• Journal of Environmental Science International
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• v.14 no.6
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• pp.525-532
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• 2005

Polyelectrolyte titration, which was called colloid titration is based on the stoichiometric reaction between oppositely charged polyelectrolytes, This can be used, for instance, to determine the charge density of a cationic polyelectrolyte, using an anionic polyelectrolyte of known charge density, such as potassium polyvinyl sulfate (PPVS). The technique requires a suitable method of end-point detection and there are several possibilities. In this work, two methods have been investigated: visual titrimetry based on the color change of a cationic dye (o-toluidine blue, o-Tb) and spectrophotometry based on the absorbance change corresponding to the color change of the same dye. These have been applied to several cationic polyelectrolytes with different charge density and molecular weight. In all cases, the cationic charge was due to quaternary nitrogen groups. In the case of cationic dye, it was shown that the sharpness depends on the charge density of cationic polyelectrolyte. With the polyelectrolytes of lower charge density, the binding to PPVS is weaker and binding of the dye to PPVS can occur before all of the polyelectrolyte charge has been neutralized. However, by carrying out titrations at several polyelectrolyte concentrations, good linear relationships were found, from which reliable charge density values could be derived. Effects of pH and ionic strength were also briefly investigated. For cationic polyelectrolytes (copolymers of acrylamide and dimethylaminoethy] acrylate), there was some loss of charge at higher pH values, probably as a result of hydrolysis. Increasing ionic strength causes a less distinct color change of o-Tb, as a result of weaker electrostatic interactions.

• Journal of the Korean Society of Food Culture
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• v.34 no.6
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• pp.761-770
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• 2019

Two experiments were conducted to determine how much sodium in food could be detected using a salinity meter. First, the salinity of mixed solutions of 0 to 6% sugar, 0 to 5% oil, and 0 to 6.4% MSG in a 1% NaCl solution was measured using a salinity meter and a Mohr titration method, and the results were compared with the calculated sodium expectations. As a result, the sodium contents of the sugar solutions and MSG solutions measured using a salinity meter were lower than the expected concentrations at 2% or more and 0.8% or more, respectively (p<0.05). The salinity of the 18 HMR products was measured in the same way, and the results were then compared with the sodium contents of the nutrition facts. The average sodium content of all products measured using the salinity meter and Mohr method was 1.12 times and 1.06 times the sodium content of the nutrition facts, respectively. On the other hand, the differences between the products were significant. The correlation coefficients between the nutrition facts and salinity meter, the nutrition facts and the Mohr method, and the salinity meter and Mohr method were 0.885, 0.920, and 0.950, respectively (p<0.01).

• Analytical Science and Technology
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• v.33 no.6
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• pp.252-261
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• 2020

Currently, the potentiometric titration and the high pressure liquid chromatography (HPLC) method were utilized in Korean Pharmacopoeia XII (KP XII) as well as other pharmacopoeias (USP, EP, BP) for determination of loperamide hydrochloride in raw materials and capsules, respectively. The research objective is to overcome the remaining drawbacks from current methods such as solubility of mobile phase (KP XII), less scientific approach (USP 43) or using paired-ion chromatography reagent which shows some limitations (BP2017 and other formulation monographs). The proposed method was optimized by Design of Experiment (DoE) tool to obtain the satisfied method for determination of loperamide hydrochloride. The optimal condition was performed on the common C18 column (150 mm × 4.6 mm; 5 ㎛) using isocratic elution with the mobile phase containing 40 mM of potassium phosphate monobasic (pH 3.0) and acetonitrile (56:44), at a flow rate of 0.7 mL/min. The optimized method was validated and met the requirements of the International Conference on Harmonization. The developed method was applied to determine loperamide hydrochloride in capsules and can be used to update the current monograph in KP XII.

