• Bulletin of the Korean Chemical Society
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• 제24권10호
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• pp.1444-1448
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• 2003

The microsurface adsorption - spectral correction (MSASC) technique has been applied to the interaction of indigo carmine (IC) with cetyltrimethylammonium bromide (CTAB). The aggregation of IC on CTAB obeys Langmuir isothermal adsorption. The results show that both the monomer complex $IC{\cdot}CTAB$ and the micellar complex $(IC{\cdot}CTAB)_{78}$ were formed. The binding constant of the monomer complex was calculated to be $K_{IC{\cdot}CTAB}$ = 2.20 ${\times}10^5L{\cdot}mol^{-1}$, and the molar absorptivity of the micellar complex was calculated to be ${\varepsilon}_{(IC{\cdot}CTAB)78}\;^{560nm}$ = 8.58 ${\times}10^5L{\cdot}mol^{-1}{\cdot}cm^{-1}$. The aggregation was applied to the determination of cationic surfactant in wastewater.

• Bulletin of the Korean Chemical Society
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• 제25권9호
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• pp.1321-1325
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• 2004

Sodium dodecyl sulfate (SDS), an anionic surfactant, can strongly adsorb at the surface of a carbon paste electrode (CPE) via the hydrophobic interaction. In pH 3.0 $Na_2HPO_4$-citric acid buffer (Mcllvaine buffer) and in the presence of SDS, the cationic indole-3-acetic acid (IAA, $pK_a$ = 4.75) was highly accumulated at the CPE surface through the electrostatic interaction between the negative-charged head group of SDS and cationic IAA, compared with that in the absence of SDS. Hence, the oxidation peak current of IAA increases greatly and the oxidation peak potential shifts towards more negative direction. The experimental parameters, such as pH, varieties of surfactants, concentration of SDS, and scan rate were optimized for IAA determination. The oxidation peak current is proportional to the concentration of IAA over the range from $5\;{\times}\;10^{-8}$ mol/L to $2\;{\times}\;10^{-6}$ mol/L. The detection limit is $2\;{\times}\;10^{-8}$ mol/L after 3 min of accumulation. This new voltammetric method was successfully used to detect IAA in some plant leaves.

• Bulletin of the Korean Chemical Society
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• 제24권2호
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• pp.222-224
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• 2003

• Bulletin of the Korean Chemical Society
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• 제28권1호
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• pp.85-88
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• 2007

Ab initio periodic Hartree-Fock calculations with the full potential and minimum basis set are applied to interpretation of scanning tunneling microscope (STM) and atomic force microscope (AFM) images on 1TVTe2. Our results show that the simulated STM image shows asymmetry while the simulated AFM image shows the circular electron densities at the bright spots without asymmetry of electron density to agree with the experimental AFM image. The bright spots of both the STM and AFM images of VTe2 are associated with the surface Te atoms, while the patterns of bright spots of STM and AFM images are different.

• Bulletin of the Korean Chemical Society
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• 제28권10호
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• pp.1729-1734
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• 2007

The electrochemical behaviors of estrone in the presence of various surfactants were examined with great details. It is found that a cationic surfactant, cetyltrimethylammonium bromide (CTAB), obviously facilitates the electro-oxidation of estrone at carbon paste electrode (CPE) from the significant peak current enhancement and the negative shift of peak potential. Additionally, chronocoulometry and electrochemical impedance spectroscopy (EIS) were also used for further investigation of the electrode process of estrone, indicating that low concentration of CTAB exhibits excellent enhancement effects on the electrochemical oxidation of estrone, greatly enhances the diffusion coefficient and the electron transfer rate. Based on this, an electrochemical method was proposed for the determination of estrone. The oxidation peak current is proportional to the concentration of estrone in the ranges over 9.0 × 10?8 - 8.0 × 10?6 mol/L, and a low detection limit of 4.0 × 10?8 mol/L was obtained for 180s accumulation at open circuit (S/N = 3). Finally, this proposed method was demonstrated using estrone tablets with good satisfaction.

• 한국대기환경학회지
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• 제15권3호
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• pp.327-333
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• 1999

Determination of chloride ion in concentrated NaOH solution by capillary electrophoresis has been studied. The analysis was performed by indirect UV absorption detection using chromate buffer at 254nm. The matrix effect of the sample has been observed so that the sensitivity in strong NaOH solutaion has decreased up to 10% of that in distilled water. The pH effect of the sample on the sensitivity of CE peaks has been investigated. The method for increasing the sensitivity have been investigated and the optimum pH and concentration of the buffer were 7.5 and 10mM, respectively. A cationic surfactant cetyltrimethylammonium bromide(CTAB), was added to a buffer solution in order to reverse the electroosmotic flow(EOF) in the capillary. This results in a short analysis time and better peak shapes. Using this optimum condition, the determination of chloride ion in real environmental sample has been performed, which is captured in strong NaOH absorbent prepared for absorbing gas from chimney. The standard addition method has been applied for the quantitative analysis, and it was obtained the good reproducibility.

