• Journal of Environmental Health Sciences
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• v.12 no.2
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• pp.11-15
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• 1986

Hydroxlamine effect on the determination of dissolved oxygen by the azide-modified Winkder method and polarography has been studied. It was found that hydroxylamine interference on the dissolved oxygen by the azide-modified Winklet method can be eliminated completely by using permanganate. An inexpensive and convenient polarograph device was constructed. Dissolved oxygen in an air-saturated 0.1 F KCl solution undergoes, independent of hydroxylamine concentrations a two-step irreversible reduction at the dropping electrode the $H_2O_2$ produced in the first step is reduced to $H_2$O in the second. Two waves of equal size result, the first with a half-wave potential (E1/2) at about -0.13 V and the second at about -0.91 V (vs. SCE).

• Journal of the Korean Chemical Society
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• v.7 no.2
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• pp.165-169
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• 1963

12 samples from an assay process chain were submitted to qualitative and quantitative neutron activation analysis for the determination of gold. Gold was detected and quantitatively determined in three samples after a chemical separation consisting of solvent extraction and precipitation steps. Recoveries ranged between 81.0 and 93.6% and results of duplicated determinations were reproducible. Quantitative data were obtained from gamma-spectrometric photopeak-area counting. Interference from fast neutron reactions was negligible.

• Journal of the Korean Chemical Society
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• v.47 no.2
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• pp.89-95
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• 2003

We present improved correlations between theoretical and experimental determination of heat of formation of some aliphatic nitro compounds. The method is based on a previously given theoretical procedure, which is ameliorate through the introduction of suitable bond parameters. The comparison with available experimental data and previous theoretical estimation show a quite satisfactory improvement. Some possible further extensions are pointed out.

• 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.

• Journal of the Korean Chemical Society
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• v.14 no.4
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• pp.281-286
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• 1970

A experiment was performed to investigate the stigmasterol and campesterol in the Panax ginseng. Crude sterol fraction obtained from the ginseng was analysed by TLC and quantitative determination of ${\beta}$-sitosterol was performed with colorimetric method. The results were summarized as follwer, 1. It was observed with ethyl ether-petroleum ether extract of the ginseng that there was no evidence of showing the presence of both free capesterol and stigmasterol but that only ${\beta}$-sitosterol was presence in an significant amount. 2. Average amount of the ${\beta}$-sitosterol was 0.20-0.35mg per gram of the sample.

• Archives of Pharmacal Research
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• v.19 no.6
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• pp.566-569
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• 1996

A sensitivity method has been developed for the detection and determination of niflmic acid(NA) in human urine. Samples were extracted with diethylether. Flunixin (FN) was added to the sample prior to extraction as an internal standard. Niflumic acid was converted to its methyl derivative and analyzed by capillary gas chromatography/negative chemical isonization mass spectrometry. Using selected ion monitoring (SIM), the levels of NA down to 5 pg/ml could be detected in 5 ml spiked urine sample. Calibration curve was linear over the range of 0.5 ppm-50 ppm. The recovery of niflumic acid from urine at 40 pg/ml was to be $91.7{\pm}3.8(n=3)$ and the coefficient of variation was 4.1%.

• Journal of the Korean Chemical Society
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• v.63 no.1
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• pp.45-50
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• 2019

Because arsenic (As) is a chemical substance toxic to humans, there have been extensive investigations on the development of As detection methods. In this study, the electrochemical determination of As on nanoporous gold (NPG) electrodes was investigated using anodic stripping voltammetry. The electrochemical surface area of the NPG electrodes was controlled by changing the reaction times during the anodization of Au for NPG preparation, and its effect on the electrochemical behavior during As detection was examined. The detection efficiency of the NPG electrodes improved as the roughness factor of the NPG electrodes increased up to around 100. A further increase in the surface area of the NPG electrodes resulted in a decrease of the detection efficiency due to high background current levels. The most efficient As detection efficiency was obtained on the NPG electrodes prepared with an anodization time of 50 s. The effects of the detection parameters and of the Cu interference in As detection were investigated and the NPG electrode was compared to flat Au electrodes.

