HPLC-UVD. The method was validated through the guidelines of linearity, specificity, limit of detection (LOD), limit of quantification (LOQ), accuracy and precision with pesticide-free spinach, Korean cabbage, eggplant, squash, sweet pepper, cucumber, Korean melon. The calibration curve of diflubenzuron was linear over the concentration range of 0.05-5 mg/kg with correlation coefficient of above 0.99999. The limit of detection and quantification was 0.008 and 0.02 mg/kg. Mean recoveries of diflubenzuron for each sample were 77.5-105.6%. Relative standard deviation (RSD) in recoveries were all less than 20%. The intra-day and inter-day precision (RSD) were 0.4-1.9% and 0.7-1.9%, respectively. The result of validation indicated that this method was accurate and rapid assay.

• Analytical Science and Technology
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• v.28 no.5
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• pp.323-330
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• 2015

Alkaptonuria, a rare inherited metabolic disease, is characterized by a lack of homogentisate dioxygenase and accumulation of homogentisic acid (HGA), leading to homogentisic aciduria, arthritis, and ochronosis. In this study, a rapid analytical method, without an expensive and tedious solid phase extraction step, was developed to quantify HGA in plasma using GC-MS. HGA-spiked pooled plasma samples were subjected to liquid-liquid extraction (LLE) with ethyl acetate, followed by trimethylsilyl derivatization (TMS) and GC-MS quantification using selected ion monitoring. The formation of TMS derivative of the 1 carboxylic and 2 hydroxyl functional groups was performed by reacting BSTFA (with 10% TMCS) for 5 min at 80 ℃. For selected ion monitoring, quantification and confirmation ions were determined based on specific ions (m/z 384, m/z 341 and m/z 252) of the TMS derivative of HGA. Calibration curves of pooled normal plasma specimens showed a linear relationship in the range of 1-100 ng/µL. The precision and accuracy were within a relative standard deviation (RSD) of 1 to 15% and a bias of -5 to 25%. Recoveries were obtained in the range of 99-125% and 95-115% for intra-day and inter-day assay, respectively, at 2, 20 and 80 ng/µL. The limit of detection (LOD) and limit of quantification (LOQ) were 0.4 ng/µL and 4 ng/µL, respectively. No homogentisic acid was excreted from normal Korean plasma samples. Collectively, the results from the present study suggest that this method could be useful for routine diagnosis and therapeutic monitoring of alkaptonuria patients with excellent sensitivity and rapidity.

• Analytical Science and Technology
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• v.31 no.2
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• pp.96-105
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• 2018

This study aimed to improve the method for detecting eight secondary aliphatic amines (SAAs), so as to measure their concentrations in fresh water and tap water samples. NaOH (8 mL, 10 M) and benzenesulfonyl chloride (2 mL) were added to a water sample (200 mL), and the mixture was stirred at $80^{\circ}C$ for 30 min. An additional NaOH solution (10 mL) was added and the stirring was continued for another 30 min. The pH of the cooled mixture was adjusted to 5.5-6.0 by adding HCl (35 %), and the SAAs were extracted using dichloromethane (50 mL). This extraction was repeated once. The extract was then washed with $NaHCO_3$ (15 mL, 0.05 M) and dried over $Na_2SO_4$ (4 g). The extract was finally concentrated to 0.1 mL, of which $1{\mu}L$ was analyzed for SAAs by GC-MS. The linearity of the spike calibration curves was high ($r^2=0.9969-0.9996$). The detection limits of the method ranged from 0.01 to $0.20{\mu}g/L$, and its repeatability and reproducibility (expressed as relative standard deviation) were both less than 10 % (6.6-9.4 %). Its accuracy (measured in percentage error) ranged between 2.4 % and 6.1 %. The established method was applied to the analysis of five surface water and 82 tap water samples. Dimethylamine was the only SAA detected in all the water samples, and its average concentration was $0.79{\mu}g/L$ (range: $0.20-2.54{\mu}g/L$). Therefore, this study improved the analytical method for SAAs in surface water and tap water, and the regional and seasonal concentration distributions were obtained.

• The Korean Journal of Pesticide Science
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• v.21 no.1
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• pp.68-74
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• 2017

An analytical method for detecting metamifop residue in paddy water, soil, and rice with high performance liquid chromatography (HPLC) was developed. Water was extracted with ethyl acetate before analyzing by HPLC. Soil residues were extracted with acetone under acidic condition and after purifying with $Extrelut^{(R)}$ NT, and silica SPE, the residue was analyzed by HPLC. For residue analysis in rice, the procedure involved extraction with acetone, purification with $Extrelut^{(R)}$ NT, partitioning between acetonitrile/hexane, purification with silica SPE cartridge, and analysis by HPLC. The limit of detection (LOD) was 1.0 ng, limit of quantitation (LOQ) was 3.0 ng, and method limit of quantitation (MLOQ) were 0.001 mg/L for paddy water, 0.01 mg/kg for rice and soil, respectively. Standard calibration curve shows linearity from 0.05 mg/kg to 5.0 mg/kg ($R^2=0.9999$). The recoveries in fortified paddy water were $91.3{\pm}3.5%$ (0.01 mg/L level) and $93.2{\pm}6.3%$ (0.05 mg/L level). The recoveries in fortified paddy soils were $92.5{\pm}4.0%$ (0.1 mg/kg level) and $92.7{\pm}4.0%$ (0.5 mg/kg level) in soil A, while, $102.3{\pm}4.4%$ (0.1 mg/kg level) and $98.9{\pm}7.9%$ (0.5 mg/kg level) in soil B, respectively. The recoveries in fortified rice were $93.0{\pm}6.9%$ (0.1 mg/kg level) and $85.0{\pm}3.5%$ (0.5 mg/kg level). This method was proved to be effective and can be used to determine the metamifop residue in paddy water, paddy soil, and rice.