• Korean Journal of Veterinary Research
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• v.37 no.1
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• pp.195-202
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• 1997

A method for the isolation by matrix solid phase dispersion method and liquid chromatographic determination of enrofloxacin and ciprofloxacin in pork muscle tissue is presented. Blank or enrofloxacin and ciprofloxacin spiked samples(0.5g) containing 0.05g oxalic acid were blended with $C_{18}$(octadecylsilyl derivatized silica) packing material. After homogenization, $C_{18}$/muscle tissue matrix was transferred to glass column made from 10ml glass syringe and filter paper, and compressed to 4~4.5ml volume. A column was washed with 8ml of hexane and dried under vacuum. Interfering materials were removed by ethylacetate 8ml and dried, following which enrofloxacin and ciprofloxacin were eluted with 8ml of methanal under gravity. The eluate containing enrofloxacin and ciprofloxacin wase free from interfering compound when analysed by HPLC with UV detection at 278nm. Enrofloxacin and ciprofloxacin showed linear response with UV detector at the range of $0.05{\sim}1.0{\mu}g/ml$ and eluted within 5ml elution volume of methanol from the matrix. Fortified sample containing 0.05g oxalic acid represented more good recoveries than that of control sample. Average percentages of enrofloxacin and ciprofloxacin were $93.30{\pm}4.56%$ and $91.84{\pm}4.17%$, respectively, for the concentration range(0.05, 0.1, 0.25, 0.5 and $0.75{\mu}g/g$). The interassay variability of enrofloxacin was $6.02{\pm}5.33%$ with an intra-assay variability of 4.89% and $6.75{\pm}2.68%$ with 4.54% for ciprofloxacin. Detection limit of enrofloxacin and ciprofloxacin was $0.030{\mu}g/g$ in the spiked sample.

• Journal of the Korean Ceramic Society
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• v.31 no.4
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• pp.443-447
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• 1994

Compacts of mixed SiO2-Si powder were liquid phase sintered at 145$0^{\circ}C$ for up to 60 min in a hydrogen atmosphere. In contrast to the conventional microstructures of liquid phase sintered materials, the specimens showed that the solid phase of SiO2 formed a matrix while the liquid phase of Si was the dispersed in the solid matrix. The dispersion of liquid Si pockets was attributed to the high wetting angle of liquid Si on solid SiO2. Because of relatively high solubility of SiO2 in liquid Si at 145$0^{\circ}C$, SiO2 particles accommodated their shape via a solution-reprecipitation process. The liquid Si pockets grew by coalescing with their neighbour pockets. In the latter stage of the sintering, plate-shape grains appeared in the liquid Si pockets. The grains were SiO2 phase precipitated from the liquid Si which was oversaturated with oxygen during cooling to room temperature. By the formation and subsequent removal of the gaseous SiO phase due to the reaction between SiO2 and Si, the specimens became porous.

• Journal of the Korean Society of Tobacco Science
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• v.36 no.1
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• pp.12-19
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• 2014

A matrix solid-phase dispersion (MSPD) method was developed for extracting and cleaning-up the selected agrochemicals in tobacco using gas chromatography-mass spectrometry with selected ion monitoring (GC/MS-SIM). Different parameters of the method were investigated and optimized, such as the type of solid-phase (alumina, $C_{18}$ and Florisil) and eluent (acetone, acetonitrile, ethylacetate and n-hexane). The best results were obtained using 0.5 g of tobacco sample, 1.0 g of $C_{18}$ as dispersant sorbent, 1.0 g of Florisil as clean-up sorbent and acetonitile saturated with n-hexane as eluting solvent. The method was validated using tobacco samples fortified with agrochemicals at their different concentration levels. This method gave good linearity for the selected agrochemicals of ranging from $0.01{\mu}g/mL$ to $0.1{\mu}g/mL$. Recoveries of the selected agrochemicals in tobacco were more than 80 % and reproducibilities were found to be better than 10 % RSD. Those results suggested that the analytical procedure including MSPD method in combining with GC/MS could be applicable to the rapid determination often the selected agrochemicals in tobacco.

