• Journal of The Korean Society of Grassland and Forage Science
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• v.39 no.2
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• pp.114-120
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• 2019

This study was carried out to explore the accuracy of near infrared spectroscopy(NIRS) for the prediction of moisture content and chemical parameters on winter annual forage crops. A population of 2454 winter annual forages representing a wide range in chemical parameters was used in this study. Samples of forage were scanned at 1nm intervals over the wavelength range 680-2500nm and the optical data was recorded as log 1/Reflectance(log 1/R), which scanned in intact fresh condition. The spectral data were regressed against a range of chemical parameters using partial least squares(PLS) multivariate analysis in conjunction with spectral math treatments to reduced the effect of extraneous noise. The optimum calibrations were selected based on the highest coefficients of determination in cross validation($R^2$) and the lowest standard error of cross-validation(SECV). The results of this study showed that NIRS calibration model to predict the moisture contents and chemical parameters had very high degree of accuracy except for barely. The $R^2$ and SECV for integrated winter annual forages calibration were 0.99(SECV 1.59%) for moisture, 0.89(SECV 1.15%) for acid detergent fiber, 0.86(SECV 1.43%) for neutral detergent fiber, 0.93(SECV 0.61%) for crude protein, 0.90(SECV 0.45%) for crude ash, and 0.82(SECV 3.76%) for relative feed value on a dry matter(%), respectively. Results of this experiment showed the possibility of NIRS method to predict the moisture and chemical composition of winter annual forage for routine analysis method to evaluate the feed value.

• Journal of Food Hygiene and Safety
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• v.34 no.1
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• pp.30-39
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• 2019

An analytical method was developed for the determination of sedaxane in agricultural products using liquid chromatograph-tandem mass spectrometry (LC-MS/MS). The samples were extracted with acetonitrile and partitioned with dichloromethane to remove the interference, and then purified by using silica SPE cartridges to clean up. The analytes were quantified and confirmed by using LC-MS/MS in positive ion mode using multiple reaction monitoring (MRM). The matrix-matched calibration curves were linear over the calibration ranges ($0.001-0.25{\mu}g/mL$) into a blank extract with $r^2$>0.99. For validation, recovery tests were carried out at three different concentration levels (LOQ, 10LOQ, and 50LOQ, n=5) with five replicates performed at each level. The recoveries were ranged between 74.5 to 100.8% with relative standard deviations (RSDs) of less than 12.1% for all analytes. All values were consistent with the criteria ranges requested in the Codex guidelines (CAC/GL 40, 2003) and Food Safety Evaluation Department guidelines (2016). The proposed analytical method was accurate, effective and sensitive for sedaxane determination in agricultural commodities.

• Journal of Food Hygiene and Safety
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• v.34 no.3
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• pp.242-250
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• 2019

An analytical method was developed for the determination of fenquinotrione, a triketone herbicide, in agricultural products. Fenquinotrione was metabolized to KIH-3653-M-2 in plants. Analyte extraction was conducted using 2% formic acid in acetonitrile and cleaned up using a hydrophillic-lipophillic balance (HLB) cartridge. The limits of detection (LOD) and quantification (LOQ) were 0.004 and 0.01 mg/kg, respectively. Matrix-matched calibration curves were linear over the calibration ranges ($0.001{\sim}0.1{\mu}g/mL$) into a blank extract with $r^2>0.99$. The recovery results for fenquinotrione and KIH-3653-M-2 ranged between 81.1 to 116.2% and 78.0 to 110.0% at different concentration levels (LOQ, $10{\times}LOQ$, $50{\times}LOQ$) with relative standard deviation (RSD) less than 4.6%. All values were corresponded with the criteria ranges requested in both the Codex (CAC/GL 40-1993, 2003) and MFDS guidelines (2016). Therefore, the proposed method can be used as an official analytical method for determination of fenquinotrione in the Republic of Korea.