• Analytical Science and Technology
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• v.30 no.3
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• pp.154-158
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• 2017

The Korean Pharmacopoeia (KP XI), British Pharmacopoeia (BP 2013) and Japanese Pharmacopoeia contain monographs for the quality control of raw fusidate sodium and its formulations using high performance liquid chromatography (HPLC). However, the assay method for the determination of fusidate sodium in commercial tablets is titration which is less specific than HPLC. In this study, we present an alternative HPLC method for quantitation of fusidate sodium in tablets. Method validation was performed to determine linearity, precision, accuracy, system suitability, and robustness. The linearity of calibration curves in the desired concentration range was high ($r^2=0.9999$), while the RSDs for intra- and inter-day precision were 0.25-0.37 % and 0.11-0.60 %, respectively. Accuracies ranged from 99.46-100.85 %. Since the system suitability, intermediate-precision and robustness of the assay were satisfactory, this method will be a valuable addition to the Korean Pharmacopoeia (KP XI).

• Journal of Life Science
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• v.22 no.6
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• pp.703-712
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• 2012

Adeno-associated virus (AAV) has been considered to be a very safe and efficient gene delivery system. However, the major obstacles to therapeutic usage of AAV have been to achieve highly efficient and reproducible production processes, and also to develop a reliable quantifying method of various serotypes with a simple protocol. We compared the efficiency of the conventional production protocol of AAV2 and adenovirus (Ad) co-infection to that of a new method containing AAV2 infection followed by pHelper transfection. We tested HEK293 and 293T, and further examined the time-dependent changes of AAV2 production. The new method of AAV2 and pHelper DNA gave about ten times higher production efficiency than that of the conventional protocol. The highest production efficiency in 293T was achieved as $1.61{\times}10^5$ virus genomes (v.g.)/cell by the new method of 10 MOI of AAV2 infection and 5 days post-infection. This protocol of the highest efficiency was then applied to produce various AAV serotypes and showed the efficiencies higher than $10^5$ v.g./cell. Next, we designed the universal PCR primers of highly conserved regions for various AAV serotypes to develop a simple and reliable titration method. The universal primers could amplify all the tested AAV serotypes with similar sensitivities by ten molecular copies. Therefore, this pair of universal primers can be further utilized to detect AAV contaminants in therapeutic adenoviral vectors.

• Korean Journal of Veterinary Research
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• v.35 no.1
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• pp.131-135
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• 1995

This study was performed to develop immnoassay method of detecting the residual tylosin and to investigate the residues using HPLC(high performance liquid chromatography) in animal products. Obtained results are the followings: 1. To develop immunoassay method, the conjugation of activated tylosin tartarate ester derivatives and BSA (bovine serum albumin) was certified at the 290nm of maximal absorbance which tylosin tartrate have. 2. The titration of anti-serum produced from rabbit immunized with the conjugator as an immunogen was too low to analyze the tylosin. 3. The residual tylosin can be detected by 0.2 ppm using HPLC. 4. Recovery of tylosin from spiked pork samples measured using HPLC was $87.4{\pm}4.0%$. 5. When the levels of tylosin residues in swine liver and kindney were measured on HPLC. The level was over the maximum tolerance level in one out of ten samples of each organ.

• Korean Journal of Food Science and Technology
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• v.34 no.3
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• pp.361-364
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• 2002

This study was performed to establish a simple and accurate method for the determination of oxygen that is a processing aid in various beverage. The quantitative determination of dissolved oxygen (DO) contents in 30 cases of samples were performed by traditional titration method and polarography. As a result of the study, the analysis of DO contents in fruit-extract beverages containing oxygen by titration method was time consuming and large sample volumes were needed. Besides, serious interferences with compounds such as hydroxylamine and nitric oxide were observed, leading to false response. Although the polarography is easily affected by $H_2S$, proteins, and various organic compounds, it is a simple and practical method that provides inexpensive and relatively rapid analysis. The polarography is best suited to the routine determination of DO in a large number of samples and it is expected that the polarography can directly be applied to the quality control of the beverages containing added oxygen. The analysis results of DO contents in various fruit-extract beverages with oxygen and without oxygen were as follows: 23.10 ppm to 32.60 ppm for various frutis extract beverages with oxygen, 0.70 pp to 2.54 ppm for mixed beverages without oxygen, 7.63 ppm to 8.28 ppm for drinking water.