• Journal of Food Hygiene and Safety
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• v.18 no.2
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• pp.43-50
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• 2003

A liquid chromatographic method, using matrix solid-phase dispersion (MSPD) is developed for the extraction of residual furazolidone in chicken eggs. Blank or fortified egg samples (0.5 g) were blended with Octadecylsilyl (Bulk $C_{18}$, 40${\mu}{\textrm}{m}$, 18%. load, endcapped. 2 g) derivatized silica. After homogenization, $C_{18}$/egg and Na$_2$S $O_4$matrix were transferred to a column made of 10 ml glass syringe and filter paper and compressed 4.0∼4.5 ml volume. The column was washed with 8 ml of hexane and dried under $N_2$ gas. Furazolidone was eluted with acetonitrile (8 ml) under gravity. The eluate containing furazolidone was free from interfering compounds when analyzed by HPLC with UV detection (365 nm, photodiode array). Calibration curves were linear (r = 0.99985) and inter- (1.47%) and intra-assay (5.29%) variabilities for the concentration range examined (7.8∼497 ng/g of eggs, 20 ${mu}ell$ injection volume) were indicative of an acceptable methodology for the analysis of furazolidone. Average recovery of furazolidone added to egg was 96.2%. The limit of detection for the proposed method was 1 ng/g for furazolidone. The method using MSPD is proposed as an alternative assay to the classical method which involves the use of large volumes of a harmful solvent and requires a long tedious separation and clean-up processes prior to its determination.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.3
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• pp.581-593
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• 1990

A semi-solid alloy in which solid and liquid phase are co-existing is obtained by strirring of Al7075 molten metal. A semi-solid alloy is dependent on the corresponding temperature within the solid-liquid range, and the process parameters should be controlled accurately to obtain the homogeneous semi-solid alloy. The possibility o homogeneous fiber-reinforce aluminum alloy by addition of $Al_{2}$O$_{3}$ short fibers with vigorous agitation was investigated. The billet of composite materials was fabricated by squeeze casting, and homogeneous dipersion state of fibers in billet of fabricated metal matrix composites was observed. A slurry of semi-solid short fiber metal matrix composites is used in the direct rolling process, and this process showed the fabrication possibility of metal matrix composite sheets. The fabricated sheet was tested regarding vickers hardness, elongation and micro-structure. It has become clear that mashy state processing and working are very useful to obtain parts of composites material closed to near net shape.

• Korean Journal of Veterinary Service
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• v.22 no.1
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• pp.15-23
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• 1999

A multiresidue, simple and rapid isolation technique known as matrix-solid phase dispersoin (MSPD) for the extraction and quantitative gas chromatographic/electron capture detection (GC/ECD) determination of 14 organochlorinated pesticides($\alpha$-BHC, ($\beta$-BHC, ($\gamma$-BHC, aldrin, dieldrin, endrin, heptachlor, ($\alpha$-endosulfan, ($\beta$-endosulfan, endosulfan sulfate, p,p'-DDE, o,p'-DDD, p,p'-DDD, p,p'-DDT) from meat fats. The 14 pesticide were fortified into meat fat(0.5g) and blend with 2g $C_{18}$, $C_{18}$meat fat matrix blend and 2g activated florisil comprise an extraction column from which the pesticides are eluted by adding 8ml acetonitrile. Then 2${\mu}\ell$ of the eluate is analyzed by GC/ECD. Unfortified blank controls are tested similarly. The eluate contained all the pesticide analytes and was free of interfering coextractants. Recovery rate(31.3-500ng/g) were ranged from 80$\pm$4% to 97$\pm$4%. Any organochlorinated pesticides were not detected in 120 samples of beef and pork collected from slaughter houses in Kyeonggi province.

