• Analytical Science and Technology
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• v.9 no.2
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• pp.139-144
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• 1996

The spectrophotometric determination method of scandium with eriochrome cyanine R(ECR) and the composition ratio of the complex were investigated in the presence of surfactants. The absorbance increase and red shift of maximum adsorption wavelength of Sc(III)-ECR complex were observed in cetyltrimethylammonium bromide (CTMAB), but those changes were not observed in the sodium dodecyl sulfate(SDS) and Triton X-100. A volume of 5ml of $1{\times}10^{-3}M$ ECR and 10ml of $2{\times}10^{-4}M$ CTMAB are necessary for the determination of $1{\times}10^{-7}{\sim}3.0{\times}10^{-6}M$ Sc(III) at pH 6.5. The apparent molar absorption coefficient of the Sc(III)-ECR-CTMAB, temary complex at 610nm is $5.6{\times}10^5mol^{-1}cm^{-1}L$ and its detection limit is $1.0{\times}10^{-7}M$. The binary complex composition of Sc(III)-ECR is 1:2 and the ternary complex composition of Sc(III)-ECR-CTMAB is 1:3:1.

• Analytical Science and Technology
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• v.7 no.3
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• pp.277-284
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• 1994

The spectrophotometric determination of rare earth elements with XO was investigated in the presence of cetylpyridium chloride(CPC), dodecyltrimethylammonium bromide(DTMAB), cetyltrimetylammonium bromide (CTMAB), Triton X-100 at pH 6.2. The complex between XO and rare earth elements in the presence of cationic surfactants was very stable and more sensitive than in the absence of surfactants. The largest absorbance increase was provided by CTMAB, which was therefore chosen for determination of rare earth elements. REE-XO-CTMAB complex has absorption maxima at 618nm and obeys the Beer's law in the range of 0~0.5 ppm. Molar absorptivity was $1.5{\times}10^5mol^{-1}cm^{-1}l$.

• Applied Chemistry for Engineering
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• v.2 no.3
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• pp.229-237
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• 1991

Vinylester was syntheszed in the presence of amine and metal catalysts, such as triethylamine(TEA), triethylbenzyl ammonium chloride (TEBAC), cetyltrimethyl ammonium bromide (CTMAB), chromium acety] acetate (CAA), and triphenylantimony (TPA). Apropriate use of amine and organometal catalysts were 1.7~2.2 % (Wt. %), 2.5~3.1 % (Wt %) of charged methacrylic acid (MAA) in respect of reactivity, gel-time, and storage stability. The Order of reactivity was TEA>TEBAC>CTMAB>CAA>TPA. Temperature independence of catalyst showed more large deviation above $110^{\circ}C$. Storage stability could be improved without delay of gel-time by adding TPA in 2.0 % (Wt %) of charged MAA after synthesis.

• Bulletin of the Korean Chemical Society
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• v.20 no.12
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• pp.1409-1412
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• 1999

The spectrophotometric determination method of scandium with eriochrome cyanine R (ECR) and the composition ratio of the complex were investigated in the presence of surfactants. A volume of 5 mL of 1.0×$10^{-3}$ M ECR and 10 mL of 2.0×$10^{-4}$ M CTMAB are necessary for the determination of 1.0×$10 ^{-7}$ ~ 3.0×$10^{-6}$ M Sc(III) at pH 6.5. The apparent molar absorption coefficient of the Sc(III)-ECR-CTMAB, ternary complex at 610 nm is 5.6×$10^5$ $mol^{-1}cm{-1}$L and its detection limit is 1.0×$10^{-7}$ M. Separation studies were conducted by the column method. The effect of pH, elution solution and the influence of rare earth elements as interferents was discussed. Their separation was carried out in 0.1 M HCl-50% methanol solution and 1.0 M HCl media. The method was applied for the determination of Sc(III) in monazite.

• Journal of the Korean Chemical Society
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• v.37 no.5
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• pp.496-502
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• 1993

Spectrophotometric determination of rare earth elements with MTB and the composition ratio were investigated in the presence of surfactants of cetylpyridinium chloride (CPC), Triton X-100, dodecyltrimethylammonium bromide (DTMAB) and cetyltrimethylammonium bromide (CTMAB) at pH 6.5. The colour development between MTB and rare earths in the presence of cationic surfactants was very stable and more sensitive than that in the absence of surfactants. The largest absorbance increase was provided by CPC, which was therefore chosen for determination of rare earth elements. REE-MTB-CPC complex has absorption maxima at 650 nm and obeys the Beer's law in the range of 0∼100 ng/ml. Molar absorptivity is $6.6{\sim}9.4{\times}10^4\;mol^{-1}l\;cm^{-1}$.

• Journal of the Korean Chemical Society
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• v.33 no.6
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• pp.651-656
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• 1989

The catalytic effects of several phase-transfer catalysts (PTC) on the liquid-liquid heterogeneous nucleophilic displacement reaction of thiocyanate on benzyl chloride have been determined. Reactions followed a pseudo-first order dependency on the benzyl chloride concentration and the observed rate constant $(k_{obsd})$ were linearly related to the concentration of catalyst and varied with variables such as reaction temperature and solvent. The sequences of catalytic activity of the displacement were $NH_4Cl$ < BTMAC < 18-crown-6 < BTEAC < PEG < TBAC < CTMAB. Enthalpies and entropies of activation associated with the displacement were 15∼20 Kcal$mo^{l-1}$, -12∼-29 eu. respectively and the reaction occurs in the interphase comprising of microemulsion.

• Applied Chemistry for Engineering
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• v.1 no.1
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• pp.63-72
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• 1990

Surface of crystalline silica was sequentially reacted with silane(A 187), liquid rubber(CTBNx8) and vinyl monomer(AA, MMA, 2-HEA, GMA) in existance of amines(TEA, CTMAB, BETAC) or peroxide(BPO). By mixing it with epoxy resin at a ratio 0~36%(volume %) of total component, liquid properties of mixtures was investigated experimentally. i) Coating ratio depended on quantity and sorts of catalyst. ii) Total coating of 2.5~5.8% was attained by using 0.1~2.0% of catalyst. iii) Treated surfaces represented each different features in according to sorts of treatment. iv) Silane/rubber or silane/rubber/vinyl represented lower viscosity and settling than non-treated or silane-treated.

• Bulletin of the Korean Chemical Society
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• v.25 no.2
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• pp.263-266
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• 2004

A sensitive, selective and rapid method has been developed for the determination ${\mu}$g/L level of vanadium ion based on the rapid reaction of vanadium(V) with 2-(2-quinolylazo)-5-diethylaminophenol (QADEAP) and the solid phase extraction of the colored chelate with $C_{18}$ cartridge. The QADEAP reacts with V(V) in the presence of citric acid-sodium hydroxide buffer solution (pH = 3.5) and cetyl trimethylammonium bromide (CTMAB) medium to form a violet chelate of a molar ratio 1 : 2 (V(V) to QADEAP). This chelate was enriched by solid phase extraction with $C_{18}$cartridge and the enrichment factor of 50 was obtained by elution of the chelates from the cartridge with ethanol. The molar absorptivity of the chelate is $1.28 {\times}10^5L\;mol^{-1}cm^{-1}$ at 590 nm in the measured solution. Beer's law is obeyed in the range of 0.01-0.6 ${\mu}$g/mL. The detection limit is 0.04 ${\mu}$g/L in the original samples. This method was applied to the determination of vanadium(V) in water and biological samples with good results.