• Journal of Food Hygiene and Safety
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• v.8 no.1
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• pp.9-15
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• 1993

In an attempt to quantitate and qualitate residual antibiotics and antibacterial agents in meat simultaneously, we studied a gas chromatography-mass spectrometry(GC/M8) analysis. For a simultaneous analysis of penicillin G, chloramphenicol and thiamphenicol in meat, a simple and rapid clean-up procedure including extraction with 0.01 M EDTA-2Na Mcilvaine buffer (pH 4.0), defatting with n-hexane, and elution with 0.01M-methanolic oxalic acid from Bond Elute $C_{18}$ cartridge, and quantitation by selected ion monitoring (SIM) mode after derivatization was performed. The recoveries (%) of penicillin G, chloramphenicol and thiamphenicol (CV, %) at 1 ppm fortification level were 63.5 (7.6), 76.3 (8.1) and 84.7 (2.0), and the detection limits of those were 0.6, 0.085 and $0.084\;\mu\textrm{g}$ beef, respectively. This method using 81M mode allows excellent detection and quantitation of residual antibiotics and antibacterial agents in meat. Moreover, confirmation by a full scan electron impact mass spectrum is possible if residual level in the sample in above 1 ppm.

• Bulletin of the Korean Chemical Society
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• v.27 no.9
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• pp.1439-1444
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• 2006

A $Cu^{2+}$ ion-selective membrane microelectrode has been fabricated from poly vinyl chloride (PVC) matrix membrane containing a new symmetrical hexadentate Schiff,s base 2-{1-(E)-2-((Z)-2-{(E)-2-[(Z)-1-(2-hydroxyphenyl)ethylidene]hydrazono}-1-methylpropylidene)hydrazono]ethyl}phenol (HDNOS) as a neutral carrier, Potassium tetrakis(4-chlorophenyl) borate (KTpClPB) as an anionic excluder and o-nitrophenyloctyl ether (NPOE) as a plasticizing solvent mediator. The microelectrode displays linear potential response in the concentration range of $1.0\;{\times}\;10^{-5}-1.0\;{\times}\;10^{-11}$ M of $Cu^{2+}$. The microelectrode exhibits a nice Nernstian slope of 25.9 ${\pm}$ 0.3 mV $decade^{-1}$ in the pH range of 3.1-8.1. The sensor has a relatively short response time in whole concentration ranges ($\sim$5 s). The detection limit of proposed sensor is $5.0\;{\times}\;10^{-12}$ M (320 pg/L), and it can be used over a period of eight weeks. The practical utility of the sensor has been demonstrated by using it as an indicator electrode in the potentiometric titration of $Cu^{2+}$ with EDTA. The proposed membrane electrode was used for the direct determining of $Cu^{2+}$ content in black and red pepper, and in waste water samples.

• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1581-1586
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• 2006

A La (III) ion-selective membrane sensor has been fabricated from poly vinyl chloride (PVC) matrix membrane, containing 3-hydroxy-N'-(pyridin-2-ylmethylene)-2-naphthohydrazide (HPMN) as a neutral carrier, potassium tetrakis (p-chlorophenyl) borate (KTpClPB) as an anionic excluder and ortho-nitrophenyloctyl ether (NPOE) as a plasticizing solvent mediator. The effects of membrane composition and pH as well as the influence of the anionic additive on the response properties were investigated. The sensor with 30% PVC, 62% solvent mediator, 6% ionophore and 2% anionic additive, shows the best potentiometric response characteristics. It displays a Nernstian behavior (19.2 mV per decade) across the range of $1.0{\times}10^{-2}-1.0{\times}10^{-7}$ M. The detection limit of the electrode is $7.0{\times}10^{-8}$ M ($\sim$10 ng/mL) and the response time is 15 s from $1.0{\times}10^{-2}$ up to $1.0{\times}10^{-4} $M and 30 s in the range of $1.0 {\times}10^{-5}-1.0{\times}10^{-7}$ M. The sensor can be used in the pH values of 3.0-9.0 for about seven weeks. The membrane sensor was used as an indicator electrode in the potentiometric titration of lanthanum ions with EDTA. It was successfully applied to the lanthanum determination in some mouth wash preparations.

