• Clean Technology
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• v.27 no.1
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• pp.79-84
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• 2021

In this study, the waste activated carbon used in the painting process was filled into a cylindrical cartridge and the characteristics of desorption by low temperature gas were investigated. Adsorption and desorption experiments of toluene with activated carbon were conducted to determine the flow rate of desorption. In an experiment where desorption was performed while changing conditions at flow rates of 1, 2 and 4 ㎥ min-1, it was determined that 2 ㎥ min-1 was appropriate due to the high THC concentration and desorption time. In the early stage of the desorption of waste activated carbon, 2-butanone and MIBK (methyl isobutyl ketone) with a low boiling point were generated at a high rate in the gas component, and after that, the concentration of THC decreased and the BTX was desorbed at a high rate. The total calorific value of the gas component generated during the desorption of waste activated carbon was 316 kcal kg-1. From repeating the regeneration of waste activated carbon with toluene five times, it was observed that the iodine value and the specific surface area were relatively lower than that of new activated carbon. In the desorption experiment where two cylindrical cartridges were connected in series, the maximum THC concentration was about 470 ppm.

• Analytical Science and Technology
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• v.25 no.6
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• pp.364-369
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• 2012

Isotianil is a novel fungicide which induces systemic acquired resistance in plants. It has excellent preventive effects as low dosages against rice blast which is one of the most serious diseases in rice. The Maximum Residue Limit (MRL) of Isotianil in republic of korea was set to 0.1 mg/kg in rice, so it is necessary to determine levels of Isotianil residues in agricultural commodities for controlling food safety. Therefore, The purpose of this study was to develop analytical method for the determination of isotiical residues in agricultural commodities using GC-NPD/MSD. Isotianil was extracted with acetonitrile from apple, chinese cabbage, hulled rice, mandarin, pepper, and soybean. The extract was diluted with saline water, and then dichloromethane partition was followed to recover this fungcide from the aqueous phase. A solid phase extraction with Florisil cartridge was additionally employed for final clean up. Isotianil was analyzed and quantitated by GC-NPD and confirmed by GC-MSD. Average recovery of Isotianil ranged from 70.0 to 103.9% in six representative agricultural commodities with relative standard deviations less than 10%, and limit of quantification (LOQ) was 0.05 mg/kg.

• Analytical Science and Technology
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• v.22 no.1
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• pp.109-117
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• 2009

The following concentrations of some PAHs were investigated; [benzo(a)anthracene, chrysene, benzo (b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenzo(a,h)anthracene, benzo(g, h, i)perylene, indeno (1,2,3-c,d)pyrene] in fish(n=168) and shellfish(n=40). The methodology involved saponification and extraction with n-hexane, clean-up on Sep-Pak Florisil Cartridges and determination by HPLC/FLD (High Performance Liquid Chromatograph/Fluorescence Detector). Overall method recoveries for 8 PAHs spiked into these products ranged from 88 to 112%. The mean level of benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k) fluoranthene, benzo(a)pyrene, dibenzo(a,h)anthracene, benzo(g,h,i)perylene and indeno(1,2,3-c,d)pyrene in cooked fish was ND, ND, 0.0009, ND, 0.01, ND, ND, ND and in cooked shellfish was 1.84, 3.51, 0.81, 0.38, 0.39, 0.04, 0.20, ND, respectively.

• Korean Journal of Food Science and Technology
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• v.45 no.2
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• pp.148-155
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• 2013

Sulfoxaflor is a new active ingredient within the sulfoximine insecticide class that acts via a unique interaction with the nicotinic receptor. The MRLs (maximun residue limit) of sulfoxaflor in apple and pear are set at 0.4 mg/kg and that in pepper is set at 0.5 mg/kg. The purpose of this study was to develop an analytical method for the determination of sulfoxaflor residues in agricultural commodities using HPLC-UVD and LC-MS. The analysis of sulfoxaflor was performed by reverse phase-HPLC using an UV detector. Acetone and methanol were used for the extraction and aminopropyl ($NH_2$) cartridge was used for the clean-up in the samples. Recovery experiments were conducted on 7 representative agricultural products to validate the analytical method. The recoveries of the proposed method ranged from 82.8% to 108.2% and relative standard deviations were less than 10%. Finally, LC-MS with selected ion monitoring was also applied to confirm the suspected residues of sulfoxaflor in agricultural commodities.

