• Archives of Pharmacal Research
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• v.27 no.4
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• pp.460-464
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• 2004

The quality of Alismatis Rhizoma was evaluated by reversed-phase high performance liquid chromatographic method. Alisol B 23-acetate was used as a standard marker for evaluation. This component was fully separated from the other components in the plant extracts on a ODS column. Identifcation of alisol B 23-acetate was carried out by comparing the LC/MS spectrum of separated peak from the extract with that of standard. Alisol B 23-acetate contents in Alismatis Rhizoma obtained from several herbal markets were varied from $0. 15\%$ to $0.56\%$.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.203-206
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• 2003

The liquid limit(LL) test is universally used as a standard test for determining one of the index properties of a clay. There are two methods of determining the LL, Casagrande method and cone penetration method that is fall cone test. The interpretation of the Casagrande method of obtaining the LL is not obvious, but it has been suggested that the fall cone test is essentially a strength test and that the LL test simply ascertains the moisture content at which a clay has a certain standard undrained shear strength. This paper presents a determination of the LL by a single-point method. Results obtained from fall cone that is general method and a single-point method are analyzed by comparison.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.798-801
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• 2001

This research is about slurry wear of SM45C and SUS304, which using standard sand and KUM river sand. The results are as follows ; 1. Mass loss rates of both standard sand and KUM river sand were linearly increased as increasement of time and velocity. 2. The average diameter of sand from relatively, less wear rate and portion of larger particles. 3. Wear resistance was linear with time and velocity of liquid jet regardless of type of sand. Also it was able to evaluate with the formula, HV2/E calibrated with n, the velocity index. 4. The wear surface in liquid jet experiment was smooth. The maximum wear depth was observed at the location, 2~4mm apart from the center in the condition of 90$^{\circ}$of collision angle 6mm of nozzle diameter, and 20mm of collision distance. The sectional shape in radial appeared as 'W' shape.

• Food Science and Biotechnology
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• v.18 no.5
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• pp.1199-1203
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• 2009

Melamine is a chemical intermediate to manufacture amino resins and plastics, which cannot be used as food additive since it can cause kidney stones. A qualitative determination method of melamine residue in powdered and liquid milk was developed using Fourier transform infrared (FTIR) spectroscopic technique. The calibration sets consisted of 21 standard melamine solutions, in which 1% trichloroacetic acid aqueous solution and acetonitrile (3:1, v/v) were used as solvent. The model was validated using 10 standard melamine solutions which were unused to build up the calibration set. Infrared (IR) absorbance peaks specific to almost all chemical groups in melamine molecule were shown in the spectral range between 1,100 and 1,800/cm. Combined partial least squares (PLS)-$2^{nd}$ derivative calibration model coupled with mean centering (MC) mathematical enhancement showed the highest correlation coefficients ($R^2$>0.99). In brief, the FTIR technique can be used for quantitative analysis of melamine in milk samples.

• Journal of the Korea Society for Simulation
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• v.6 no.1
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• pp.53-60
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• 1997

Results from a nonequilibrium molecular dynamics (NEMD) simulation are presented for an argon liquid subject to a shear flow. The segmented molecular dynamics method and the subtraction technique used in NEMD program to reduce the thermal fluctuation noise in data are studied with different shear rates. The standard deviation in the shear stress reduced from 0.030 to 0.004 by the segmented molecular dynamics method for 50 repeated segments. On the other hand, the standard deviation of the data remained the same when the subtraction technique was applied, where as the results of shear stress by constant value in a random way.

• Journal of Pharmaceutical Investigation
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• v.13 no.2
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• pp.59-65
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• 1983

A convenient high performance liquid chromatographic method for the quantitative determination and content uniformity of prednisolone in tablets is described. The prednisolone was chromatographed using a ${\mu}-Bondapak\;C_{18}$ column and the eluent 70% MeOH at a flow rate 1. 0ml/min. Diethylstilbestrol was used as an internal standard. The UV detector response at 254nm was linear over a range of $10{\sim}60{\mu}g/ml$ under conditions of the analysis. Reproducibility studies gave relative standard deviations of $0.3{\sim}0.5%$.

