• Mass Spectrometry Letters
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• v.11 no.3
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• pp.59-64
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• 2020

Mertansine, a thiol-containing maytansinoid, is a tubulin inhibitor used as the cytotoxic component of antibody-drug conjugates for the treatment of cancer. Liquid chromatography-tandem mass spectrometry was described for the determination of mertansine in rat plasma. 50-μL rat plasma sample was pretreated with 25 μL of 20 mM tris-(2-carboxyethyl)-phosphine, a reducing reagent, and further vortex-mixing with 50 μL of 50 mM N-ethylmaleimide for 3 min resulted in the alkylation of thiol group in mertansine. Alkylation reaction was stopped by addition of 100 μL of sildenafil in acetonitrile (200 ng/mL), and following centrifugation, aliquot of the supernatant was analyzed by the selected reaction monitoring mode. The standard curve was linear over the range of 1-1000 ng/mL in rat plasma with the lower limit of quantification level at 1 ng/mL. The intra- and inter-day accuracies and coefficient variations for mertansine at four quality control concentrations were 96.7-113.1% and 2.6-15.0%, respectively. Using this method, the pharmacokinetics of mertansine were evaluated after intravenous administration of mertansine at doses of 0.2, 0.5, and 1 mg/kg to female Sprague Dawley rats.

• Fisheries and Aquatic Sciences
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• v.19 no.1
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• pp.3.1-3.6
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• 2016

Phlorotannins are reported to have diverse biological properties. However, no analytical methods for the standardization of phlorotannin preparations have been reported. Herein, we developed and validated an analytical method for the determination of dieckol in phlorotannin extracts (PRT) using high-performance liquid chromatography (HPLC). The optimum HPLC conditions consisted of a Supelco Discovery C18 column stationary phase, a mobile phase (A: 15 % HPLC grade methanol in deionized water, B: methanol), UV detection at 230 nm, and a flow rate of 0.7 mL/min. The optimized chromatographic conditions were validated and exhibited good specificity and linearity ($R^2$ > 0.9994-1.0000). The recoveries were in the range of 100.9-102.3 %. The method had good intermediate (%RSD 1.2) and intra-day (%RSD 0.4-1.7) assay precisions. This HPLC method had good accuracy and quality in the determination of dieckol in PRT.

• International Journal of Concrete Structures and Materials
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• v.18 no.3E
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• pp.145-150
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• 2006

An experiment with the objective of providing guidelines for joint depth determination and timing of contraction joint sawcutting to avert uncontrolled cement concrete pavement cracking has been conducted. Theoretical analysis and laboratory tests were performed to help in understanding and analyzing the field observation. Using two-dimensional elastic fracture mechanics, the influence of several parameters on crack propagation was delineated by a parametric study, involving initial notch ratio, joint spacing, Young's modulus and thermal expansion coefficient of concrete, temperature gradient, and modulus of subgrade reaction. Bimaterials made of rock plus cement mortar and rock plus polymer mortar were applied to the concrete in a field test section, and they were subjected to fracture tests. These tests have shown that fracture mechanics is a powerful tool not only in judging the quality of the jointed cement concrete pavement but also in providing a criterion for crack propagation and delamination. Based on fracture mechanics, a method is proposed to determine the joint depth, sawcut timing, and spacing of the jointed cement concrete pavement. This method has successfully been applied to a test section in Seohaean expressway. This study also summarizes the research results obtained from a field test for jointed plain concrete pavement, which was also carried out on the Seohaean expressway.

• Journal of Biosystems Engineering
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• v.37 no.5
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• pp.319-326
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• 2012

Purpose: Cheese texture is an important sensory attribute mainly considered for consumers' acceptance. The feasibility of nondestructive measurements of cheese texture was explored using non-contact ultrasonic sensors. Methods: A novel non-contact air instability compensation ultrasonic technique was used for five varieties of hard cheeses to measure ultrasonic parameters, such as velocity and attenuation coefficient. Five texture properties, such as fracturability, hardness, springiness, cohesiveness, and chewiness were assessed by a texture profile analysis (TPA) and correlated with the ultrasonic parameters. Results: Texture properties of five varieties of hard cheese were estimated using ultrasonic parameters with regression analysis models. The most effective model predicted the fracturability, hardness, springiness, and chewiness, with the determination coefficients of 0.946 (RMSE = 21.82 N), 0.944 (RMSE = 63.46 N), 0.797 (RMSE = 0.06 ratio), and 0.833 (RMSE = 17.49 N), respectively. Conclusions: This study demonstrated that the non-contact air instability compensation ultrasonic sensing technique can be an effective tool for rapid and non-destructive determination of cheese texture.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.3
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• pp.397-409
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• 2004

There has been few studies of either domestic or international to apply CCT-ICP-MS for the precise analysis of As and Cr components associated with airborne particulate matter. To date, the use of CCT-ICP-MS is strongly recommended for the accurate analysis of the toxic trace metals; this is because CCT-ICP-MS technique prevents polyatomic spectral interferences involved in the determination of As and/or Cr components. Taking advantage of CCT-ICP-MS technique, the measurements of about 20 metals were undertaken in this study. The standard reference material (NIST SRM 2783) was used for analytical quality control. To improve analytical accuracy and of acid efficiency, we selected nitric acid based on a test of three kinds of acid for microwave digestion method 1 ) nitric acid. 2) nitric acid and hydrogen peroxide. and 3) nitric acid and perchloric acid. When this method was employed, relative errors to SRM values of Al, As, Cr Fe, Mg, Mn, Pb, Sb, V, and Zn fell below 20%, while those or Ca, Si, and Ti were higher than 20%. The overall results of our study show that the concentrations of As and V determined by CCT-ICP-MS were satisfied with the certificated values within a relative error of 20e1c, whereas those determined by ICP-MS were 10 times higher than the certificated values.

