• 분석과학
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• 제32권3호
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• pp.77-87
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• 2019

High viscosity carbon black dispersions are used in various industrial fields such as color cosmetics, rubber, tire, plastic and color filter ink. However, carbon black particles are unstable to heat due to inherent characteristics, and it is very difficult to keep the quality of the product constant due to agglomeration of particles. In general, particle size analysis is performed by dynamic light scattering (DLS) during the dispersion process in order to select the optimum dispersant in the carbon black dispersion process. However, the existing low viscosity analysis provides reproducible particle distribution analysis results, but it is difficult to select the optimum dispersant because it is difficult to analyze the reproducible particle distribution at high viscosity. In this study, dynamic light scattering (DLS) and asymmetrical flow field-flow fractionation (AsFlFFF) analysis methods were compared for reproducible particle size analysis of high viscosity carbon black. First, the stability of carbon black dispersion was investigated by particle size analysis by DLS and AsFlFFF according to milling time, and the validity of analytical method for the selection of the optimum dispersant useful for carbon black dispersion was confirmed. The correlation between color and particle size of particles in high viscosity carbon black dispersion was investigated by using colorimeter. The particle size distribution from AsFlFFF was consistent with the colorimetric results. As a result, the correlation between AsFlFFF and colorimetric results confirmed the possibility of a strong analytical method for determining the appropriate dispersant and milling time in high viscosity carbon black dispersions. In addition, for nanoparticles with relatively broad particle size distributions such as carbon black, AsFlFFF has been found to provide a more accurate particle size distribution than DLS. This is because AsFlFFF, unlike DLS, can analyze each fraction by separating particles by size.

• Bulletin of the Korean Chemical Society
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• 제32권4호
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• pp.1315-1320
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• 2011

Whey protein (WP) is a mixture of proteins, and is of high nutritional values. WP has become an important source of functional ingredients in various health-promoting foods. In this study, size-exclusion chromatography (SEC) and asymmetrical flow field-flow fractionation (AsFlFFF) were used for separation and analysis of whey proteins. It was found that a lab-prepared WP from raw milk is mostly of ${\beta}$-lactoglobulin with small amount of higher molecular weight components, while a commercial whey protein isolate (WPI) powder contains relatively larger amount of components other than ${\beta}$-lactoglobulin, including IgG and protein aggregates. Results suggest that AsFlFFF provides higher resolution for the major whey proteins than SEC in their normal operation conditions. AsFlFFF could differentiate the BSA and Albumin, despite a small difference in their molecular weights, and also was able to separate much smaller amount of aggregates from monomers. It is noted that SEC was able to show the presence of low molecular weight components other than the major whey proteins in the WP samples, which AsFlFFF could not show, probably due to the partial loss of those low molecular weight species through the membrane.

• 분석과학
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• 제32권5호
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• pp.173-184
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• 2019

As the size of semiconductors becomes smaller, it is necessary to perform high precision polishing of nanoscale. Ceria, which is generally used as an abrasive, is widely used because of its uniform quality, but its stability is not high because it has a high molecular weight and causes agglomeration and rapid precipitation. Such agglomeration and precipitation causes scratches in the polishing process. Therefore, it is important to accurately analyze the size distribution of ceria particles. In this study, a study was conducted to select dispersants useful for preventing coagulation and sedimentation of ceria. First, a dispersant was synthesized and a ceria slurry was prepared. The defoamer selection experiment was performed in order to remove the air bubbles which may occur in the production of ceria slurry. Dynamic light scattering (DLS) and asymmetrical flow field-flow fractionation (AsFlFFF) were used to determine the size distribution of ceria particles in the slurry. AsFlFFF is a technique for separating nanoparticles based on sequential elution of samples as in chromatography, and is a useful technique for determining the particle size distribution of nanoparticle samples. AsFlFFF was able to confirm the presence of a little quantities of large particles in the vicinity of 300 nm, which DLS can not detect, besides the main distribution in the range of 60-80 nm. AsFlFFF showed better accuracy and precision than DLS for particle size analysis of a little quantities of large particles such as ceria slurry treated in this study.

