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Hong, Young-Ki,Cha, Geun-Sig,Shin, Doo-Soon,Nam, Hak-Hyun Korean Chemical Society 1994 Bulletin of the Korean Chemical Society Vol.15 No.10
The polymer matrix effect on the selectivity, response rate and reproducibility for coextraction type anion-selective optode membranes were investigated with DOA-plasticized PVC, PVC/hydroxylated PVC, PU/hydroxylated PVC and DOS-plasticized CTA matrices. Optode membranes were prepared with TDMACl and ETH2412 dissolved in one of the four solvent polymeric matrices. The PU/hydroxylated PVC and PVC-based membranes have almost the same selectivity coefficients, while the CTA-based membrane is more selective toward lipophilic anions. The membrane with PU/hydroxylated PVC adhered strongly to a glass surface, and showed highly reproducible and relatively rapid response. Very poor adhesion of PVC/hydroxylated PVC and CTA-based membranes limited the usability of those membranes as sensor components. Based on these results, and considering the biocompatibility for clinical samples, the optode made with PU/hydroxylated PVC was applied to determine the thiocyanate ion in human saliva. The results obtained with this simple device were comparable to those with rather complicated ISE methods.
Coextraction형 음이온선택성 광센서를 이용한 인체 타액 내의 티오시안염 양의 결정
남학현,차근식,한상현 光云大學校 1994 論文集 Vol.23 No.-
동시추출형 음이온선택성 광센서는 티오시안삼염과 같은 지용성 음이온에 대하여 선택적으로 감응을 한다. 이러한 광센서는 음이온을 막 안으로 끌어들일 수 있는 양이온성의 4차암모니움염(TDMACI)과 전하균형을 맞추며 색의 변화를 수반하는 음이온성 pH 지시약(ETH2412)으로 구성되어 있다. 감응화학물질들은 DOA 가소제와 PU 고분자의 혼합물에 녹여서 성형한 것이다. 이 광센서 막의 선택성향은 음이온의 수화에너지 순서인 Hoffmeister 계열(CIO?> SCN?> I?> NO?> Br?> C1?> HCO?> CH?COO?> SO? ∼ HPO??)을 따른다. 본 논문은 이러한 광센서를 이용하여 인체의 타액에 함유되어 있는 티오시안산염의 양을 결정하였다. 고분자 지지체의 성분은 PVC와 거의 같은 선택계수를 갖지만 감응속도나 재현성은 훨씬 뛰어나고 생체시료에 대한 적합성이 우수한 PU/hydroxylated PVC이었다. 티오시안산염은 독성의 시안산염이 대사된 결과 생성되는 부산물이며, 이 물질의 양을 측정하면 흡연의 영향을 얼마나 받았는지 알 수 있는 척도 자료가 된다. 10명의 타액을 이 광센서로 검출한 결과는 비교적 복잡한 장치를 써야하는 이온선택성 방법으로 얻은 결과와 견줄만한 것이었다.
Effect of Surfactants on the Electrochemical Performance of Cation-Selective Membrane Electrodes
Oh, Hyun-Joon,Cha, Geun-Sig,Nam, Hak-hyun Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.1
We examined the effect of polyether-type nonionic surfactants (Brij 35, Triton X-100, Tween 20 and Tween 80) on the potentiometric properties of sodium-, potassium- and calcium-selective membranes which are prepared with widely used ionophores and four kinds of polymer matrices [poly(vinyl chloride) (PVC), polyurethane (PU), PVC/PU blend, and silicone rubber (SR)]. It was found that the PVC-based membranes, which provide the best performance among all other matrix-based membranes in the absence of nonionic surfactants, exhibited larger change in their potentiometric properties when nonionic surfactants are added to the sample solution. On the other hand, the sodium-selective SR-based membrane with calix[4]arene, potassium-selective PVC/PU- or SR-based membrane with valinomycin, and the calcium-selective SR-based membrane with ETH 1001 provide almost identical analytical performance in the presence and absence of Tween 20 or Tween 80 surfactants. The origin of nonionic surfactants effect was also investigated by interpreting the experimental results obtained with various matrices and ionophores. The results suggest that the nonionic surfactant extracted into the membrane phase unselectively form complexes with the primary and interfering ions, resulting in increased background potential and lower binding ability for the ionophore. Such effects should result in deteriorated detection limits, reduced response slopes and lower selectivity for the primary ions.
