• Bulletin of the Korean Chemical Society
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• 제34권9호
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• pp.2577-2582
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• 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.

• Bulletin of the Korean Chemical Society
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• 제25권2호
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• pp.172-176
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• 2004

A highly selective membrane electrode based on1,3,5-triphenylpyrylium perchlorate (TPPP) is presented. The proposed electrode shows very good selectivity for sulfate ions over a wide variety of common inorganic and organic anions. The sensor displays a nice Nernstian slope of -29.7 mV per decade. The working concentration ranges of the electrode is 1.0{\times}10^{-1}-6.3{\times}10^{-6} $M with a detection limit of $4.0{\times}10^{-6}$ M (480 ng per mL). The response time of the sensor in whole concentration ranges is very short (< 6 s). The response of the sensor is independent on the pH range of 2.5-9.5. The best performance was obtained with a membrane composition of 32% PVC, 59% benzyl acetate, 5% TPPP and 4% hexadecyltrimethylammonium bromide. It was successfully used as an indicator electrode for titration of sulfate ions with barium ions. The electrode was also applied for determination of salbutamol sulfate and paramomycine sulfate.

• Bulletin of the Korean Chemical Society
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• 제35권11호
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• pp.3175-3180
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• 2014

A potentiometric sensor based on the 1-benzyl-3-(4-nitrophenyl) thio-urea was synthesized and tested as an ionophore in PVC based membrane sensor towards $SCN^-$ ions. This membrane exhibits a linear stable response over a wide concentration range ($1.0{\times}10^{-5}$ to $1.0{\times}10^{-2}M$) with a slope of -59.2 mV/dec., a detection limit of ${\log}[SCN^-]=-5.05$, and a selectivity coefficient for thiocyanate against perchlorate anion of ${\log}K^{pot}_{SCN^-j}=-0.133$. The selectivity series of the membrane is as follows: $SCN^-$ > $ClO_4{^-}$ > $I^-$ > $NO_3{^-}$ > $HSO_3{^-}$ > $Cl^-$ > $HSO_4{^-}$ > $F^-$ > $CH_3COO^-$ > $HCO_3{^-}$ > $Br^-$ > $H_2PO_4{^-}$ > $SO{_3}^{2-}$ > $SO{_4}^{2-}$ > $CO{_3}^{2-}$. The proposed electrode showed good selectivity and a good response for the $SCN^-$ ion over a wide variety of other anions in pH 6.0 buffer solutions and has a fast response time of about < 5s. The influences of the membrane by pH, ionophore, and plasticizer were studied.