• Journal of the Korean Society for Heat Treatment
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• v.21 no.5
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• pp.251-258
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• 2008

A transmission electron microscope investigation has been performed on the morphology of dislocations in deformed ${\gamma}^{\prime}-Ni_3(Al,Ti)$ alloys containing fine dispersion of disordered ${\gamma}$ particles. Superlattice dislocations dissociate into fourfold Shockley partial dislocations in a uniform supersaturated solid solution of the ${\gamma}^{\prime}$ phase. Dislocations are attracted into the disordered ${\gamma}$ phase and dissociate further in the particles. At any stage of aging, dislocations cut through the particles and the Orowan bypassing process does not occur even in the over-aged stage of this alloy system. The work necessary to pull the dislocation away from the disordered particles into the ordered matrix should mainly contribute to increase the strength of the ${\gamma}^{\prime}$ phase containing fine dispersion of the disordered ${\gamma}$ phase.

• The Korean Journal of Pesticide Science
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• v.4 no.1
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• pp.26-31
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• 2000

An analytical method was approached to determine the residues of benzimidazole fungicides in soybean sprouts and was compared with traditional solvent-based method of extraction, solid phase extraction(SPE) and matrix solid phase dispersion(MSPD). The recoveries of carbendazim for liquid-liquid extraction (LLE), SPE and MSPD in soybean sprouts were $69.25{\sim}79.16$, $79.99{\sim}90.42$ and $92.40{\sim}98.48%$, respectively. The recoveries of thiabendazole for LLE, SPE and MSPD in soybean sprouts were $64.86{\sim}83.26$, $79.12{\sim}94.04$ and $65.44{\sim}73.92%$, respectively. The residues of carbendazim by elapsed time under our cultivated soybean sprouts program found $0.10{\sim}0.25$ mg/kg after 5 days and trace concentration of carbendazim was detected after 7 days. Of the 448 samples analyzed, less than 1.5% had residues of carbendazim ranged from 0.05 to 0.37 mg/kg.

• Journal of Korea Foundry Society
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• v.13 no.3
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• pp.248-258
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• 1993

A semi-solid alloy in which solid and liquid phase are co-existing is obtained by stirring of A17075 molten metal. A semi-solid alloy is dependent on the corresponding temperature within the solid-liquid range, and the process parameters should be controlled accurately to obtain the homogeneous semisolid alloy. The fabrication possibility of fiber-reinforced aluminum alloy containing $Al_2O_3$ short fibers with vigorous agitation of short fibers were obtained by control of stirring time, solid fraction and impeller speed in extrusion billet fabrication processes. The microstructure to extrusion billet fabricated by low pressure casting was investigated for fiber dispersion state. The relationship between the extrustion force and velocity at hot extrustion, the flow strain and extrusion ratio were theoretically described. The surface defects with lubricants and without lubricant after hot extrusion were investigated. The composites materials after hot extrusion were measured by vickers hardness with extrusion ratio. It has become clear that the secondary working such as hot extrusion was very useful to obtained improved the mechanical properties of metal matrix composites.

• Korean Journal of Veterinary Service
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• v.29 no.3
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• pp.317-330
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• 2006

This study was conducted to develop the analytical method about simultaneous determination for synthetic antimicrobials in muscle by high performance liquid chromatography - mass selective detector (HPLC- MSD). Solid phase extraction (SPE), matrix solid phase dispersion (MSPD) and liquid-liquid extraction (LLE) have been adapted as pretreatment procedures for HPLC- MSD. Among various solvent tested, methanol was chosen for extraction of synthetic antimicrobials in muscles. For the optimized response, the values of various MS parameters including fragment voltage, drying gas flow, nebulizer pressure, drying gas temperature were verified. The average recovery rates using MSPD and SPE for muscles of bovine and pork were 78.9-127.1% and 78.3-121.7%, respectively. This method was verified the satisfactory performance for fourteen synthetic antimicrobials excepting carbadox in muscle of pork as detection limit of $0.05{\mu}g/g$ on API/ES SIM mode.