• Korean Journal of Clinical Pharmacy
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• v.16 no.1
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• pp.23-27
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• 2006

Doxorubicin (DXR) is a type of anti-cancer drug called an 'anthracycline glycoside', It works by impairing DNA synthesis, a crucial feature of cell division, and thus is able to target rapidly dividing cells. Doxorubicin is a very serious anti-cancer medication with definite potential to do great harm as well as great good. A liquid chromatography-tandem mass spectroscopy (LC-MS/MS) method was developed to identify and quantify DXR in small-volume biological samples. After the addition of internal standard (IS, $5{\mu}L\;of\;1{\mu}M/ml$ daunorubicin methanol solution) into the serum sample, the drug and IS were extracted by methanol. Following vortex for a 1min and centrifugation at 15,000g for 10 min the organic phase was transferred and evaporated under a vacuum. The residue was reconstituted with $350{\mu}L$ of mobile phase and $10{\mu}L$ was injected into C18 column with mobile phase composed of 0.05M ammonium acetate (0.1 M acetic acid adjusted to pH 3.5) and acetonitrile (40:60, v/v). The flow rate was kept constant at $350{\mu}L/min$. The ions were quantified in the multiple reaction mode (MRM), using positive ions, on a triple quadrupole mass spectrometer. The lower limits of quantification for Doxorubicin in plasma and small tissues were approximately 0.5 ng/mL and 0.5 ng/mL respectively. Intra- and inter-assay accuracy (% of nominal concentration) and precision (% CV) for all analytes were within 15%, respectively.

• Journal of Pharmaceutical Investigation
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• v.36 no.1
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• pp.45-51
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• 2006

A rapid, selective and sensitive reversed-phase HPLC method for the determination of dipyridamole in human serum was developed, validated, and applied to the pharmacokinetic study of dipyridamole. Dipyridamole and internal standard, loxapine, were extracted from human serum by liquid-liquid extraction with diethyl ether and analyzed on a Nova Pak $C_{I8}$ column with the mobile phase of 40 mM ammonium acetate:methanol:acetonitrile (35:35:30)(v/v/v, pH 7.8). Detection wavelength of 280 nm and flow rate of 1.0 mL/min were fixed for the study. The assay robustness for the changes of mobile phase pH, organic solvent content, and flow rate was confirmed by $3^3$ factorial design using a fixed dipyridamole concentration (50 ng/mL) with respect to its peak area and retention time. And also, the ruggedness of this method was investigated at three different laboratories using same quality control (QC) samples. This method showed linear response over the concentration range of 2-2000 ng/mL with correlation coefficients greater than 0.999. The lower limit of quantification using 0.5 mL of serum was 2 ng/mL, which was sensitive enough for pharmacokinetic studies of dipyridamole. The overall accuracy of the quality control samples ranged from 103.94 to 105.86% for dipyridamole with overall precision (% C.V.) being 4.60-11.49%. The relative mean recovery of dipyridamole for human serum was 97.64%. Stability studies showed that dipyridamole was stable during storage, or during the assay procedure in human serum. The peak area and retention time of dipyridamole were not significantly affected by the changes of mobile phase pH, organic solvent content, and flow rate under the conditions studied. This method showed good ruggedness (within 15% C.V.) and was successfully used for the analysis of dipyridamole in human serum samples for the pharmacokinetic studies of orally administered Dimor tablet (75 mg as dipyridamole) at three different laboratories, demonstrating the suitability of the method.

• Analytical Science and Technology
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• v.25 no.1
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• pp.25-32
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• 2012

Isotope dilution mass spectrometry (ID-MS) based on liquid chromatography tandem mass spectrometry (LC/MS/MS) was developed for the accurate determination of sorbic acid in tea-drink. An isotope analogue of sorbic acid, $^{13}C_2$-sorbic acid, was obtained by custom synthesis. MS was operated in the negative mode with selected reaction monitoring (SRM) mode of $[M-H]^-$ ${\rightarrow}$ $[M-CO_2H]^-$ channel at m/z 111 ${\rightarrow}$ 67 for sorbic acid and at m/z 113 ${\rightarrow}$ 68 for its isotope analogue. Chromatographic separation was accomplished with a C18 column and an isocratic mobile phase of 55% of 50 mM ammonium acetate (pH 4.5) and 45% of methanol. Homogeneous reference materials were prepared for validation of this method, including repeatability and reproducibility tests, by fortifying tea-drink with sorbic acid in our laboratory. Repeatability and reproducibility studies showed that the ID-LC/MS method is a reliable and reproducible method which provides less than 3.8% of relative standard deviation (RSD) for the analysis of sorbic acid.