• Bulletin of the Korean Chemical Society
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• v.26 no.4
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• pp.579-584
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• 2005

The 3-[(2-furylmethylene)amino]-2-thioxo-1,3-thiazolidin-4-one (FTT) was used as an excellent ionophore in construction of a $Zn^{2+}$ PVC-based membrane sensor. The best performance was obtained with a membrane composition of 30% poly(vinyl chloride), 62% nitrobenzen (NB), 3% FTT and 5% sodium tetraphenyl borate (TBP). This membrane sensor shows very good selectivity and sensitivity towards $Zn^{2+}$ over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The membrane sensor revealed a great enhancement in selectivity coefficients for $Zn^{2+}$ ions, in comparison to the previously reported $Zn^{2+}$ membrane sensors. Theoretical studies also showed the selective interaction of TFF and $Zn^{2+}$ ions. The proposed membrane sensor exhibits a Nernstian behavior (with slope of 29.3 ${\pm}$ 0.3 mV per decade) over a wide concentration range (1.0 ${\times}$ $10^{-6}$-1.0 ${\times}$ $10^{-2}$) with a detection limit of 8.5 ${\times}$ $10^{-7}$ M (52 ng mL$^{-1}$). It shows relatively fast response time, in the whole concentration range ($\lt$ 20 s), and can be used for at least 10 weeks in a pH range of 3.0-7.0. The proposed membrane sensor was successfully used in direct determination of $Zn^{2+}$ ions in wastewater of industrial zinc electroplating companies, and also as an indicator electrode in titration with EDTA.

• Journal of Surface Science and Engineering
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• v.1 no.1
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• pp.5-13
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• 1967

Up to this date, numerous methods of analysis of electropling solutions are published. Some, however, need lots of works before reaching final results, or require high technique and special instruments, and also some are unaccurate due to unclearnes of end point. Like our undevelop countries, technicians of electroplating shops are most high school graduates or under, and have not much knowledge on chemistry. Furthermore, those technicians have to control their plating solutions by themselves without having enough analytical laboratory equipment . Therefore, in this paper the simplest, besides accurate method is investigated after comparing numerous methods published. Among the methods of copper determinations from acid and alkaline copper plating baths, EDTA titration method are chosen, due to these methods are the simpest and fastest for the evaluation of metal content, without requirng any special instrument. For acid copper solutions, chelate titrations were accurate enough. Since the end point of titration of chelate method is variable according to the kind of indicators and other metal's coexisitence as well as solution component, many difficulties were encountered from cyanide copper, on the contrary of acid copper bath. PAN , PV, and MX indicators were tried , but it is found that MX is the best. In chyanide solution ,due to cyanide is the masking reagent , elimination of this component is essential , and finally found that elimination CN-by precipitation with AgNO$_3$ solution was the simplest and the most accurate way among others. This method was very accurate for the new plating solutions even coexistence with organic brightners. However used solutions for long months running have to be predetermined the accurate copper value by thiosulfate method form time to time, before chelate titration by means of AgNO$_3$ precipitation. Always some constant deviations will be seen according to the solutions nature. Therefore those deviation values have to be compensated each time.

• Analytical Science and Technology
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• v.37 no.4
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• pp.211-219
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• 2024