• Korean Journal of Pharmacognosy
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• v.37 no.1 s.144
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• pp.33-36
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• 2006

The quantitative analytical method for the content of dioscin in Dioscorea rhizoma using a high performance liquid chromatography(HPLC) system was established for its quality control. After extracting Discorea rhizoma flour with ethanol, dioscin was separated though an ODS column with a flow rate of 1.0ml/min of acetonnitril-methanol-0.01 M phosphate buffer (pH 5.0)(6:3:1, v/v%), and the amount of dioscin was detected at 210nm. Relation time of dioscin in HPLC chromatogram were about $7.45{\pm}0.34\;min$ and calibration curve showed good linearity at concentrations from 0.1 to 2.0 mg/ml of dioscin. When 5 commercial Dioscorea rhizoma flours were analyzed by HPLC, the peak for dioscin was well separated from others in ethanol extract of Dioscorea rhizoma, and the amount of dioscin was in the range from 0.076 to 0.142(w/w)%.

• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.631-640
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• 2004

This research was conducted to understand the magnitude and nature of the stormwater emissions with the goal of quantifying stormwater pollutant concentrations and mass emission rates of pollutants. Eight highway sites in Southern California area were monitored for three years with collecting of grab and flow-weighted composite samples, rainfall and runoff flow. Generally the EMCs cannot be determined by simple statistical averaging of measured pollutant concentrations because of random characteristics of runoff quality and quantity. Therefore, this manuscripts will show a new EMC determination method. The EMC ranges of 95% confidence intervals are 102.78-216.37mg/L for TSS, 104.53-251.79mg/L for COD, 5.42-10.58mg/L for oil & grease and 2.42-10.18mg/L for TKN. The ranges of washed-off mass loading are determined to $0.06g/m^2-17.27g/m^2$ for TSS and $0.1-3.23g/m^2$for COD.

• Analytical Science and Technology
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• v.28 no.1
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• pp.17-25
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• 2015

A rapid, sensitive and specific method was developed and validated using electrospray ionization (ESI) tandem mass spectrometry (LC-MS/MS) for determination of misoprostol acid in human plasma. Misoprostol $acid-d_5$ was used as in internal standard (IS). The analyte and IS were extracted by simple one step solid phase extraction (SPE). Linearity in plasma was obtained over the concentration range 10~3000 pg/mL and lower limit of quantification (LLOQ) was identifiable and reproducible at 10 pg/mL. The intra- and inter-day precision values were below 9% and the accuracy was ranged from 93.81% to 102.02% at all four quality control samples. The method was has been successfully applied for routine assay to support pharmacokinetic study of misoprostol acid in human plasma after an oral administration of 0.4 mg misoprostol.

• Journal of Biosystems Engineering
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• v.37 no.6
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• pp.398-403
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• 2012

Purpose: Green soybeans (edamame) are now an economically important and popular food product in Japan. In order to shorten breeding time and to decide an optimal harvest time, we have been developing a dedicated NIRT spectrometer since 2004 for the determination of constituent content such as sucrose and free amino acids, which are two major contributors to the eating quality, in a single pod green soybean. Methods: The obtained models showed that the developed NIRT instrument had reasonable accuracy for the determination of these two components. Then we carried out the investigation into the change in two components during a few days storage using these models with changing time, variety/cultivar, packaging and temperature. Results: The result showed that the most affecting factor on decreasing both sucrose content and free amino acids was variety/cultivar. The time, packaging and temperature also affected significantly in most cases.

• Journal of Biosystems Engineering
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• v.43 no.3
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• pp.229-236
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• 2018

Purpose: Makgeolli is a traditional alcoholic beverage made from rice with a fermentation starter called "nuruk." The concentration of alcohol in makgeolli depends on the temperature of the fermentation tank. It is important to monitor the alcohol concentration to manage the makgeolli production process. Methods: Data were collected from 84 makgeolli fermentation tanks over a year period. Independent variables included the temperatures of the tanks and the room where the tanks were located, as well as the quantity, acidity, and water concentration of the source. Software for the multilayer perceptron model (MLP) was written in Python using the Scikit-learn library. Results: Many models were created for which the optimization converged within 100 iterations, and their coefficients of determination $R^2$ were considerably high. The coefficient of determination $R^2$ of the best model with the training set and the test set were 0.94 and 0.93, respectively. The fact that the difference between them was very small indicated that the model was not overfitted. The maximum and minimum error was approximately 2% and the total MSE was 0.078%. Conclusions: The MLP model could help predict the alcohol concentration and to control the production process of makgeolli. In future research, the optimization of the production process will be studied based on the model.