Electroanalytical Applications Based on Carbon Nanotube/Prussian Blue Screen-printable Composite
Jun Ho Shim,Jae Seon Lee,Geun Sig Cha,Hakhyun Nam 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.6
A single step fabrication process of carbon nanotube/Prussian Blue (CNT/PB) paste electrodes based on screen printing technology has been studied as an amperometric sensor for the determination of hydrogen peroxide and free chlorine. Compared to the classical carbon paste (CP) electrode, the CNT paste electrode greatly enhanced the response in the presence of hydrogen peroxide due to the electrocatalytic activity of the CNT. Based on the CNT/binder paste,PB was also incorporated into a network of CNT paste and characterized. The best electroanalytical properties of PB-mixed sensors to hydrogen peroxide were obtained with PB ratio of 10 wt % composition, which showed fast response time (t90 ≤ 5 s; 0.2 - 0.3 mM), low detection limit of 1.0 μM, good linear response in the range from 5.0 ×10‒5 - 1.0 × 10‒3 mol L‒1 (r2 = 0.9998), and high sensitivity of ‒8.21 μA mM‒1. In order to confirm the enhanced electrochemical properties of CNT/PB electrode, the sensor was further applied for the determination of chlorine in water, which exhibited a linear response behavior in the range of 50 - 2000 ppb for chlorine with a slope of 1.10 μA ppm‒1 (r2 = 9971).
Electroanalytical Applications Based on Carbon Nanotube/Prussian Blue Screen-printable Composite
Shim, Jun-Ho,Lee, Jae-Seon,Cha, Geun-Sig,Nam, Hak-Hyun Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.6
A single step fabrication process of carbon nanotube/Prussian Blue (CNT/PB) paste electrodes based on screen printing technology has been studied as an amperometric sensor for the determination of hydrogen peroxide and free chlorine. Compared to the classical carbon paste (CP) electrode, the CNT paste electrode greatly enhanced the response in the presence of hydrogen peroxide due to the electrocatalytic activity of the CNT. Based on the CNT/binder paste, PB was also incorporated into a network of CNT paste and characterized. The best electroanalytical properties of PB-mixed sensors to hydrogen peroxide were obtained with PB ratio of 10 wt % composition, which showed fast response time ($t_{90}{\leq}5$ s; 0.2 - 0.3 mM), low detection limit of 1.0 ${\mu}M$, good linear response in the range from $5.0{\times}10^{-5}$ - $1.0{\times}10^{-3}$ mol $L^{-1}$ ($r^2$ = 0.9998), and high sensitivity of -8.21 ${\mu}AmM^{-1}$. In order to confirm the enhanced electrochemical properties of CNT/PB electrode, the sensor was further applied for the determination of chlorine in water, which exhibited a linear response behavior in the range of 50 - 2000 ppb for chlorine with a slope of 1.10 ${\mu}Appm^{-1}$ ($r^2$ = 9971).
ISFET-Based Differential pCO₂Sensors Employing a Low Resistance Gas Permeable Membrane
Shin, Jae Ho,Nam, Hakhuyn,Cha, Geun Sig,Kim, Chol,Ha, Byoung Ju 경북대학교 센서기술연구소 1995 센서技術學術大會論文集 Vol.6 No.1
A new type of ISFET-based differential pCO_(2) sensor system is devised by employing a low resistance gas permeable membrane. Both the pCO_(2) FET and the reference FET (REFET) are made by coating the FET surface with an RTV silicone rubber film doped with valinomycin. The pCO_(2)FET is covered with a hydrogel-based recipient layer inside the gas permeable RTV membrane, but the REFET without the hydrogel layer. Because of low resistance of the gas permeable membrane, the reference electrode can be placed outside as a common reference for both FETs. Output signals from the pCO_(2) FET and the REFET are measured against the common reference, and a difference of these two signals is measured through a differential amplifier: therefore, calibration drifts of the two identical base ISFETs, caused by their thermal sensitivity, cancel out.