• Journal of the Korean Chemical Society
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• v.7 no.1
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• pp.29-33
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• 1963

A new method determining the micro amount of cupferron spectrophotometrically was investigated and was considered on the various factors which affect on the method. The method was as follows; ferric alum solution was added in a suitably acidified solution of cupferron. After the precipitates of Fe(Ⅲ)-cupferrate were formed, they were extracted with chloroform and the absorbancy of the organic phase was measured by spectrophotometer, Beckmann Model B (1cm quartz cell). The stable maximum wavelength was 325 $m{\mu}$ at 3.0 to 5.6 of the optimum pH and it obeyed on Boer's law in the range of 5.76 ${\gamma}/ml$ to 74.80 ${\gamma}/ml$ of cupferron. The maximum wavelength was independent on pH, concentration of cupferron and of ferric alum. The absorbancy at 325 $m{\mu}$ was not affected by $SO_4^{--}$ and Ac, but was varied by $Cl^-$ and $NO_3^-$. Sulfuric acid and acetate buffer are preferred to the acid and buffer solution adjusting the pH. At higher acidity, however, the absorbancy was somewhat lowered because of the decomposition of cupferron, and at too high concentration of ferric alum, it was also decreased because of the difficulty in the extraction. By this method, it was able to determine cupferron quantitatively in the percent error of 1.18.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06a
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• pp.137-140
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• 2006

This paper describes a technique combining chemometrics with UV spectroscopy for the determination of the concentra tions of two tissue additives (i.e., wet strength and softening agents) in a cellulose fiber containing solution. In single as ent solutions, the concentration of the additive can be measured by UV spectroscopy at the wavelength where the species having absorption. For a binary (i.e., containing two additives) solution system, the spectral characterization is very complicated. However, if aided by a chemometrical calibration technique, each additive in the binary solution can be quantified simultaneously. The present method is very rapid and simple, it can easily perform a continuous measurement in the changes in the additives' concentration after fiber addition, and therefore this becomes a valuable tool for the adsorption kinetics study of chemical additives onto the cellulose fibers. The time-dependent adsorption behaviors of the wet-strength, softening agent, and their both on fiber were also presented.

• YAKHAK HOEJI
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• v.18 no.2
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• pp.133-144
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• 1974

The metal indicator, acidic azo dyes NN, EBT and Calcon are utilized to analyse quantitatively chlorpheniramine, tripelenamine and diphenhydramine forming insoluble ion pair in aqueous solution at proper pH values between the acidic azo dyes and the sample molecules, these compexes are extracted by organic polar solvents, and organic layer is determined spectrophotometrically. Generally, the absorption maxima of the complexes are shifted to longer wavelengths compare to the absorption maxima of the dyes themselves. The binding ratio of the ion pair forming complex molecules in chloroform soln, are as follows ; NN-antihistamines (chlorpheniramine, tripelennamine, diphenhydramine) are NN-1 to antihisamine-1, EBT-antihistamines are EBT-2 to antithistamines a and Calcon-antihistamines are Calcon-3 to antithistamines-1. These coomplexes in chloroform soln. are very stable, and show higher absorbance than the other organic polar solvents. The binding state of complexes were presumed intermolecular hydrogen bond by their infrared spectra. In the mixture solution of three samples, the aqueous phase is buffered at pH 1.0, and benzene is used to extract ion pair of diphenhydramine EBT complex selectively. At pH 1.0 of aqueous layer, Calon-diphenhydramine complex is also extracted selectively by benzene. However, in this case very small amount of chlorpheniramine-calcon calcon simultaneously. The binding state of diphenhydramine-EBT and diphenhydramine-calcon in benzene are smae as the complexes in chloroform. But the absorption maxima of the complexes in benzene are shifted to shorter wavelenlgths than the complexes in chloroform.