• Bulletin of the Korean Chemical Society
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• 제34권4호
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• pp.1065-1069
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• 2013

A highly sensitive electrochemical detection method for bisphenol A (BPA) has been developed by using multi-walled carbon nanotube (CNT)-doped titania-Nafion composite modified glassy carbon (GC) electrode. The CNT-titania-Nafion/GC electrode exhibited excellent electrocatalytic activity towards BPA. Therefore, the CNT-titania-Nafion/GC electrode showed improved voltammetric responses for BPA compared to that obtained with bare GC electrode. In addition, cetyltrimethylammonium bromide (CTAB), a cationic surfactant, was added into the BPA sample solution in order to accumulate BPA through hydrophobic interaction between CTAB and BPA. The CNT-titania-Nafion/GC electrode gave a linear response ($r^2$ = 0.999) for BPA from $1.0{\times}10^{-8}$ M to $5.0{\times}10^{-6}$ M with a detection limit of $9.0{\times}10^{-10}$ M (S/N = 3). The modified electrode showed good selectivity against interfering species and also exhibited good reproducibility. The present electrochemical sensor based on the CNT-titania-Nafion/GC electrode was applied to the determination of BPA in food package samples.

• 대한화학회지
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• 제37권5호
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• pp.496-502
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• 1993

Spectrophotometric Determination of Rare Earths by Ternary CompleMTB와 희토류 원소들 간에 이루어진 착물에 cetylpyridinium chloride(CPC), dodecyltrimethylammonium bromide(DTMAB), cetyltrimethylammonium bromide (CTMAB), Triton X-100 등의 계면활성제를 가하였을 때의 흡광도 변화로부터 이들 원소를 정량하는 방법과 조성비를 연구하였다. 양이온 계면활성제들인 CPC, DTMAB, CTMAB 등이 있을 때 MTB와 희토류 원소들간의 흡광도가 계면활성제들이 없을 때보다 더 컸다. 가장 큰 흡광도 증가는 CPC에서 얻어졌으므로 희토류 정량에는 이를 선택하였다. REE-MTB-CPC 삼성분 착물은 650nm에서 최대흡광도를 갖고 0~100 ng/ml 범위에서 Beer 법칙에 따르고 몰흡광계수는 $6.6{\sim}9.4{\times}10^4\;mol^{-1}l\;cm^{-1}$이다.

• 분석과학
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• 제7권3호
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• pp.277-284
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• 1994

Xylenol orange(XO)와 희토류 원소들간에 이루어진 착물에 cetylpyridium chloride (CPC), dodecyltrimethylammonium bromide(DTMAB), cetyltrimetylammonium bromide(CTMAB), Triton X-100 등의 계면활성제를 가했을 대의 흡광도 변화로부터 이들 원소를 정량하는 방법과 조성비를 연구하였다. 양이온성 계면활성제인 CTMAB가 있을 때 XO와 희토류 원소들간의 착물의 흡광도가 다른 계면활성제에서보다 더 컸다. 따라서 희토류 정량에는 이를 선택하였다. REE-XO-CTMAB 삼성분 착물은 618nm에서 최대 흡광도를 갖고 0~0.5ppm 범위에서 Beer 법칙에 따르고 몰흡광계수는 $1.5{\times}10^5mol^{-1}cm^{-1}l$이다.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2003년도 춘계학술발표논문집
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• pp.307-310
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• 2003

In order to analyze the concentration of cetylpyridinium chloride(CPC), a widely used cationic surfactant, we developed a simple and compact spectrometer, which consisted of a diode laser and a photodiode detector. Preliminary results are described here on the performances of the system in terms if the stability of output intensity, sensitivity, and reproducibility. Data on the comparisons of the system with the conventional UV-VIS spectrometer are also given. With the instrument, the concentration of CPC between 3${\times}$10$\^$-5/M and 1.1${\times}$ 10$\^$-4/M are calibrated as a correlation coefficient of 0.9635. The results shown here indicate a potential for developing a portable spectrometer useful for analyzing concentrations of CPC.