This study presents a sensitive and reliable method for determining tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC) residues in shrimp samples. A two-step process involving liquid-liquid extraction (LLE) followed by solid-phase extraction (SPE) was developed prior to HPLC analysis. The target analytes were effectively extracted using EDTA/McIlvaine buffer (pH 4.0): methanol (80:20, %v/v), with subsequent clean-up using a C18 SPE cartridge. HPLC separation was conducted on a C18 column (250 mm × 4.6 mm i.d., 5 ㎛) at 30 ℃, using 0.01 % trifluoroacetic acid (A) and acetonitrile (B) as the mobile phase. A gradient elution protocol was applied, transitioning from 85(A):15(B) %v/v to 70(A):30(B) %v/v at 7 min, with a 5 min hold, followed by adjustment to 85(A):15(B) %v/v for 13-14 min. The detection was performed using photodiode array (PDA) at 365 nm with a flow rate of 1.0 mL/min. The calibration curves exhibited good linearity within a concentration range of 0.4-6.0 ㎍/mL (R² > 0.995). The limits of detection (LOD) for TC, OTC, and CTC in shrimp were 0.034, 0.029, and 0.021 ㎍/mL, respectively. The limits of quantitation (LOQ) for TC, OTC, and CTC were found to be 0.114, 0.097, and 0.071 ㎍/mL, respectively. Recoveries of TC, OTC, and CTC from spiked shrimp samples ranged from 91.0 % to 95.5 %, 92.4 % to 97.2 %, and 93.3 % to 96.6 %, respectively. This method was successfully applied to the determination of TC, OTC, and CTC residues in shrimp samples sourced from various local markets.

• Journal of agricultural medicine and community health
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• v.22 no.1
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• pp.61-74
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• 1997

In case of tissue invading nematode, proteolytic enzyme was required at their parasitic life. Proteinases obtained from these parasites(Toxocara canis, Ansakis spp. and Trichinella spiralis) were extracted, isolated and further purified. And then the analysis for activity and inhibitory effect of proteinases were performed by appropriate substrate. Determination of protein as a circulating antigen was done in use of infected animal serum with above parasites, respectively. For above experimental objects, following procedures were performed. First, enzymatic activity was measured in use of azocasein and inhibitory effect of porteinase were studied by various inhibitors. Second, partially purified proteins containing enzymatic activity were obtained by ion exchange chromatography, ultrafiltration and electrophoretic elution. Third, role of the partially purified protein as a circulating antigen. The results obtained were as follows : 1. Enzymatic activity of each nematode proteinase was varied according to pH. Optimal pH of Toxocara canis, Ansakis spp. and Trichinella spiralis were pH 6.0, pH 5.5 and pH 6.5, respectively. The optimal molarity of buffer was 0.1M phosphate buffer. Although little difference between these proteinases was observed, temperature stability was at least maintained at $4^{\circ}C$ until 5 days. 2. In case of Ansakis spp. and Toxocara canis, enzymatic activity of these proteinases was considerably inhibited by Leupeptin and EDTA. For maximum enzymatic activity of above proteinases, it was required that cysteine residue of enzyme should be protected. And it was suggested that metallo type was contained in enzyme active site. Proteinase of Trichinella spiralis contained metallo type also. 3. Although partial purification was performed in Ansakis spp. and Toxocara canis, proteins maintaining enzymatic activity were identified as a circulating antigen. From SDS-PAGE and immunoblot, 25 kDa was presented in Ansakis spp.. Specific antigen of Toxocara cains was 110 kDa protein fraction. 55 and 42 kDa proteins were reacted with normal serum. Trichinella spiralis 60 kDa protein fraction was successfully purified from excretory materials in culture. As a result of immune-reaction with Trichinella spiralis infected serum, highly purified 60 kDa protein was maintained antigenicity until final purification step.

• Microbiology and Biotechnology Letters
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• v.37 no.2
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• pp.99-104
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• 2009

The $\beta$-glucosidase gene from Streptomyces coelicolor A3(2) was cloned and expressed in Escherichia coli. The ORF consisted of 1377 nucleotides encoding 51 kDa in a predicted molecular weight. Effects of pH indicated that the $\beta$-glucosidase showed similar activity using $\alpha$-pNPG($\rho$-nitrophenyl-$\alpha$-D-glucopyranoside), $\beta$-pNPG($\rho$-nitrophenyl-$\beta$-D-glucopyranoside), and $\beta$-pNPF($\rho$-nitrophenyl-$\beta$-D-fucopyranoside) at range of pH 3 to 10, and high activity using $\beta$-pNPGA ($\rho$-nitrophenyl-$\beta$-D-galactopyranoside) from pH 5 to 10, especially, 3.3 times higher activity at pH 9. Effects of temperature indicated that the $\beta$-glucosidase showed low activity using $\alpha$-pNPG, $\beta$-pNPG, and $\beta$-pNPF from $20^{\circ}C$ to $70^{\circ}C$, and increased activity using $\beta$-pNPGA from $30^{\circ}C$ to $50^{\circ}C$, 1.8 times higher activity at $50^{\circ}C$ than at $30^{\circ}C$. According to activity determination of other substrates, the enzyme was active on daidzin, genistin, and glycitin, inactive on esculin and apigenin-7-glucose. The EDTA and DTT as reducing agents inhibited $\beta$-glucosidase activity, but SDS and mercaptoethanol did not inhibit. Monovalent or divalent metal ions such as $MnSO_4$, $CaCl_2$, KCl, and $MgSO_4$ did not inhibited $\beta$-glucosidase activity. $CuSO_4$ and NaCl showed low inhibition, and $ZnSO_4$ inhibited 3.3 times higher than control.