• Bulletin of the Korean Chemical Society
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• v.21 no.5
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• pp.471-476
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• 2000

Liquid chromatography/mass spectrometry with an atmospheric pressure chemical ionization interface (LC/APCI/MS) is evaluated for the simultaneous determination of carbamate pesticides and organophosphorus pesticides in a single chromatographic analysis. APCI mass spectra of those compounds were obtrained to study their ionization characteristics. APCI provided abundant ions such as protonated molecules and characteristic fragment ions for carbamate pesticides and organophosphorus pesticides. To evaluate the feasibility of the LC/APCI/MS for a routine quantitative analysis, the linearity and repeatability of LC/APCI/MS were examined by measuring standard solution mixtures of five carbamate pesticides and four organophosphorus pesticides over the range of 1 to 100 ㎍/mL. Teh peak areas in chromatograms of characteristic ions for those compounds showed less than 3% of variation from run to run. The standard calibration curves for the nine pesticides show good linearity in the concentration range. The detection limits of the LC/APCI/MS system for those compounds range from 0.006 to 0.2 ng.

• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.549-563
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• 2005

The study was carried out to develop and standardize the analytical method of 1,4-dioxane in water. The National Institute of Environmental Research in Korea has monitored for 1,4-dioxane in water since 1998 and it has been detected in environmental water occasionally. But the environmental pollution and analytical method in water is not well known over the world. The trace analytical method at low-${\mu}/L$ level is prerequisite in order to evaluate the residue of 1,4-dioxane in water. Evaluation of the method was demonstrated by comparing and analyzing with liquid-liquid extraction, solid-phase extraction and purge & trap technique. As a result of experiment by standard solutions and raw samples, the precision and accuracy for three methods were obtained within error rate of about 10%. Therefore, three methods were standardized as official monitoring method in Korea. Also, a convenient and simple liquid-liquid extraction method for the analysis of 1,4-dioxane in water was developed by combined with gas chromatography/mass spectrometry and applied to the water samples in Korea

• Asian Journal of Atmospheric Environment
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• v.11 no.1
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• pp.54-60
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• 2017

Quantifying the trace elements in infinitesimal ambient liquid samples (e.g., single raindrop, cloud/fog water, and the soluble fraction extracted from the particles collected for a short time) is an important task for understanding formation processes, heating/cooling rates, and their health hazards. The purpose of this study is to employ an in-air micro PIXE system for quantitative analysis of the trace elements in a thimbleful of reference liquid sample. The bag type liquid sample holder originally designed with $10{\mu}m$ thick $Mylar^{(R)}$ film retained the original shape without any film perforation and apparent peaks of film blank by the end of the analysis. As one of tasks to be solved, the homogeneity of the elemental distribution in liquid reference species was verified by the X-ray line profiles for several references. It was possible to resolve the significant peaks for whole target elements corresponding to the channel number of micro-PIXE spectrum. The calibration curves for the six target elements (Si, S, Cl, Fe, Ni, and Zn) in standard solutions were successfully plotted by concentration (ppm) and ROI of interest net counts/dose (nC).

• Food Science and Biotechnology
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• v.18 no.6
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• pp.1430-1434
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• 2009

The present study used the liquid extraction pretreatment method and developed a liquid chromatographyultraviolet detector (LC-UV) for the simultaneous determination of 14 sulfonamides (SAs) residues in porcine and chicken muscle. Linearity within a range of $50-150\;{\mu}g/kg$ was obtained with the correlation coefficient ($r^2$) of 0.9673-0.9997. The mean recovery of SAs was 55.9-109.7% (relative standard deviations; RSDs 1.7-17.3%) in porcine muscle and 52.8-112.4% (RSDs 2.3-16.9%) in chicken muscle. The limits of detection (LODs) and limits of quantification (LOQs) were 2-32 and $7-96\;{\mu}g/kg$ in porcine muscle, and 4-32 and $13-97\;{\mu}g/kg$ in chicken muscle, respectively. These values were lower than the maximum residue limits (MRLs) established by the European Union. The sum of all SAs residues present should be less than $100\;{\mu}g/kg$.