• Journal of the Society of Cosmetic Scientists of Korea
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• v.33 no.1 s.60
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• pp.11-15
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• 2007

Oxidation/reduction titrations are important quantitative procedures for many chemicals. Several widely used analytical methods for cosmetic ingredients are based on the redox reactions. In this article, we summarized basic theories of redox titration and applications. Determination of unsaturation properties based on iodine or bromine number, quantitation of hydrogen peroxide or peroxide materials in several cosmetic ingredients and measurement of titanium dioxide, widely used sunscreen agent, in cosmetics are discussed here.

• Analytical Science and Technology
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• v.12 no.4
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• pp.290-298
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• 1999

A study on the application of impedance phase angle for redox titration, acid-base titration, chelate titration and precipitation titration has been carried out. A constant alternating current was passed between two platinum electrodes. One of them was a polarizable micro-electrode of $0.1cm^2$ or $0.026cm^2$ surface area and the other a non-polarizable large electrode of $1cm^2$ surface area dipped in the solution to be titrated. The impedance and the phase angle of the titration cell were measured with lock-in amplifier to obtain well behaved titration curve respectively. In titration of oxalic acid vs. potassium permanganate, the end-point was obtained successfully from the phase angle titration curve. In this experiment, the concentration of 0.0005 M to 0.05 M, the current of $50{\mu}A$ and the frequency of near 50 Hz were used. In titration of phosphoric acid vs. sodium hydroxide, the first end-point was obtained successfully on the optimum experimental condition of 0.001 M concentration, $50{\mu}A$ current and 25~97 Hz frequency. However, the end-point in titration of cupric sulfate vs. disodium-EDTA couldn't be obtained clearly. The end-point was obtained with the out-of-phase impedance curve on the experimental condition of 0.01 M concentration, $100{\mu}A$ current, 5~35 Hz frequency range. In titration of sodium chloride vs. silver nitrate, the end-point was obtained successfully on the experimental condition of 0.1 M concentration, $100{\mu}A$ current and 5~47 Hz frequency range. This study showed that the impedance phase angle was applicable for the detection of the end-points in redox titration curve, acid-base titration curve, chelate titration curve and precipitation titration curve.

• Korean Journal of Food Science and Technology
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• v.36 no.6
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• pp.885-892
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• 2004

Peroxide values (PV) of fat from fallow up formula were determined using redox-potentiometric titration method and standard method, which is based on KI oxidation by hydroperoxides and volumetric titration of liberated iodine, and their uncertainties were compared. Uncertainty sources in measurement, such as sample weight, sodium thiosulfate concentration, and titer, were identified and used as parameters for combined standard uncertainty based on Guide to the expression of uncertainty in measurement and Draft EURACHEM/CITAC Guide. Analytical results and combined standard uncertainties of peroxide values (PV) determined by standard burette and potentiometric titrations were $2.05{\pm}0.17\;and\;1.96{\pm}0.07\;meq/kg$, respectively, suggesting potentiometric titration method is suitable for determining PV of fat with low PV, because uncertainty of PV determination obtained by potentiometric titration was lower than that obtained by burette titration.

• Feed Journal
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• v.2 no.4
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• pp.72-74
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• 2004

농림부는 지난달 축산법 제 20조의 5 및 동법 시행규칙 제25조의 2제3호의 규정에 의하여 가축사육시설 단위면적당 적정 가축사육기준과 축산법 제2조1호 및 동법 시행 규칙 제2조제4호의 규정에 의하여 사육하는 동물중 가축의 범위에 해당하는 기타 동물을 고시했다. 다음은 고시된 내용을 정리한 것이다.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11c
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• pp.1707-1710
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• 2003

최근에 전자상거래 시스템에 다양한 에이전트를 적용하여 전자상거래를 보다 활성화시키고 효율적으로 운영하려는 경향이 늘어나고 있다. 그러나 현재까지의 에이전트 연구는 판매자의 실제 이익보다는 구매자의 선호도에 따른 물품을 추천하는데 그 기능이 제한되어 있으며, 한 단계 더 나아가 가격과 이윤 문제를 다룬 연구가 있어도, 제시한 가격이 판매자의 이윤에 어느 정도 영향을 미치는지 파악하기 어려운 문제가 있었다. 따라서, 본 논문에서는 이러한 문제를 해결하기 위하여 원가 회계 이론에 기반한 여러 가지 원가 산정법 중 고저점법과 학습 곡선법의 비교 분석을 통하여 원가를 보다 정확히 산정하고, 판매자는 이를 반영하여 입찰가를 결정함으로써 적정 이윤을 얻을 수 있도록 한다. 또한, 판매자가 이윤을 높일수록 경매 유찰 가능성이 커지므로, 과거 낙찰 기록 데이터의 분석을 통해 판매자가 적정 낙찰율을 확보할 수 있도록 한다. 이를 위해 본 논문에서는 각 원가 산정법을 적용한 에이전트 성능 실험을 통해 적정 이윤을 보장하면서도 낙찰율을 향상시킬 수 있음을 연구한다.