• Korean Journal of Environmental Agriculture
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• v.35 no.3
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• pp.166-174
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• 2016

BACKGROUND: The current study developed a monitoring method of 6 veterinary antibiotics (amoxicillin, ampicillin, enrofloxacin, tetracycline, chlortetracycline, oxytetracycline) in agricultural soils using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in positive electrospray ionization mode.METHODS AND RESULTS: Sample preparation was carried out using acidic acetonitrile and citrate salts followed by purification with dispersive solid phase extraction (d-SPE). Separation on Eclipse Plus C₁₈ column was conducted in gradient of the mobile phase, 0.1% formic acid and 5 mM ammonium formate in methanol (A) and 0.1% formic acid and 5 mM ammonium formate in distilled water (B). The linearity of the matrix-matched calibrations expressed as the coefficient of determination was good with R²≥0.9900. The limit of quantifications (LOQs) ranged from 0.5 to 10 μg/kg for all analytes. Analysis of 51 agricultural soil samples taken in the Republic of Korea revealed concentrations less than 1.9 μg/kg for enrofloxacin, 75.5 μg/kg for chlortetracycline.CONCLUSION: The method was successfully applied to monitor 6 veterinary antibiotics from 51 field incurred agricultural soil samples in 17 provincial areas throughout the Republic of Korea. The developed method was simple, easy, and versatile and can be used for monitoring various veterinary antibiotics in soil.

• Journal of Microbiology
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• v.44 no.4
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• pp.423-431
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• 2006

Among 53 Acinetobacter baumannii isolates collected in 2004, nine imipenem-resistant isolates were obtained from clinical specimens taken from patients hospitalized in Busan, Korea. Nine carbapenemase-producing isolates were further investigated in order to determine the mechanisms underlying resistance. These isolates were then analyzed via antibiotic susceptibility testing, microbiological tests of carbapenemase activity, pI determination, transconjugation test, enterobacterial repetitive consensus (ERIC)-PCR, and DNA sequencing. One outbreak involved seven cases of infection by A. baumannii producing OXA-23 ${\beta}-lactamase$, and was found to have been caused by a single ERIC-PCR clone. During the study period, the other outbreak involved two cases of infection by A. baumannii producing IMP-1 ${\beta}-lactamase$. The two clones, one from each of the outbreaks, were characterized via a modified cloverleaf synergy test and an EDTA-disk synergy test. The isoelectric focusing of the crude bacterial extracts detected nitrocefin-positive bands with pI values of 6.65 (OXA-23) and 9.0 (IMP-1). The PCR amplification and characterization of the amplicons via direct sequencing showed that the clonal isolates harbored $bla_{IMP-1}$ or $bla_{oxA-23}$ determinants. The two clones were characterized by a multidrug resistance phenotype that remained unaltered throughout the outbreak. This resistance encompassed penicillins, extended-spectrum cephalosporins, carbapenems, monobactams, and aminoglycosides. These results appear to show that the imipenem resistance observed among nine Korean A. baumannii isolates could be attributed to the spread of an IMP-lor OXA-23-producing clone. Our microbiological test of carbapenemase activity is a simple method for the screening of clinical isolates producing class D carbapenemase and/or class B $metallo-{\beta}-lactamase$, in order both to determine their clinical impact and to prevent further spread.