• Bulletin of the Korean Chemical Society
• /
• v.10 no.2
• /
• pp.196-200
• /
• 1989

Some s-triazine herbicides, namely simazine, atrazine, and propazine present as trace components in a complex mixture were analyzed by GC/MS and GC/MS/MS methods. Even though monitoring the molecular ions was the best in terms of sensitivity, adequate analysis could not be done when interfering species were present. When doubly charged ions which appeared at characteristic m/z values were monitored, chromatograms were rather free from interference. More importantly, selected reaction monitoring was found to provide a selective means of detection with general applicability.

• Journal of Environmental Science International
• /
• v.32 no.11
• /
• pp.757-765
• /
• 2023

Lead, a heavy metal widely employed in various industries, continues to pose a threat to both human health and the environment. Therefore, the development of a sensor capable of rapidly and accurately detecting lead(II) ions in real-time at contaminated sites is crucial. In this study, we have engineered a fluorescent sensor with the ability to efficiently detect lead(II) ions under actual environmental conditions, including tap water and freshwater. The compound, tetraphenylethylene carboxylic acid derivative (TPE-COOH), exhibits high selectivity and sensitivity toward lead(II) ions in aqueous solution, where the interaction between TPE-COOH and lead(II) ions leads to its aggregation, thus triggering a fluorescence "turn-on" based on the aggregation-induced emission (AIE) mechanism. Impressively, compound TPE-COOH proficiently detects lead(II) ions within a range of 30 to 100 𝜇M in tap water and freshwater, even in the presence of various interfering substances.

• Journal of the Korean institute of surface engineering
• /
• v.29 no.6
• /
• pp.678-682
• /
• 1996

The plasma-deposited polymer thin films at platinum surface were investigated as materials blocking access of chloride ions to the platinum surface and preventing their interference with the Nernstian responce of platinum. In the presence of chloride ions, the pH response of a naked platinum was remarkably affected. By comparison of pH responses of coated and uncoated platinum-wire electrodes immersed in solutions with chloride ions, it was found that toluene and ethylbenzene plasma films could improve the pH response of platinum. The pH response of coated platinum electrodes may be explained by the ability of protons, by virtue of their small size, to move through the polymer matrix to the platinum surface.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.6
• /
• pp.869-872
• /
• 2004

Newly synthesized 8-hydroxyquinoline based benzothiazole derivative 2 showed a distinctive $Hg^{2+}$-selectivity over other transition metal ions in aqueous solution. The fluorescence emission at 455 nm of 2 was completely quenched upon interaction with $Hg^{2+}$ ions in dioxane-$H_2O$ system (9 : 1, v/v). The selectivity was decreased in the order of $Hg^{2+}\;>>\;Cu^{2+}\;>\;Cd^{2+}\;>\;Pb^{2+}\;{\thickapprox}\;Zn^{2+}\;{\thickapprox}\;Ni^{2+},\;and\;Hg^{2+}$ concentration dependent fluorescence quenching profile was observed in the presence of common interfering metal ions as background. The fluorescence behavior of 2 suggests that the prepared compound could be used as a fluorescent signaling subunit for the construction of new $Hg^{2+}$-sensitive ON-OFF type supramolecular switching systems.

• Carbon letters
• /
• v.26
• /
• pp.43-50
• /
• 2018

In this research, a novel and efficient quinoline thioacetamide functionalized magnetic graphene oxide composite ($GO@Fe_3O_4@QTA$) was synthesized and utilized for dispersive magnetic solid phase preconcentration of Cd(II) and Ni(II) ions in urine and various food samples. A number of diverse methods were employed for characterization of the new nanosorbent. The design of experiments approach and response surface methodology were applied to monitor and find the parameters that affect the extraction performance. After sorption and elution steps, the concentrations of target analytes were measured by employing FAAS. The highest extraction performance was achieved under the following experimental conditions: pH, 5.8; sorption time, 6.0 min; $GO@Fe_3O_4@QTA$ amount, 17 mg; 2.4 mL $1.1mol\;L^{-l}$ $HNO_3$ solution as the eluent and elution time, 13.0 min. The detection limit is 0.02 and $0.2ng\;mL^{-1}$ for Cd(II), and Ni(II) ions, respectively. The accuracy of the new method was investigated by analyzing two certified reference materials (sea food mix, Seronorm LOT NO 2525 urine powder). The interfering study revealed that there are no interferences from commonly occurring ions on the extractability of target ions. Finally, the new method was satisfactorily employed for rapid extraction and determination of target ions in urine and various food samples.