• Bulletin of the Korean Chemical Society
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• v.14 no.5
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• pp.567-574
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• 1993

Mordant Red 19(MR19) is reduced at mercury electrode at -0.67 V vs. Ag/AgCl with two electrons per molecule in pH 9.2 buffer by differential pulse polarography and linear sweep voltammetry. The peak potential is dependent on the pH of solution. The exhaustive electrolysis, however, gives 4 electrons per molecule because of the disproportionation of the unstable hydrazo intermediate. The electrochemical reduction of lanthanide-MR19 complexes is observed at more cathodic potential than that of free ligand. The difference in peak potentials between complex and free ligand varies from 75 mV for $La^{3+}$ to 165 mV for $Tb^{3+}$ and increases with increasing the atomic number of lanthanide. The electrochemical reduction of lanthanide complexes with MR19 is due to the reduction of ligand itself, and it can be potentially useful as an indirect method for the determination of lanthanides. The shape of i-E curves and the scan rate dependence indicates the presence of adsorption and the adsorption was confirmed by potential double-step chronocoulometry and the effect of standing time. Also the surface excess of the adsorbed species and diffusion coefficients are determined. The composition of the complex is determined to be 1 : 2 by spectrophotometric and electrochemical methods.

• YAKHAK HOEJI
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• v.50 no.4
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• pp.215-219
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• 2006

This study was carried out to obtain the basic information for non-saponin contents that can be used to index fresh ginseng roots (Panax ginseng C. A. Meyer) cultivated in the Republic of Korea and China. Non-saponin components in fresh gingeng roots which were cultivated in various areas and ages in Korea were determined. Acidic polysaccharide, total polysaccharide, crude polyacetylene were quantitatively analyzed by using the method of spectrophotometric determination, while the total protein was analyzed by using Lowry method. The results show that there were no statistically significant differences for the average contents of four non-saponins among 4-years-old, 5-years-old, and 6-years-old fresh ginseng roots. Additionally, this study assessed the average contents of non-saponin components in 4-years-old fresh ginseng roots (Panax ginseng C. A. Meyer) which were cultivated in Korea and China. The result showed that the average contents of crude polyacetylene and acidic polysaccharide were statistically significant. Four-years-old fresh ginseng roots cultivated in Korea had the higher average contents of crude polyacetylene and acidic polysaccharide than those cultivated in China. However the average contents of total polysaccharide and total protein had no statistically significant difference.

• Analytical Science and Technology
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• v.35 no.4
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• pp.153-160
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• 2022

A green spectrophotometric method for the determination of cyanide has been proposed using, a green reagent, aqueous extract of blue butterfly pea. The test tube was filled with anthocyanin rich extract (pH 6) and cyanide solution. The reaction was kept constant for 10 minutes at room temperature. The reaction mixture changed color from blue to green as the amount of CN-ions increased. The 620 nm peak intensity increased with CN concentration. Therefore, this wavelength was used for all cyanide analyses. The cyanide calibration curve had a linear range of 0.25-1.00, 1.00-4.00, and 4.00-10.00 mg/L, with a satisfactory correlation coefficient of 0.99 and a LOD of 0.57 mg/L. The recovery ranged from 8.33 to 76.94 percent, indicating that this method is inaccurate at low cyanide concentrations. The intra-day and intermediate precision relative deviations were 0.391-0.871 % and 1.112-1.583 %. An H-bond forms between the C-4 group of the B-carbonyl ring and the HCN molecule according to the B3LYP/TZVP calculation. The method is convenient for cyanide concentrations above the LOQ of 1.09 mg/L, cost-effective, and capable of reducing toxic solvents with acceptable precision. The method could also be used to detect total cyanide in biological, environmental, and industrial waste samples.

• Proceedings of the Korean Society of Crop Science Conference
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• 2021.04a
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• pp.137-137
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• 2021

The study of total phenol (TP) content from 700 rice varieties was evaluated using the UV-Vis spectrophotometric method. The calibration curve of serial diluted gallic acid as a standard of this study showed the acceptable performances (R² = 0.999, mean accuracy 90%) and the mean of % relative standard deviation (%RSD: 0.07%) within the range of 7.8 to 1000 ppm concentrations. The mean value of total phenol content from 700 rice varieties was 2723.15 ㎍/g ranged from 55.48 ㎍/g to 9922.23 ㎍/g and the mean %RSD was 2.5%. Furthermore, this study aim was to analyze and profile individual phenolic compounds in the rice genetic resources to construct an integrative database for development of new rice variety with high functionality for health and understanding of phenolics characteristics in the rice grain. Herein, we analyzed selected 100 rice varieties based on high TP content and identified total 15 phenolic compounds by LC-ESI-MS/MS. Among selected 100 rice genetic resources, the phenolic metabolites consisted of higher amount of flavonoid (catechin) and phenolic acid mainly protocatechuic acid. Further research of more selected rice genetic resources would be continued to provide for an integrative phenolics profile of different rice genetic resources.