• Journal of the Korean Society of Tobacco Science
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• v.35 no.1
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• pp.1-6
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• 2013

Near InfraRed Spectroscopy(NIRS) is a quick and accurate analytical method to measure multiple components in tobacco manufacturing process. This study was carried out to develop calibration equation of near infrared spectroscopy for the prediction of the amount of chemical components and hot water solubles(HWS) of reconstituted tobacco leaf. Calibration samples of reconstituted tobacco leaf were collected from every lot produced during one year. The calibration equation was formulated as modified partial least square regression method (MPLS) by analyzing laboratory actual values and mathematically pre-treated spectra. The accuracy of the acquired equation was confirmed with the standard error of prediction(SEP) of chemical components in reconstituted tobacco leaf samples, indicated as coefficient of determination($R^2$) and prediction error of sample unacquainted, followed by the verification of model equation of laboratory actual values and these predicted results. As a result of monitoring, the standard error of prediction(SEP) were 0.25 % for total sugar, 0.03 % for nicotine, 0.03 % for chlorine, 0.16 % for nitrate, and 0.38 % for hot water solubles. The coefficient of determination($R^2$) were 0.98 for total sugar, 0.97 for nicotine, 0.96 for chlorine, 0.98 for nitrate and 0.92 for hot water solubles. Therefore, the NIRS calibration equation can be applicable and reliable for determination of chemical components of reconstituted tobacco leaf, and NIRS analytical method could be used as a rapid and accurate quality control method.

• Journal of the Korean Chemical Society
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• v.35 no.6
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• pp.720-724
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• 1991

Simultaneous determination of chloragenic acid (CA), 3,4-o-dicafeoyl quinic acid(3,4-DCQA), 4,5-o-dicaffeoyl quinic acid (4,5-DCQA) and linarin in Chrysanthemum sibiricum Fisher was newly established by a reversed-phase high performance liquid chromatography (HPLC). Sample was extracted with 20 ml methanol for 4 hrs. The extract was cleaned up by using Sep-Pak $C_18$ cartridge and 4 ml methanol-$H_2$O(1 : 1) as eluent. Their determination was performed by means of RP-HPLC with Bondapak $C_18$ column (30 cm ${\times}$ 3.9 mm i.d., 10 ${\mu}m$ and gradient elution mode as methanol-5 mM $H_3PO_4$ solution (30 : 70). The established method was applied to various samples purchased. As a result, their content ranges showed to be 0.35~0.55% for CA, 0.46~0.76% for 3,5-DCQA, 0.077~0.23% for 4,5-DCQA and 0.16~2.72% for linarin, respectively.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.3
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• pp.378-385
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• 2013

The aim of this study was to examine the effect of variety and growing conditions of wheat on broiler performance and nutrient digestibility. One hundred and sixty-four wheat samples, collected from a wide range of different sources, locations, varieties and years, were analyzed for a range of chemical and physical parameters. Chemical and physical parameters measured included specific weight, thousand grain weight (TG), in vitro viscosity, gross energy, N, NDF, starch, total and soluble non-starch polysaccharides (NSP), lysine, threonine, amylose, hardness, rate of starch digestion and protein profiles. Ninety-four of the wheat samples were selected for inclusion in four bird trials. Birds were housed in individual wire metabolizm cages from 7 to 28 d and offered water and feed ad libitum. Dry matter intake (DMI), live weight gain (LWG) and gain:feed were determined weekly. A balance collection was carried out from 14 to 21 d for determination of apparent metabolizable energy (AME), ME:gain, DM retention, oil and NDF digestibility. At 28 d the birds were sacrificed, the contents of the jejunum removed for determination of in vivo viscosity and the contents of the ileum removed for determination of ileal DM, starch and protein digestibility. The wheat samples used in the study had wide-ranging chemical and physical parameters, leading to bird DMI, LWG, gain:feed, ME:GE, AME content and ileal starch and protein digestibility being significantly (p<0.05) affected by wheat sample. A high level of N fertilizer application to the English and NI wheat samples tended to benefit bird performance, with increases of up to 3.4, 7.2 and 3.8% in DMI, LWG and gain:feed, respectively. Fungicide application also appeared to have a positive effect on bird performance, with fungicide treated (+F) wheat increasing bird DMI, LWG and gain:feed by 6.6, 9.3 and 2.7%, over the non-fungicide treated (-F) wheats. An increase (p<0.1) of 9.3% in gain:feed was also observed at the low seed rate of 40 compared to 640 seeds/$m^2$. It was concluded that the type of wheat sample and environmental growing conditions significantly affects bird performance when fed wheat-based diets.