• Journal of the Korean Society of Radiology
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• v.8 no.6
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• pp.293-299
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• 2014

Compton suppression device is a device by using the Compton scattering reaction and suppress the Compton continuum portion of the spectrum, so can be made more clear analysis of gamma ray peak in the Compton continuum region. Measurements above background occurs or, radioactivity counts of radioactivity concentration value of $^{40}K$ nuclides $^{137}Cs$ and natural radioactivity artificial radioactivity detected from the surface soil sample, unwanted non-target analysis and interference peak who dotted line you know the calibration of the measurement energy is allowed to apply the (Compton suppression) non-suppressed spectrum inhibition spectrum and (Compton Unsuppression) the background to the measured value of the activity concentration value of the standard-ray source is detected relative to the peak of By measuring according to the different distances cause $^{137}Cs$, and comparative analysis of the Monte Carlo simulation, in order to obtain a detection capability for efficient, looking at the Compton inhibitor, as the CSF value increases with increase in the distance, more It was found that the background due to Compton continuum of the measured spectrum suppression mode Compton unrestrained mode can know that the Compton suppression many were made, using a $^{137}Cs$ is reduced.

• The Korean Journal of Pesticide Science
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• v.17 no.1
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• pp.65-71
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• 2013

The modified QuEChERS method was evaluated for rapid determination of pesticide residues in spinach by gas chromatography-nitrogen phosphorous detector (NPD) and electron capture detector (ECD). Fifty GC-amenable pesticides which were most frequently detected in monitoring were selected in the current study. Matrix-matched calibration was performed. The detector response for all pesticides was linear with determination coefficients higher than 0.995. LODs for most compounds ranged between 0.001 and 0.1 ug/g, and about 90% of the compounds had LODs of less than 0.05 ug/g. LOQs ranged from 0.001 to 0.32 ug/g, which were well below the MRLs permitted for most of pesticides. In the majority of cases, the recoveries (80-120%) and relative standard deviations (RSDs) (less than 20%) were within acceptable levels except for dichlorvos, propamocarb, chlorothalonil, dichlofluanid, cyhalothrin and fenvalerate. Also, this method which is applied to routine samples showed good results when comparing with traditional multi-residue method.

• Journal of the Korean Chemical Society
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• v.59 no.3
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• pp.225-232
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• 2015

A liquid chromatography-electrospray ionization-tandem mass spectrometry method (LC-ESI-MS/MS) was used for determining seven pesticides (2,4-dichlorophenoxyacetic acid, methomyl, aldicarb, 2-methyl- 4-chlorophenoxy- acetic acid, molinate, carbaryl and carbofuran) and two synthetic materials (quinoline and bisphenol-A) in surface water. The analytes were extracted using solid-phase extraction (SPE). The eluate was concentrated by nitrogen gas. 100 microliters of 30% (v/v) methanol aqueous solution were used to dissolve the residue and an aliquot of the reconstituted solution was directly injected into LC-ESI-MS/MS after the filtration using 0.2 μm polytetrafluoroethylene (PTFE) syringe filter. Under the established condition, the calibration curves of the analytes were linear with correlation coefficients of above 0.997. The quantification limit was 0.002~0.011 μg/L and the relative standard deviations were less than 16.4%. In addition, accuracy was in the range of 84~107% and the recoveries were values between 56.2 and 98.6%. In this study, the developed method was applied to the analysis of real surface water samples.

• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.553-558
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• 2012

A simple new method was developed for the determination of betaine in Fructus Lycii using hydrophilic interaction liquid chromatography with evaporative light scattering detection (HILIC-ELSD). Good chromatographic separation and reasonable betaine retention was achieved on a Kinetex HILIC column ($2.1{\times}100mm$, $2.6{\mu}m$) packed with fused-core particle. The mobile phase consisted of (A) acetonitrile and (B) 10 mM ammonium formate (pH 3.0)/acetonitrile (90/10, v/v). It was used with gradient elution at a flow rate of 0.7 mL/min. The column temperature was set at $27.5^{\circ}C$ and the injection volume was $10{\mu}L$. The ELSD drift tube temperature was $50^{\circ}C$ and the nebulizing gas (nitrogen) pressure was 3.0 bar. Stachydrine, a zwitterionic compound, was used as an internal standard. Calibration curve over $10-250{\mu}g/mL$ showed good linearity ($R^2$ > 0.9992) and betaine in the 70% methanol extract of Fructus Lycii was well separated from other peaks. Intraand inter-day precision ranged from 1.1 to 3.0% and from 2.4 to 5.3%, respectively, while intra- and inter-day accuracy ranged from 100.0 to 107.0% and from 94.3 to 103.9%, respectively. The limit of quantification (LOQ) was $10{\mu}g/mL$ and the recoveries were in the range of 98.2-102.7%. The developed HILIC-ELSD method was successfully applied to quantitatively determine the amount of betaine in fourteen Fructus Lycii samples from different locations, demonstrating that this method is simple, rapid, and suitable for the quality control of Fructus Lycii.