• Journal of Oral Medicine and Pain
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• v.34 no.1
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• pp.39-48
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• 2009

Recently there is much interest in the antibacterial activity of nano-sized silver particle (nanosilver) since silver is known to be safe and effective as disinfectant for a long time. Oral malodor is considered to originate in the oral cavity primarily as a result of production of malodorous compounds by oral bacteria. Major compounds responsible for oral malodor are volatile sulfur compounds, which is thought to be generated by the G(-) anaerobic bacteria found normally in the oral cavity, especially on the dorsum of the tongue. The purposes of this study were to investigate the effect of nanosilver on growth of oral malodor generating microorganisms, including Fusobacterium nucleatum, Prevotella melaninogenica, Klebsiella pneumonia, and to determine the optimal culture condition of them. The results were as follows: 1. The optimal culture condition for P. melaninogenica was vacuum culture using desiccator after evacuation of air by vacuum pump in chopped beef meat media. 2. The growth of K. pneumonia was temporarily inhibited by nanosilver (5 ppm and 10 ppm). 3. The morphological alteration and cell damage caused by nanosilver were observed in K. pneumonia.

• Journal of the Korean Chemical Society
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• v.33 no.5
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• pp.484-495
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• 1989

Reactions of $(Et_4N)_2[MoOCl_5]$ with multidentate ligands containing nitrogen or/and oxygen donor atom (EDTA, DTPA, IDA, CyDTA, OX) produce a series of binuclear molybdate (V) complexes. The prepared Mo (V) complexes has been identified by Elemental Analysis, Infrared Spectra, Proton Magnetic Resonance Spectra, and Electronic Spectra. The electrochemical reduction mechanism has been studied by Cyclic voltammetry, Controlled Potential Coulometry, and Spectrophotometry in pH 3.571-10.375 acetate, borate, phosphate/sodium hydroxide, phosphate, ammonium/ammonia buffers. The cyclic voltammogram of the Mo-EDTA, DTPA, IDA, CyDTA complexes at pH < ca. 6.00 have shown two reduction waves. The first reduction wave shows two electron process and the second reduction wave shows two electron process. The cyclic voltammogram of the Mo-EDTA, DTPA, IDA, CyDTA complexes at pH < ca. 8.00 has shown one reduction wave. This reduction wave show four electron process. The cyclic voltammogram of the Mo-OX complex at pH < ca. 7.2 has shown one reduction wave. This reduction wave show four electron process.

• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.30-35
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• 1999

A simple, rapid, efficient method is for extraction of 13 synthetic water-soluble food colours (Tartrazine, Amarnth, Indigo carmine, New coccine, Sunset yellow FCF, Allura red AC, Eosine, Fast Green FCF, Brilliant Blue FCF, Erythrosine, Acid red, phloxine, Rose Bengal) by polyamide resin and for their quantitative by high performance liquid chromatography (HPLC). Colours (coal-tar dyes) were extracted with polyamide resin and then determinated by HPLC. The HPLC conditions using a reverse phase partition type column $(Nova-pak\;C_{18})$, photodiode array (PDA) detector and 1% Ammonium acetate / 60% acetonitrile in water as eluent, were acceptable for various kinds of colorants. By the use of the proposed method, a survey of coal-tar dyes was carried out on 20 samples and that were detected $4.76{\sim}133.47\;ppm$.

• Korean Journal of Environmental Agriculture
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• v.6 no.2
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• pp.31-38
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• 1987

The present study was carried out to determine the effect of the physical, chemical and mineralogical properties of paddy soil on the adsorption and desorption of $Sr^{90}$ from absorbed soils. The results obtained were as follows: 1. Most of the adsorbed $Sr^{90}$ was exchangeable and water soluble. $Sr^{90}$ extracted by ammonium acetate was very high compared to the water soluble fractions, and the ammount decreased with the increase of calcium application, but increased proportionally with the increase of $Sr^{90}$ treatment. 2. The distribution of $Sr^{90}$ in paddy soil depend on the soil type. Average-distribution rates of water soluble, exchangeable and non-exchangeable fractions of $Sr^{90}$ in the soils were 28.6%, 59.3% and 12.1% respectively. 3. The non-exchangeable from of $Sr^{90}$ was high in the soils of high illite and low vermiculite content. 4. The desorption of $Sr^{90}$ from adsorbed soils decreased with the increase of pH and ex-cations of the soils, but increased with the amount of organic matter and clay content in the soil.