• Journal of the Korean Chemical Society
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• v.40 no.2
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• pp.109-116
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• 1996

A matrix modification was studied for the determination of trace germanium in mineral waters by electrothermal atomic absorption spectrophotometry (ET-AAS). For this, the type and quantity of modifier as well as the use of auxiliary modifier were investigated to realize the efficient modification. Germanium suffers from low sensitivity and poor reproducibility in ET-AAS determination because of the premature loss of germanium via volatile germanium monoxide formation when heated in the presence of carbon. Therefore, the addition of a matrix modifier is necessary to stablize the germanium, thermally and chemically. By the addition of palladium (10 ${\mu}g/mL)$ as a single modifier to the sample containing 500 ng/mL germanium, the charring temperature could be raised from 800 to $1000^{\circ}C$, and its absorbance was also increased, but the atomization temperature was not raised. In this case, the absorbance of germanium was not changed in the range of 10∼70 ${\mu}g/mL$ of palladium added. On the other hand, it was considered that the use of a mixed modifier could modifiy the matrix more effectively than with a single modifier. The best results were obtained by using 1% ammonium hydroxide as an auxiliary modifier together with 10 ${\mu}g/mL$ palladium. The charring temperature could be raised from 800 to $1100^{\circ}C$, without any change of the atomization temperature. With above optimum conditions, the trace amount of germanium in several mineral waters were determined by a calibration curve method, and good recoveries of more than 95% were also obtained in the samples in which a given amount of germanium was spiked. The detection limit of this method was about 6.9 ng/mL.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.34 no.1
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• pp.57-62
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• 2008

No matter how small amount of heavy metals it may be cause skin allergies through percutaneous adsorption when existing in cosmetic products as impurities. In order to develop a highly sensitive method for simultaneous determination of $Pb^{2+},\;Fe^{2+},\;Cu^{2+},\;Ni^{2+},\;Zn^{2+},\;Co^{2+},\;Cd^{2+},\;and\;Mn^{2+}$ in coloring agents and cosmetic products with rapidity and accuracy, we carried out the determination on ion chromatography. All of these metals are well separated through a bifunctional ion-exchange column(IonPac CS5A) and detected by post-column reaction and spectrophotometric detection. The calibration graphs are linear($r^2>0.999$) in the range $0.1{\sim}1000{\mu}g/mL$. Detection limits for 200 ${\mu}L$ of sample solution are at the level of ${\mu}g/L$, which is sufficient for judging whether the product is safe or not. The relative standard deviations(RSDs) of the retention time and the peak area are less than 0.21 and 1.24%, respectively. The recovery rates are $97{\sim}104%$. The new method was applied to analyze the amount of heavy metals which were contained in 22 cosmetic products and 11 coloring agents.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.5
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• pp.443-454
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• 2008

Statement of problem: A clinically successful color match is one of the important factor to get an esthetic dental restoration. Dental shade guides are commonly used to evaluate tooth color in restorative procedure. But numerous reports have indicated that common shade guides do not provide sufficient spectral coverage of the natural tooth colors. To address issues associated with the shade guide, distinct avenues have been pursued objective spectrophotometric / colorimetric assessment. Purpose: This study compared the accuracy of tooth color selection of spectrophotometer with that of human visual determination. Three main factors were investigated, namely, the effect of light, the individual variation and the experience of the observer. Material and methods: At the first experiment, on ten patients, one operator independently selected the best matching shade to the unrestored maxillary central incisor, using a Vita Classical Shade Guide in the morning, at noon and in the afternoon. The same teeth were measured by means of a reflectance spectrophotometer. At the second experiment, on ten patients, ten operators (5 experts, 5 novices) selected and measured by the same method above at noon. At the third experiment, the results of the second experiment were divided into two groups, expert and novice, and analyzed. Results: 1. There was significant difference between visual and spectrophotometric assessment (mean ${\Delta}E$ values) in experiment 1, 2, 3 (P < .05). 2. There was no significant difference between experts and novices group, when comparing with each visual and spectrophotometric assessment (mean ${\Delta}E$ values). Conclusion: Spectrophotometer could be used to analyze the shade of natural tooth objectively. Thereby, this method offers the potential tominimize considerably the need for corrections or even remakesafter intraoral try-in of restoration. Furthermore, to achieve its advantage, both the shade-matching environment and communication between dentist and technician should be optimized with use of visual and instrumental shade-matching systems.