• Laboratory Medicine Online
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• v.1 no.1
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• pp.57-63
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• 2011

Background: ABO antibody titration is useful for the evaluation of ABO-incompatible bone marrow or solid organ transplantations, yet the results quite vary between different test methods used. We compared the results of microcolumn agglutination and tube methods. Methods: Anti-A and anti-B isoagglutionin titers were determined in 63 healthy individuals (23 O, 20 A, and 20 B blood groups) using 4 different methods: immediate spin tube (tube), microcolumn agglutination without anti-human globulin (AHG) (CAT), tube with AHG (tube-AHG) and microcolumn agglutination with AHG (CAT-AHG). Results: The median (range) titers of anti-A and anti-B in group O individuals by tube, CAT, tube-AHG, and CAT-AHG methods were 64 (8-512), 64 (8-512), 128 (8-2,048), and 128 (16-2,048); 64 (16-128), 128 (16-256), 128 (16-512), and 256 (16-512), respectively. The median (range) titers of anti-A in group B and anti-B in group A individuals by the four methods were 64 (16-128), 128 (8-128), 128 (8-256), and 256 (8-256); 64 (8-128), 64 (8-128), 32 (8-128), and 64 (8-256), respectively. The isoagglutinin titer measured by CAT-AHGmethod was the highest. The titers measured by CAT and CAT-AHG methods were 0-1 titer higher than those by tube and tube-AHG methods, respectively. Whatever method was used, the isoagglutinin titers were higher in women than in men. Conclusions: CAT-AHG was the most sensitive method among the four methods tested. Since AHG titer values are critical for the clinical management and CAT has less manual procedures than tube method, CAT-AHG method could be used for the standardization of ABO antibody titration in different institutions.

• Bulletin of the Korean Chemical Society
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• v.31 no.9
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• pp.2618-2626
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• 2010

In this paper poly (4-methyl vinylpyridinium hydroxide)/SBA-15 composite was prepared as a highly efficient heterogeneous basic catalyst by in situ polymerization method for the first time. It was characterized by XRD, FT-IR, BET, TGA, SEM and back titration using NaOH. This catalyst exhibited the excellent catalytic activities for the Knoevenagel condensation of various aldehydes with ethyl cyanoacetate. Over this catalyst, ${\alpha},{\beta}$-unsaturated carbonyl compounds were obtained in the reasonable yield at $95^{\circ}C$ in 10 - 30 min in $H_2O$ as a solvent with a 100% selectivity to the condensation products. Catalyst could be easily recycled after the reaction and it could be reused without the significant loss of activity/selectivity performance. No by-product formation, high yields, short reaction times, mild reaction conditions and operational simplicity with reusability of the catalyst were the salient features of the present synthetic protocol. Presence of $H_2O$ as a solvent was also recognized as a "green method".

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.26-32
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• 2003

Rice is one of the most important cereals in the world. Japanese people use about 9 million tons of rice per you. We use rice for cooked rice as staple foods and for processing, such as rice wine (sake), rice crackers and miso fermentation, etc. Palatability, eating quality, of rice is evaluated by the sensory test and various kinds of physicochemical measurements. Japanese National Food Agency started the storage of 1.5 million tones of rice in 1996. We carried out the storage test using high quality rices since 1995 until 1996. As indices for the quality deteriorations of rice grains during the storage, germination ratio, enzyme activities, fat acidity, physical properties of cooked rice were clarified to be useful. We applied colorimetric method for the measurements of fat acidities in the place of titration method. Processing suitabilities of rice differ depending on the products. Low amylose rice is more suitable for soft rice crackers and high amylose rice is preferred more for rice noodle. Pre-cooked rice products, such as frozen cooked rice, retort-pouched rice and aseptic rice, are increasing recently in Japan. In addition to above-mentioned physico-chemical tests, NIR spectroscopy,“Midometer”and“Taste sensor”are novel and useful to evaluate eating quality and processing suitabolities. Recently, rice wholesalers and retailers have been obligated to display the name of cultivar, location of cultivation and the year of production of rice grains which they sell by the Japanese Agricultural Standard Law (JAS). In order to detect the dishonest labeling of rice cultivars, we developed new cultivar identification method based on DNA polymorphism.