• Journal of the Korean Chemical Society
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• v.22 no.3
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• pp.128-132
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• 1978

The potentiometric end-point of redox titrations determined by nulling the second derivative of the titration curve by numerical differentiation method is analyzed by using an electronic digital computer. The error involved in the method is shown to be dependent on the location of the equivalence point in the titrant addition increment that encompasses the latter. The error increases as the equivalence point moves away from the mid-point of the increment toward a maximum value that is as great as a half of the increment. Therefore, when the numerical differentiation method is used to null the second derivative, the end-point should be compared with the steepest point of the titration curve or diluted titrant should be used in the vicinity of the end-point.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.3
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• pp.160-171
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• 1993

Surface charge characteristics of Ultisol(Luisiana soil from Philippines), Alfisol(Maahas soil from Philippines), and Inceptisol(Yongii soil from Korea) were studied by way of potentiometric titration, backtitration technique, and ion adsorption method(or CEC - AEC method). The PZNC(point of zero net charge) values determined by ion adsorption method were much lower than the natural pHs in all soils, indicating that all soil samples bore net negative surface charge. The PZSE (point of zero salt effect) values determined by potentiometric titration and backtitration technique were identical in Luisiana and Yongii soils but not in Maaghas soil. All soils showed higher PZSE values than PZNC values probably due to the influence of permanent negative charge. The permanent charge calculated by the theory of Uehara and Gillman (1980) occupied quite low portion of the CEC measured at pH 7 in all soils. Backtitration technique corrected errors of potentiometric titration at extreme pH. However, it still overestimate the surface charge compared with ion adsorption method. Therefore, the ion adsorption method was recommanded for the surface charge measurement of the usual soils which have high negative charge components.

• Journal of the Korean Chemical Society
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• v.54 no.5
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• pp.497-499
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• 2010

• Applied Chemistry for Engineering
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• v.34 no.4
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• pp.450-454
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• 2023

Chloride ions in the alloy powder used as flux in Flux Cored Arc Welding (FCAW) can cause pores on the bead surface of the welding metal to cause defects, or chloride remaining in the alloy powder can cause corrosion of the metal. Combustion-ion chromatography is mainly used to quantify the chloride ions in alloy powder, but there is a limitation in that the equipment is expensive and requires a high degree of expertise. Therefore, this study aims to find an easy and accurate quantification method in the field by comparing combustion-ion chromatography (C-IC), which is mainly used for chloride ion quantification of alloy powder, X-ray fluorescence analysis (XRF), and potentiometric titration. In this article, magnesium-aluminum alloy powder is applied to the quantification of chloride ions because it is most commonly used as flux. This study confirmed that potentiometric titration can be applied to the quantification of chloride ions in the alloy powder in the industry field.

• Korean Journal of Food Science and Technology
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• v.37 no.3
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• pp.352-359
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• 2005

Uncertainty involved during determination of vitamin C content in infant formula was quantified by indophenol titration method. Uncertainty sources in measurand, such as purity, weight, final volume of standard, volume of standard solution used for titration, sample weight, final volume of sample, extraction solution used for titration, titration of extraction solution and standard solution by indophenol solution were identified and used as parameters for combined standard uncertainty based on Guide to the expression of uncertainty in measurement (GUM) and Draft EURACHEM/CITAC Guide. Uncertainty parameters of each source in measurand were identified as resolution, reproducibility and stability of chemical balance, standard material purity, repeatability, reproducibility, end point of titration, 1 mL pipet, 5 mL autopipet, and 100 mL mass flask. Each uncertainty component was evaluated by types A and B and included to calculate combined uncertainty. Analytical test result for traceability under laboratorial conditions using Certified Reference Material (CRM) test was certified as $108.4{\pm}1.7mg/100g$, which was within CRM certification range of $114.6{\pm}6.6mg/100g$. Uncertainty test result of vitamin C content of 5 g sampling was $56.7{\pm}2.44mg/100g$. Uncertainty could be reduced by identification of uncertainty sources and components related with vitamin C determination by indophenol titration method and by decreasing uncertainty sources and components.