• Asian Journal of Turfgrass Science
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• v.20 no.2
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• pp.223-235
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• 2006

Soil testing laboratories unfamiliar with turfgrasses will often overestimate the plant's need for phosphorus and underestimate the need for potassium. This is partly due to differences in rooting between grasses and many garden plants and crops. The grasses are generally more efficient in extracting phosphorus from the soil, reducing their need for phosphorus fertilizer. The fact that crop yield is often the primary objective in field crop production, and is usually of little interest in turfgrass management, may affect soil test interpretation for potassium. Potassium levels above those required for maximum tissue yield of grasses may improve stress tolerance and turfgrasses will usually benefit from higher applications of this element. There are also diffrrences in soil testing philosophies. Some laboratories use the sufficiency level of available nutrients(SLAN) approach, whereas others prefer the basic cation saturation ratio(BCSR) approach. Some will use a combination of the two methods. The use of the BCSR theory easily lends itself to abuse and questionable fertilizer applications and products are sometimes recommended citing imbalances in cation ratios. The usefulness of the BCSR ratio theory of soil testing varies with soil texture and interpretations on tests performed on sand-based media are particularly a problem. Other soil testing problems occur when sand-based media used on sports fields and golf greens contain free calcium carbonate. The ammonium acetate extractant at pH 7.0 dissolves excessive amounts of calcium that can bias cation exchange capacity measurements and measurements of cation ratios. Adjusting the pH of the extractant to 8.1 can improve the accuracy of the testing procedure for calcareous media.

• Analytical Science and Technology
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• v.19 no.3
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• pp.239-243
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• 2006

This method is used for the determination of itraconazole in human plasma by liquid-liquid extraction and high performance liquid chromatography. Felodipine was used as an internal standard. After extraction of the plasma with diethyl ether, the centrifuged upper layer was then transferred. The supernantant was evaporated and then reconsituted with mobile phase. The mobile phase was composed of 10 mM ammonium acetate adjusted to pH 7 by phosphoric acid with a flow rate of 0.2 mL/min. A C18 reversed-phase column with a pre-column was used as the analytial column. Linear detection responses were obtained for itraconzole concentration range for 2~1,000 ng/mL. The correlation coefficient of linear regression($R^2$) was 0.9991, limit of quantification (LOQ) was 2 ng/mL, reproducibility was less than 10.8 %, and accuracy was 97.2~108.2%. This method has been successfully applied to the pharmacokinetic study of itraconazole in human plasma.

• Journal of the Mineralogical Society of Korea
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• v.16 no.2
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• pp.135-149
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• 2003

Domestic zeolite ores are mostly composed of Ca-type clinoptilolite, accompanying a little amounts of mordenite. However, other types of zeolite ores rich in ferrierite, heulandite, or mordenite are less commonly found. Based on the quantitative XRD analysis, zeolite contents are determined to be nearly 50∼90 wt%. Impurities (mostly ＞ 10 wt%) in the zeolite ores chiefly consist of quartz, feldspar, smectite, and opal-CT. The determined CEC values ($CEC_{AA}$ ) of powdery samples (grain size: < 125 $\mu\textrm{m}$) of zeolite ores by the Ammonium Acetate method are mostly higher than 100 meq/100 g. Some zeolites from the Guryongpo area, corresponding to the clinoptilolite ore, are measured to be dominantly high in CEC values ranging 170∼190 meq/100 g. Cation exchange property of the zeolite ores varies greatly depending on the types or zeolite species present in the ores. Despite of the lower grade in zeolite content, the $CEC_{AA}$ of ferrierite ore is comparatively high. Compared to this, the $CEC_{AA }$ of heulandite ore is very low, though the zeolite ore exhibits the highest grade ranging up to about 90 wt%. In addition, the CEC values calculated theoretically from the framework composition of clinoptilolite-heulandite series are not consistent with those determined by the cation exchage experiment. The measured $CEC_{AA}$ of clinoptilolite ores are generally higher than those of heulandite ores. This may be due to the higher Ca abundance in exchangeable cation composition and the presence of probable stacking faults in heulandite. The variation of $CEC_{CEC}$ is roughly proportional, though not strictly compatible, to the zeolite contents in clinoptilolite ores. It seems to be caused by the fact that the $CEC_{AA}$ of clinoptilolite locally varies depending on crystal-chemical diversity, i. e., the variation in framework composition (Si/Al) and exchangeable cation composition (especially, the contents of Ca and K). In addition, the determined CEC values ($CEC_{MB}$ ) of zeolite ores by the Methylene Blue method are much higher than those calculated from smectite contents. It suggests a probable reaction of Methylene Blue ion ($C_{16}$ $H_{18}$ $N_3$S+) with larger-pore zeolites than clinoptlolite-heulandite series, i.e., ferrierite and mordenite as well as with smectite. This can be supported by the fact that the ferrierite ore accompanying little amount of smectite has the highest value in CE $C_{MB}$ .