• Journal of the Korean Society of International Agriculture
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• v.30 no.4
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• pp.339-346
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• 2018

Cyanazine is a member of the triazine family of herbicides. Cyanazine is used as a pre- and post-emergence herbicide for the control of annual grasses and broadleaf weeds. This experiment was conducted to establish a determination method for cyanazine, as domestic unregistered pesticide, residue in major agricultural commodities using HPLC-DAD/MS. Cyanazine was extracted with acetone from representative samples of five raw products which comprised apple, green pepper, Kimchi cabbage, hulled rice and soybean. The extract was diluted with saline water and partitioned to dichloromethane for remove polar extractive in the aqueous phase. For the hulled rice and soybean samples, n-hexane/acetonitrile partition was additionally employed to remove non-polar lipids. The extract was finally purified by optimized florisil column chromatography. On a $C_{18}$ column in HPLC, cyanazine was successfully separated from co-extractives of sample, and sensitively quantitated by diode array detection at 220 nm. Accuracy and precision of the proposed method was validated by the recovery experiment on every major agricultural commodity samples fortified with cyanazine at 3 concentration levels per agricultural commodity in each triplication. Mean recoveries were ranged from 83.6 to 93.3% in five major representative agricultural commodities. The coefficients of variation were all less than 10%, irrespective of sample types and fortification levels. Limit of quantitation(LOQ) of cyanazine was 0.02 mg/kg as verified by the recovery experiment. A confirmatory method using LC/MS with selected-ion monitoring(SIM) technique was also provided to clearly identify the suspected residue.

• Korean Journal of Food Science and Technology
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• v.52 no.1
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• pp.26-30
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• 2020

This study was undertaken to determine the characteristics of xanthoangelol, the major chalcone constituent derived from the extracts of different parts of Lespedeza bicolor. Xanthoangelol was isolated from the root extract using column chromatography and used as a standard for quantitative analysis. The structure of the isolated compound was established based on spectroscopic evidence. The HPLC-DAD method was validated for specificity, linearity, precision, accuracy, limit of detection, and limit of quantitation. The calibration curve of xanthoangelol had significant linearity (R²>0.9999). Limit of detection and limit of quantitation 0.018 and 0.059 ㎍/mL, respectively. The relative standard deviation values of precision test, and intra- and inter-day tests were less than 0.22 and 0.40%, respectively. In the recovery test, the accuracy ranged from 98.98-102.78% with RSD values less than 0.13%. The method validation parameters indicate the applicability of the HPLC method for quality control of food or drug formulations containing L. bicolor.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.7A
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• pp.746-754
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• 2007

In this paper, we propose a fast handoff algorithm for micromobility management enhancement in HMIPv6 networks, which eliminates the DAD procedure involved in the regular HMIPv6 in order to o decrease handoff latency and increase the resource utilization efficiency. In the proposed scheme, the MAP is designed to guarantee the uniqueness of MN's interface identifier within a MAP domain as long as the MN moves in a MAP domain, so that the MN configures the new address without the DAD procedure resulting in the decreased handoff latency significantly When the MN resides in a subnet, MIPv6 is used adaptively as a mobility management protocol, which is to reduce bandwidth waste from the IP packet header overhead of IP-in-IP tunneling from the regular HMIPv6. We evaluate the performance of the proposed handoff micromobility algorithm in terms of handoff delay and packet loss thru computer simulation. Thru various computer simulation results, we verified the superior performance of the proposed scheme by comparing with the results of other schemes, MIPv6 and HMIPv6.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5B
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• pp.257-269
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• 2007

This paper proposes a novel method to perform a quantitative analysis of message complexity and applies this method in comparing the message complexity among the mobile ad hoc network (MANET) address autoconfiguration protocols (AAPs). To obtain the upper bound of the message complexity of the protocols, the O-notation of a MANET group of N nodes has been applied. The message complexity of the single node joining case in Strong DAD, Weak DAD with proactive routing protocols (WDP), Weak DAD with on-demand routing protocols (WDO), and MANETconf has been derived as n(mO(N)+O(t)), n(O(N)+O(t)), n(O(N)+2O(t)), and nO((t+1)N)+O(N)+O(2) respectively. In order to verify the bounds, analytical simulations that quantify the message complexity of the address autoconfiguration process based on the different coflict probabilities are conducted.

• Analytical Science and Technology
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• v.19 no.6
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• pp.519-528
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• 2006

An analytical method for the determination of thyroid hormones in urine samples has been studied by using solid-phase extraction and high-performance liquid chromatography/diode array detector/electro-spray mass spectrometry. Seven thyroid hormones were successfully separated by gradient elution on the reverse phase Hypersil ODS column (4.6 mm I.D., 100 mm length, particle size $5{\mu}m$) with ammonium formate buffer and acetonitrile, and UV spectra and mass fragment could be confirmed. The extraction recoveries of thyroid hormones in the urine samples (pH 3) were in the range of 89.0-113.1% with solid-phase extraction by C18, followed by elution with 4 ml of methanol/ammonium hydroxide (9 : 1). The calibration curves showed good linearity with the correlation coefficients ($r^2$) varying from 0.992 to 0.998 and the detection limits of all analytes were obtained in the range of 2-4 ng/ml (3.8-13.0 pmol/ml).

