• Transactions of the Korean hydrogen and new energy society
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• v.17 no.4
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• pp.379-388
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• 2006

Two mesophilic trickling bed bioreactors filled with two different types of media, hydrophilic- and hydrophobic-cubes, were designed and conducted for hydrogen production under the anaerobic fermentation of sucrose. Each bioreactor consisted of the column packed with polymeric cubes and inoculated with heat-treated sludge obtained from anaerobic digestion tank. A defined medium containing sucrose was fed by the different hydraulic retention time(HRT), and recycle rate. Hydrogen concentrations in gas-phase were constant, averaging 40% of biogas throughout the operation. Hydrogen production rate was increased till $10.5\;L{\cdot}h^{-1}{\cdot}L^{-1}$ of bioreactor when influent sucrose concentrations and recycle rates were varied. At the same time, the hydrogen production rate with hydrophobic media application was higher than its hydrophilic media application. No methane was detected when the reactor was under a normal operation. The major fermentation by-products in the liquid effluent of the both trickling biofilters were acetate, butyrate and lactate. In order to run in the long term operation of both reactor filled with hydrophilic and hydrophobic media, biofilm accumulation on hydrophilic media and biogas produced should be controlled through some process such as periodical backwashing or gas-purging. Four sample were collected from each reactor on the opposite hydrogen production rate, and their bacterial communities were compared by terminal restriction fragment length polymorphism (T-RFLP) analysis of PCR products generated using bacterial 16s rRNA gene primers (8f and 926r). It was expressed a marked difference in bacterial communities of both reactors. The trickling bed bioreactor with hydrophobic media demonstrates the feasibility of the process to produce hydrogen gas. A likely application of this reactor technology can be hydrogen gas recovery from pre-treatment of high carbohydrate-containing wastewaters.

• Analytical Science and Technology
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• v.20 no.4
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• pp.308-314
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• 2007

The analytical method of HPLC with the radial-flow electrochemical cell (RFEC) has been developed to determine doxorubicin, epirubicin, nogalamycin, daunorubicin and idarubicin simultaneously by employing a reversed-phase chromatography. Anthracyclines were detected at -0.74 V vs. a Ag/AgCl (0.01 M NaCl) reference electrode, a potential of diffusion current plateau in the mobile phase. At a $V_f$ of 1.0 mL/min doxorubicin, epirubicin, daunorubicin and idarubicin appeared at a retention time ($t_r$) of 6.4 min, 7.4 min, 12.7 min and 18.4 min, respectively, while at a $V_f$ of 0.6 mL/min, doxorubicin, epirubicin, nogalamycin, daunorubicin and idarubicin appeared at a $t_r$ of 9.9 min, 11.5 min, 13.5 min, 19.6 min and 28.7 min, respectively. The linearity between each anthracycline injected ($2.40{\times}10^{-7}M{\sim}1.42{\times}10^{-5}M$) and peak area (charge) was excellent with the square of the correlation coefficient ($R^2$) higher than 0.999. The detection limits were $1.0{\times}10^{-8}M{\sim}1.5{\times}10^{-7}M$ for the five anthracyclines. Within-day precision for the five anthracyclines were in reasonable relative standard deviations less than 3 % ($1.00{\times}10^{-6}M{\sim}1.42{\times}10^{-5}M$) except the lower concentrations less than $0.7{\mu}M$. Solid phase extractions of $1.00{\times}10^{-5}M$ epirubicin, $0.48{\times}10^{-5}M$ nogalamycin and $1.52{\times}10^{-5}M$ daunorubicin from human serum with a $C_{18}$ cartridge resulted in 97 %, 100 % and 90 % of recoveries, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.8
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• pp.1165-1170
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• 2010

A method for the determination of four pesticide compounds, urea (isoproturon), bis-carbamate (phenmedipham), thiocarbamate (pyridate) and vinyllidenediamine (nitenpyram) were examined and analyzed by HPLC with C-18 column ($250\;mm{\times}4.6\;mm$, $5\;{\mu}m$ diameter particle size). Mobile phase consisted of deionized water, acetonitrile and 50 mM $KH_2PO_4$ (pH 2.5). Isoproturon and phenmedipham analytical condition was isocratic elution of the column with 50% solvent A (acetonitrile) and 50% solvent B (deionized water); pyridate was 85% solvent A (acetonitrile) and 15% solvent B (deionized water) at a flow rate of 1 mL/min; and nitenpyram analytical condition was 90% solvent A (50 mM $KH_2PO_4$, pH 2.5) and 10% solvent B (acetonitrile) at a flow rate of 1 mL/min. In results, retention times were 6.12, 8.63, 9.40 and 12.76 min for isoproturon, phenmedipham, pyridate and nitenpyram, respectively. All injection volumes were $10\;{\mu}L$ and the limit of quantitation was 0.05 mg/kg for four pesticide compounds, respectively. Recovery rate test was performed with three farm products, rice, apple and soybean. Four pesticide compounds were spiked at concentrations of 0.05, 0.1 and 0.5 mg/kg. The recovery rates were ranged from 70.18% to 118.08% and the standard deviations of all experiments were within 10%.