• Bulletin of the Korean Chemical Society
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• 제27권9호
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• pp.1433-1438
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• 2006

An AsFlFFF channel was designed and built, and then tested for analysis of pullulans and proteins. Pullulans and proteins having various nominal molecular weights were injected at various conditions of the cross-flow rate ($F_c$) and the channel-out flow rate ($F_{out}$). The retention (measured by the retention ratio R) and the zone broadening (measured by the plate height H) were measured, and then compared with theory. When the incoming flow rate, $f_{in}$ (and thus $F_{out}$) was varied with $F_c$ fixed at 2.5 mL/min, the plate height measured for the pullulan with nominal molecular weight (M) of about 100,000 showed the trend expected by the longitudinal diffusion theory (H decreases with increasing flow rate). In contrast, when $F_{out}$ was varied with the flow rate ratio, $F_c/F_{out}$, fixed constant at 5, the plate height measured for the same sample showed the trend expected from the non-equilibrium theory (H increases with increasing flow rate). Calibration plots (log D vs. log M) obtained with pullulans and proteins were not coincide, probably due to the difference in molecular conformation, suggesting the analysis of pullulans and proteins using AsFlFFF requires independent calibration. It was found that the linearity of the protein-calibration plot was improved by using a buffer solution as the carrier.

• 한국응용과학기술학회지
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• 제34권2호
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• pp.357-366
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• 2017

천연색소는 색을 발현할 수 있는 물질로서 식품, 화장품, 의약품 등에 사용된다. 천연색소는 동 식물에서 추출하여 만들기 때문에 크기가 균일하지 않으며 특히 적색색소의 경우, 다른 색의 색소에 비해 친유성이 강해 수용액 상태에서 쉽게 응집이 되는 경향이 있다. 또한 응집에 의한 크기변화로 인해 색의 재현이 어려운 문제점이 있다. 적색색소로 기존에 사용했던 동물성 색소인 코치닐 추출 색소는 알레르기를 유발하고 식용으로서의 거부감이 있는 등의 문제점으로 인하여 사용이 기피되는 추세이다. 본 연구에서는 적색의 식물성 색소인 라이코펜 추출물과 치자황색소를 사용하였고 Ball-milling을 이용하여 색소의 크기를 균일하게 만든 후 Asymmetrical flow field-flow fractionation(AsFlFFF), Dynamic light scattering(DLS)를 이용하여 크기를 분석하고 색차계를 이용하여 색을 확인하는 연구를 진행하였다. 실험결과 milling 전에는 색소 입자의 크기가 크고 크기분포가 넓었으나, milling 후에는 크기가 감소하고 크기분포가 좁아짐을 확인하였다. 색차계 측정 결과, milling 시간이 증가함에 따라 밝기, 적색도, 황색도가 높아져서 밝은 적색을 나타내었다.

• 분석과학
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• 제30권4호
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• pp.159-166
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• 2017

Exposure to UV light, i.e., UV-A (320-400 nm) or UV-B (290-320 nm) radiation, can cause skin cancer. Titanium dioxide ($TiO_2$) effectively disperses UV light. Therefore, it is used as a physical UV filter in many UV light blockers. Usually, the $TiO_2$ content in commercialized UV blockers is 25 % at most. To block UV-B, a chemical UV blocker, octyl-methoxy cinnamate (OMC) is used. OMC is commonly used in combination with $TiO_2$. In this study, $TiO_2$ and OMC were mixed in different proportions to produce UV blockers with different compositions. Also the changes in the sun protection factor (SPF) based on the composition and $TiO_2$ particle sizes were investigated. In order to analyze the $TiO_2$ particle size, dynamic light scattering (DLS) and asymmetrical flow field-flow fractionation (AsFlFFF) were used. The results showed that the SPF was influenced by the proportion of $TiO_2$ and OMC, where the proportion of $TiO_2$ induced a more significant influence. In addition, changes in the $TiO_2$ particle size based on the proportion of OMC were observed.