• Korean Journal of Pharmacognosy
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• v.45 no.4
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• pp.294-299
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• 2014

The simultaneous determination of platyphylloside, aceroside and betulin was established for the quality control of Betula platyphylla bark using a high performance liquid chromatography and diode-array UV/Vis detector (HPLC-DAD). Separation and quantification were successfully achieved with a INNO C18 column ($5{\mu}m$, 4.6 mm $I.D.{\times}150mm$) by gradient elution of a mixture of methanol and water at a flow rate of 1.0 ml/min. Validation of the developed method was performed by various factor such as linearity, specificity, precision, accuracy, system suitability and stability. This method was successfully applied to the determination of contents of platyphylloside, aceroside VIII and betulin in three batches of Betula platyphylla bark extract. These results suggest that the developed HPLC method is simple, effective and could be utilized as a quality control method for Betula platyphylla bark products.

• Analytical Science and Technology
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• v.10 no.5
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• pp.315-324
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• 1997

The retention behaviors of 16 PAHs and 4 nitro-PAHs were studied with several parameters involved numbers of carbon atoms, F factor, aqueous solubility, L/B ratio, and numbers of interfering hydrogen atom pairs on the chemical structures of PAHs by using reversed-phase liquid chromatography/diode array detection method (RPLC/DAD) and gradient elution method. It was obtain that the log k' for most of PAHs with increasing the number of carbon and the F factor in their molecules. Chromatographic retention of PAH isomers and nitro-PAHs were examined with aqueous solubility, L/B ratio and number of interfering hydrogen atom pairs. As a result of comparison with these factors and retention times, it was found that those solutes having larger aqueous solubilities and greater L/B ratios were retained longer on stationary phase. This tendency was also occured in the molecules having the more number of interfering hydrogen atom pairs. Detection limits of PAHs which were obtained with three times measurements by RPLC/DAD were in the range of 100~500ng/mL and method detection limit(MDL) for water sample were in the range of 0.1~0.5ng/mL.

• The Journal of Korean Medicine
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• v.25 no.3
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• pp.45-54
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• 2004

Objectives : This study was aimed to evaluate marker substances in Gami-Honghwa-Tang (KH-19) by high performance liquid chromatography-photodiode array detector (HPLC-DAD). Gami-Honghwa-Tang is composed of nine crude herbs, Rehmanniae Radix Preparata, Angelicae Gigantis Radix, Cnidii Rhizoma, Paeoniae Radix, Corni Fructus, Moutan Cortex Radicis, Lycii Fructus, Carthami Flos and Glycyrrhizae Radix. Methods : The separation was performed on an Aquasil C18 (4.6×250mm) column by gradient elution with 0.05% TFA in H2O - 0.05% TFA in acetonitrile (0 min 100:0, 20 min 90:10, 40 min 70:30, 60 min 50:50, 80 min 0:100, 90 min 100:0) as the mobile phase at a flow-rate of 1.0 ml/min with detection at 190-800nm. Also we examined the contents for bacteria, pesticide residue and harmful heavy metals. Results : HPLC-DAD was employed to determine the quantities and the qualities of several marker substances such as 5­hydroxymethyl-2-furaldehyde (5-HMF), paeonol, loganin, paeoniflorin, glycyrrhizin, and decursin in the KH-19. There were no bacterial contents, pesticide residues, or harmful heavy metals. Conclusions : We suggest these results could be a useful evidence for quality control of KH-19. This method permits fingerprints of selected individual marker substances from herbal prescriptions without derivatization, multiple purification steps, or lengthy separation times.

• Analytical Science and Technology
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• v.36 no.4
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• pp.152-160
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• 2023

Adenosine and cordycepin are bioactive compounds with health benefits. Therefore, both substances are often used to assess the quality of Cordyceps products. Optimization and validation of the HPLC/DAD method for determining two nucleosides were studied. The samples were prepared using an ultrasound-assisted extraction (ultrasonic bath). The result was optimal conditions for aqueous extraction, an extraction time of 35 min, and an extraction temperature of 40 ℃. The Chromatographic separation was achieved using a reverse phase column (InfinityLab Poroshell 120 EC-C18, 4.6 × 250 mm, 2.7 ㎛) at 30 ℃ with a mobile phase gradient elution of water and methanol at a flow rate of 0.7 mL/min. The eluents were monitored via a diode array detector at 260 nm. Two nucleosides were separated by less than 12 min after injection. The developed method was found to be excellent linear (r² > 0.9999), accurate (% recovery 95.34-98.51), and precise (% relative standard deviation < 2.0). The limit of detection (LOD) and quantification (LOQ) were 0.45 and 1.38 mg/mL for adenosine and 0.47 and 1.43 mg/mL for cordycepin, respectively. This method was satisfactory for simultaneously quantitating two nucleoside contents, which were used to evaluate Cordyceps products.

• Journal of Korea Water Resources Association
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• v.48 no.2
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• pp.115-126
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• 2015

In recent years, debris flow disaster has occurred in multiple locations between high and low mountainous areas simultaneously with a flooding disaster in urban areas caused by heavy and torrential rainfall due to the changing global climate and environment. As a result, these disasters frequently lead to large-scale destruction of infrastructures or individual properties and cause psychological harm or human death. In order to mitigate these disasters more effectively, it is necessary to investigate what causes the damage with an integrated model of both disasters at once. The objectives of this study are to analyze the mechanism of debris flow for real basin, to determine the PMP and run-off discharge due to the DAD analysis, and to estimate the influence range of debris flow for fan area according to the scenario. To analyse the characteristics of debris flow at the real basin, the parameters such as the deposition pattern, deposit thickness, approaching velocity, occurrence of sediment volume and travel length are estimated from DAD analysis. As a results, the peak time precipitation is estimated by 135 mm/hr as torrential rainfall and maximum total amount of rainfall is estimated by 544 mm as typhoon related rainfall.