• Carbon letters
• /
• v.20
• /
• pp.10-18
• /
• 2016

Nanoporous carbon structures were synthesized by pyrolysis of grass as carbon precursor. The synthesized carbon has high surface area and pore volume. The carbon products were acid functionalized and characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Brunauer–Emmett–Teller, transmission electron microscopy, and Energy Dispersive X-ray microanalysis. Acid functionalized nanoporous carbon was explored for use in removal of toxic Cr(VI) ions from aqueous media. An adsorption study was done as a function of initial concentration, pH, contact time, temperature, and interfering ions. The experimental equilibrium data fits well to Langmuir isotherm model with maximum monolayer adsorption capacity of 35.335 mg/g. The results indicated that removal obeys a pseudo-second-order kinetic model, and that equilibrium was reached in 10 min. A desorption study was done using NaOH. The results of the present study imply that acid functionalized nanoporous carbon synthesized from grass is an efficient, renewable, cost-effective adsorbent material for removal of hexavalent chromium due to its faster removal rate and reusability.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.7
• /
• pp.1976-1980
• /
• 2010

A simple and reliable method has been developed to selectively separate and concentrate trace amounts of Fe(III) ions from water and food samples by using flame atomic absorption spectrometry. A new reagent, 5-hydroxy-4-ethyl-5,6-di-pyridin-2-yl-4,5-dihydro-2H-[1,2,4] triazine-3-thione, was synthesized and characterized by using FT-IR spectroscopy and elemental analysis. Effects of pH, concentration and volume of elution solution, sample flow rate, sample volume and interfering ions on the recovery of Fe(III) were investigated. The optimum pH was found to be 5. Eluent for quantitative elution was 10 mL of 2 M HCl. The preconcentration factor of the method, detection limit (3s/b, ${\mu}gL^{-1}$) and relative standard deviation values were found to be 25, 4.59 and 1%, respectively. In order to verify the accuracy of the method, two certified reference materials (TMDA 54.4 lake water and SRM 1568a rice flour) were analyzed. The results obtained were in good agreement with the certified values. The method was successfully applied to the determination of Fe(III) ions in water and food samples.

• Advances in environmental research
• /
• v.6 no.4
• /
• pp.301-315
• /
• 2017

An Amberlite XAD-4 resin impregnated with di(2-ethylhexyl)phosphoric acid was prepared and its adsorption-desorption behaviors with Sr(II) ions under various conditions was examined. The resin was characterized by fourier transform infrared and thermal analysis techniques. The effects contact time, temperature, pH, interfering ions and eluants were studied. Results showed that adsorption of Sr (II) well fitted with pseudo-second-order kinetic model. The equilibrium adsorption data of Sr (II) on the impregnated resin were analyzed by Jossens, Weber-van Vliet, Redlich-Peterson and Fritz-Schlunder models to find out desirable equilibrium condition. Among them, the Fritz-Schlunder model best fitted to the experimental data. The maximum sorption capacity of impregnated resin amounted to 0.45 mg/ g at pH 8.0 and $20^{\circ}C$.

• Analytical Science and Technology
• /
• v.20 no.1
• /
• pp.55-60
• /
• 2007

A sensitive technique for the determination of trace Cu(II) in various samples after the column preconcentration by adsorbing its N-benzoylphenylhydroxylamine (BPHA) onto benzophenone was developed. Several experimental conditions such as the pH of the sample solution, the amount of chelating agent, the amount of benzophenone, and the flowrate of sample solution and so forth were optimized. The interfering effects of diverse concomitant ions were investigated. Fe(III) and $CN^-$ interfered with more seriously than any other ions. However, the interference by these ions could be overcome sufficiently by adjusting the added volume of 0.01M BPHA to 10 mL. The dynamic range, the correlation coefficient ($r^2$) and the detection limit obtained by this proposed technique were 5.0~120 ng/mL, 0.9974, and 2.1 ng/mL, respectively. For validating this proposed technique, the aqueous samples (stream water, reservoir water, and wastewater), the plastic sample and the diluted brass sample were used. Recovery yields of 93~102% were obtained. These measured data were not different from ICP-MS data at 95% confidence level. This method was also validated by the rice flour CRM (normal, fortified) samples. Based on the results from the experiment, it was found that this proposed technique could be applied to the determination of Cu(II) in various real samples.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.9
• /
• pp.2577-2582
• /
• 2013

A novel stick-shaped portable sensing device featuring a microhole array interface between the polyvinylchloride-2-nitrophenyloctylether (PVC-NPOE) gel and water phase was developed for in-situ sensing of perchlorate ions in real water samples. Perchlorate sensitive sensing responses were obtained based on measuring the current changes with respect to the assisted transfer reaction of perchlorate ions by a perchlorate selective ligand namely, bis(dibenzoylmethanato)Ni(II) (Ni(DBM)2) across the polarized microhole array interface. Cyclic voltammetry was used to characterize the assisted transfer reaction of perchlorate ions by the $Ni(DBM)_2$ ligand when using the portable sensing device. The current response for the transfer of perchlorate anions by $Ni(DBM)_2$ across the micro-water/gel interface linearly increased as a function of the perchlorate ion concentration. The technique of differential pulse stripping voltammetry was also utilized to improve the sensitivity of the perchlorate anion detection down to 10 ppb. This was acquired by preconcentrating perchlorate anions in the gel layer by means of holding the ion transfer potential at 0 mV (vs. Ag/AgCl) for 30 s followed by stripping the complexed perchlorate ion with the ligand. The effect of various potential interfering anions on the perchlorate sensor was also investigated and showed an excellent selectivity over $Br^-$, $NO_2{^-}$, $NO_3{^-}$, $CO{_3}^{2^-}$, $CH_3COO^-$ and $SO{_4}^{2^-}$ ions. As a final demonstration, some regional water samples from the Sincheon river in Daegu city were analyzed and the data was verified with that of ion chromatography (IC) analysis from one of the Korean-certified water quality evaluation centers.