• Analytical Science and Technology
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• v.26 no.2
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• pp.142-153
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• 2013

A new, rapid, and simple analytical method was developed and validated using high performance liquid chromatograph-photodiode array detector (HPLC-PAD) for the determination of lepimectin residues in agricultural commodities. The lepimectin residues in samples were extracted with methanol, partitioned with dichloromethane, and then purified with glass column filled with subsequently to aminopropyl ($NH_2$) solid phase extraction (SPE) cartridge. The purified samples were detected using HPLC-PAD. Correlation coefficient ($R^2$) of both lepimectin $A_3$ and $A_4$ solutions were 0.9999. The method was validated using cucumber spiked with lepimectin at 0.02 and 0.2 mg/kg and pepper, mandarin, hulled rice, potato, soybean at 0.02 and 0.5 mg/kg. Average recoveries were 76.0~114.8% with relative standard deviation less than 10%, and limit of detection (LOD) and limit of quantification (LOQ) were 0.005 and 0.01 mg/kg, respectively. The result of recoveries and overall coefficient of variation of a laboratory results in Gwangju regional KFDA and Daejeon regional KFDA was followed with Codex guideline (CAC/GL 40). Therefore, developed method in this study is accurate, rapid, and appropriate for lepimectin determination and will be used to keep safety of lepimectin residues in agricultural products.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.3
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• pp.276-282
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• 2005

Inferior alveolar nerve block using lidocaine is the most frequent local anesthetic method in the dental treatment, but clinically it is not always successful. The 2% lidocaine cartridge has been used commonly in dental anesthesia. It contains vasoconstrictor and antioxidant, which presents low pH which provides chemical stability and longer shelf life. But alkalinized local anesthetics has less tissue trauma, easier dissociation of the non-ionized base which penetrates nerve sheath, rapid onset and more intensity. In this study, in inferior alveolar nerve block, alkalinized lidocaine using sodium bicarbonate (experimental group) is compared with plain lidocaine (control group) about injection pain, anesthetic onset, duration and postinjection discomfort. In inferior alveolar nerve block, alkalinized lidocaine using sodium bicarbonate showed lower injection pain. There was significant difference statistically from plain lidocaine(p=0.019). Comparing with plain lidocaine, alkalinized lidocaine produced more rapid onset (lip & pulp anesthetic onset), there was no significant difference(p>0.05). but there was boundary significance (0.050.05). These results suggest that addition of sodium bicarbonate to 2% lidocaine(1:100,000 epinephrine) for inferior alveolar nerve block is more effective for reduction of injection pain and onset time.

• Membrane and Water Treatment
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• v.9 no.1
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• pp.17-21
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• 2018

A series of laboratory scale experiments were performed to investigate the feasibility of membrane separation technology for natural rubber (NR) wastewater treatment and reuse. Three types of spiral wound membranes were employed in the cross-flow experiments. The NR wastewater pretreated by sand filtration and cartridge filtration was forced to pass through the ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) membranes successively. The UF retentate, which containing abundant proteins, can be used to produce fertilizer, while the NF retentate is rich in quebrachitol and can be used to extract quebrachitol. The permeate produced by the RO module was reused in the NR processing. Furthermore, about 0.1wt% quebrachitol was extracted from the NR wastewater. Besides, the effluent quality treated by the membrane processes was much better than that of the biological treatment. Especially for total dissolved solids (TDS) and total phosphorus (T-P), the removal efficiency improved 53.11% and 49.83% respectively. In addition, the removal efficiencies of biological oxygen demand (BOD) and chemical oxygen demand (COD) exceeded 99%. The total nitrogen (T-N) and ammonia nitrogen (NH4-N) had approximately similar removal efficiency (93%). It was also found that there was a significant decrease in the T-P concentration in the effluent, the T-P was reduced from 200 mg/L to 0.34 mg/L. Generally, it was considered to be a challenging problem to solve for the biological processes. In brief, highly resource utilization and zero discharge was obtained by membrane separation system in the NR wastewater treatment.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.4
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• pp.300-308
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• 2009

