• Journal of the Korean Chemical Society
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• v.36 no.1
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• pp.95-99
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• 1992

A spectrophotometric method for the determination of copper using N,N'-Oxalylbis(salicylaldehyde hydrazone) as a chromogenic reagent has been developed. Determination has been performed by measuring the absorbances of the copper complexes in solutions containing 60% dimethylformamide (pH 2) at 422 nm. The method allows the determination of 0.4${\sim}$1.8 ${\mu}$g/ml of copper and has been applied to its determination in synthetic mixtures and alloy samples.

• Bulletin of the Korean Chemical Society
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• v.25 no.1
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• pp.127-129
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• 2004

• 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 $6.6{\sim}9.4{\times}10^4\;mol^{-1}l\;cm^{-1}$.

• Archives of Pharmacal Research
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• v.27 no.11
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• pp.1114-1119
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• 2004

This paper describes the quantitative determination of flavonoids, tannins and ellagic acid in the leaves from wild and cultivated variations of Rubus L. species (Rosaceae): raspberry (2 wild and 13 cultivars) and blackberry (3 wild and 3 cultivars). The content of flavonoids was analyzed using spectrophotometric (the Christ-M llers method) and HPLC analysis after acid hydrolysis. The content of tannins was determined by the weight method, with hide powder, described by German Pharmacopoeia 10 (DAB 10). Ellagic acid content was examined using the HPLC method after acid hydrolysis. Flavonoid content, determined using the Christ-Muller's method was higher for the blackberry leaves than for the raspberry leaves and varied between 0.46% and 1.05%. Quercetin and kaempferol were predominant in all samples analyzed using the HPLC method. The highest flavonoid content was found in the leaves of R. nessensis (1.06%); with results in all of the examined samples varying between 0.27% and 1.06%. The concentration of ellagic acid in all species was determined after acid hydrolysis and ranged from 2.06% to 6.89%. The leaves of raspberries are characterized by greater amounts of tannins (varying between 2.62% and 6.87%) than the leaves of other species. The results from this study indicate that the analyzed species are a rich source of flavonoids, ellagic acid and tannins, which may be used for the quality assessment of Rubus L. species leaves.

• Journal of the Korean Chemical Society
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• v.12 no.2
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• pp.51-54
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• 1968

Rapid flame spectrophotometric method is developed to determine a small amount of sodium in zircon frit and high purity zirconium compounds. The instrumental characteristics and the optimum conditions are studied and a comparison between calibration curve method and standard addition method is made.

• Journal of the Korean Chemical Society
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• v.68 no.1
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• pp.20-24
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• 2024

This article presents the advantages of utilizing gossypol and its derivatives as reagents for iron (III) (Fe (III)) ions. A novel spectrophotometric method has been developed for the determination of Fe (III) using gossypol derivatives in the presence of a universal buffer solution. Optimal conditions have been identified, and the composition and stability constants of the Fe (III) complex with gossypolacetic acid have been determined.

• Journal of Pharmaceutical Investigation
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• v.2 no.1
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• pp.14-17
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• 1972

Spectrophotometric determination of isonicotinic acid hydrazide sodium methane sulfonate was examined and a new method has been established. Isonicotinic acid hydrazide sodium methane sulfonate reacts with acetylacetone solution (NASH Reagent) to produce a yellow dye, which exhibits absorption maximum at about $412\;m{\mu}$. Limits of masurement of isonicotinic acid hydrazide sodium methane sulfonate was $20-100{\mu}g/ml$. By this method isonicotinic acid hydrazide methane sulfonate can be determined in the presence of isonicotinic acid hydrazide.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.421-425
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• 2001

Among the many parameters describing water quality, total nitrogen content(TN) is regarded as important one in relation to water quality management of the waterbodies for its role in eutrophication process. This study evaluated for accuracy, convenience and promptness of nitrogen analysis methods : (1)UV spectrophotometric method, (2)summation method, (3)cadmium reduction method. And, the detection limit of each method was calculated using EPA method. The UV spectrophotometric method after oxidation appears to be more convenient and accurate in determination of the TN contents than the summation method and cadmium reduction method. The summation method is necessary to separate determinations of the organic nitrogen, ammonia, nitrite, and nitrate. And, because summation method has many other methods for each contents, it can be detected for wide range of concentration.

• Journal of the Korean Chemical Society
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• v.18 no.6
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• pp.415-420
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• 1974

A simple and rapid spectrophotometric method has been found for the determination of nitrate content in natural water according to brucine method by means of neither particular apparatus nor troublesome procedures. Brucine reacted with nitrate in the presence of 30 N sulfuric acid to develop stable color with good reproducibility after 30 minutes reaction at $60^{\circ}C$<\TEX>. An essentially linear relationship to the nitrate concentration was observed in the range of 0.07~0.6 ppm at 410 nm, and it was established that the number of absorbing species in the reaction system was only one between 400 and 490 nm. Among the interferences, nitrite could be removed by the addition of methanol.

• Journal of the Korean Chemical Society
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• v.15 no.1
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• pp.5-9
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• 1971

A separation scheme using cation exchange procedure is designed specifically for the rapid determination of thorium in monazite samples. All the coexisting ions in monazite, including rare earth ions, are eluted with 3N hydrochloric acid. The remaining thorium is eluted from the resin column with 5N sulfuric acid prior to spectrophotometric determination with thorin reagent. The radioactive tracers and spectrophotometric methods were used to confirm the quantitative elution of thorium and also the chemical purity of the eluted thorium from the column.