• The Korean Journal of Pesticide Science
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• v.17 no.3
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• pp.162-167
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• 2013

An analytical method for the simultaneous determination of pencycuron in agricultural products was established by using GC-NPD. The method was validated through the guidelines of linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy and precision. The calibration curve of pencycuron was linear over the concentration range of 0.02-2 mg/kg with correlation coefficient of above 0.9999. The limits of detection and quantification were 0.005 and 0.02 mg/kg. Mean recoveries of pencycuron for each sample were 79.6-107.5% at the level of 0.02 mg/kg and 86.4-112.1% at the level of 0.2 mg/kg and 84.0- 104.9% at the level of 1 mg/kg. Relative standard deviation (RSD) in recoveries were all less than 5%. The intra- and inter-day precision (RSD) were 1.6-3.0% and 5.3-11.5%, respectively. The result of validation indicated that this method was accurate and sensitive assay.

• Journal of the Korean Chemical Society
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• v.40 no.8
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• pp.542-548
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• 1996

Electrodes modified with threonine, methionine and serine as ligands, which are incorporated by ion exchange into a polycationic film of electropolymerized $[Ru(v-bpy)_3]^{2+}$, have been employed in the determination of mercury in solution. The redox response of the surface-immobilized mercury/ligand complex was used as the analytical signal. When the polymeric film was electropolymerized, the supporting electrolytes were TBAP and $KPF_6$ to compare the morphology and anodic stripping of resulted polymer electrodes. At the case of the latter, the film had high porosity to give an easy incorporation of dopant anions into polymeric film matrix and a high sensitivity in determination of mercury ion. Especially, this polymer modified electrode exhibited possibility of multiple use in mercury determination over ten times. In all cases, calibration curves which were plotted by log of the surface coverage-normalized redox response vs. log[Hg] exhibited an excellent correlation (r=0.99) for mercury concentrations ranging from 1.0{\times}10^{-8}{\sim}1.0{\times}10^{-2}M$. At these curves relative standard deviation was 5∼8% and saturation response was not observed at high concentration region. Serine of the employed ligands had the best sensitivity in analytical application, which had greater stability constant in forming a complex with mercury than others as $pK_{Hg}=8.54$. The formation constants of threonine and methionine were respectively 7.04 and 7.80.

• Journal of the Korean Chemical Society
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• v.60 no.2
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• pp.118-124
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• 2016

Parabens were commonly used for preventing the growth of microorganisms as preservatives in the pharmaceutical, cosmetic and food industry. Also, parabens are known endocrine disruptors because of their estrogenic effects on human. Parabens affect the endocrine system and show adverse effect such as, genital malformations, precocious puberty and testicular cancer in young children, infants and fetuses. In this study, we developed analytical method for four parabens (methyl paraben, ethyl paraben, propyl paraben, butyl paraben) in human breast milk which frequently consumed by newborn baby. The analytes were extracted using liquid-liquid extraction (LLE) after enzyme hydrolysis with protease and lipase, then quantitative analysis was performed by liquid chromatography tandem mass spectrometry (LC-MS/MS). The method validation results were as follows; the linearity of calibration curves were excellent with coefficient of determinations (r²) higher than 0.999, the limit of detections (LODs) were 0.019~0.044 ng/mL, the accuracies were 85.3~105.9% and the precisions were lower than 10%. The average concentration ± standard deviation of parabens in ten human breast milk sample were MP 0.660 ± 0.519 ng/mL, EP 1.631 ± 2.081 ng/mL and PP 0.326 ± 0.320 ng/mL, and BP was not detected.