In a pursuit of the development of alternative mobile power sources with a high energy density, a planar and air-breathing PEMFCs with a new type of hydrogen cartridge which uses onsite $H_2$ generated from sodium borohydride ($NaBH_4$) hydrolysis have been investigated for use in advanced power systems. Two types of $H_2$ generation through $NaBH_4$ hydrolysis are available: (1) using organic acids such as sulphuric acid, malic acid, and sodium hydrogen carbonate in aqueous solution with solid $NaBH_4$ and (2) using solid selected catalysts such as Pt, Ru, CoB into the stabilized alkaline $NaBH_4$ solution. It might therefore be relevant at this stage to evaluate the relative competitiveness of the two methods mentioned above. The effects of flow rate of stabilized $NaBH_4$ solution, MEA (Membrane Electrode Assembly) improvement, and type and flow control of the catalytic acidic solution have been studied and the cell performances of the planar, air-breathing PEMFCs using $NaBH_4$ has been measured from aspects of power density, fuel efficiency, energy density, and fast response of cell. In our experiments, planar, air-breathing PEMFCs using $NaBH_4$ achieved to maximum power density of 128mW/$cm^2$ at 0.7V and energy efficiency of 46% and has many advantages such as low operating temperature, sustained operation at a high power density, compactness, the potential for low cost and volume, long stack life, fast star-up and suitability for discontinuous operation.

• Korean Journal of Veterinary Service
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• v.30 no.1
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• pp.13-21
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• 2007

An atmospheric pressure chemical ionization (APcI) LC/MS/MS method was developed for the simultaneous analysis of fluoroquinolones (norfloxacin, ciprofloxacin, enrofloxacin, danofloxacin) residues in eggs. The spiked and blank samples were extracted from whole eggs using 50mM phosphate buffer (pH 7.4). The extract was cleaned up by passage though $Oasis^{(R)}$ MAX extraction cartridge for solid-phase extraction followed by elution with 4% formic acid in methanol. The extract of sample was separated on a Waters $Atlantis^{TM}$ $dC_{18}$ reversed-phase column ($4.6{\times}150mm,\;5{\mu}m$) and analyzed by APcI positive mode mass spectrometry. The mobile phase consists of aqueous 0.2% nonafluoropentanoic acid (NFPA) and methanol. Multiple reaction monitoring (MRM) using the precursor to product ion combinations of m/z $320\;{\dashrightarrow}\;302,\;332\;{\dashrightarrow}\;314,\;360\;{\dashrightarrow}\;342$ and m/z $358\;{\dashrightarrow}\;340$ were used to quantify norfloxacin (NOR), ciprofloxacin (CIP), enrofloxacin (ENR) and danofloxacin (DAN), respectively. The limits of quantification (LOQ) were 7.8ppb for NOR, 8.5ppb for CIP, 8.9ppb for ENR, and 4.8ppb for DAN. Average recoveries of fortified sample at levels of 0.025 to 0.1 ppm were estimated 71.29% for NOR, 75.27% for CIP, 85.51% for ENR and 81.22% for DAN. These results could be applied for the confirmation and quantification in eggs.

• Analytical Science and Technology
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• v.23 no.6
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• pp.572-578
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• 2010

The extraction/clean-up and concentrating of pharmaceuticals from surface water were performed by HLB (Hydrophilic-Lipophilic Balanced) cartridge. The method allows for the simultaneous determination of six pharmaceuticals by HPLC/ESI(+)-MS/MS. Recoveries of the pharmaceutical were between 71.1 to 92.6% (except fenbendazole) and the overall variability of the method was below 11.2% (RSD). The calibration curves for the pharmaceuticals from blank surface water showed good linearities (above $r^2$ = 0.99) in the concentration range of 0.007~1.2 ng/mL. The limit of detection (LOD) and the limit of quantification (LOQ) were 7.2~128.7 pg/mL and 23.8~429.1 pg/mL, respectively. The present analytical method can be useful for monitoring residual pharmaceuticals in surface water and other aquatic samples. High concentrations of iopromide and fenbendazole were detected in a few samples of surface water.