Solid-contact pH-selective electrode using multi-walled carbon nanotubes

Abstract

Multi-walled carbon nanotubes (MWCNT) are shown to be efficient transducers of the ionic-to-electronic current. This enables the development of a new solid-contact pH-selective electrode that is based on the deposition of a 35-microm thick layer of MWCNT between the acrylic ion-selective membrane and the glassy carbon rod used as the electrical conductor. The ion-selective membrane was prepared by incorporating tridodecylamine as the ionophore, potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate as the lipophilic additive in a polymerized methylmethacrylate and an n-butyl acrylate matrix. The potentiometric response shows Nernstian behaviour and a linear dynamic range between 2.89 and 9.90 pH values. The response time for this electrode was less than 10 s throughout the whole working range. The electrode shows a high selectivity towards interfering ions. Electrochemical impedance spectroscopy and chronopotentiometry techniques were used to characterise the electrochemical behaviour and the stability of the carbon-nanotube-based ion-selective electrodes.

Applications of nanomaterials in potentiometric sensors

“…These properties are favorable for acting as solid contacts, as demonstrated by Rius and co-workers in developing a series of solid-state ISEs for ions -K + [21], choline [22], Ca 2+ [23], pH [24] and…”

BAZI İÇECEKLERDE TİTRASYON ASİTLİĞİNİN TAYİNİ İÇİN ZOFENOPRİL KALSİYUMA DAYANAN pH ELEKTROT YAPIMI

“…Bu amaçla, portakal ve elma suyu, gazl› içecek, bira, k›rm›z› flarap ve sirke numuneleri ulusal/uluslararas› standartlarda belirtilen yöntemlere göre haz›rlanm›fl ve indikatör elektrot olarak yeni gelifltirilen pH elektrodun kullan›lmas›yla ayarl› NaOH ile titre edilmifltir. fiekil 3 ZFNCa'a dayanan PVC membran pH elektrodun kalibrasyon e¤risi Figure 3 The calibration graph of the PVC membrane pH electrode based on ZFNCa Literatürdeki eflde¤erleriyle karfl›laflt›r›ld›¤›nda, ZFNCa kullan›larak haz›rlanan PVC membran pH elektrodun, yüksek seçicilik özellikleri ve uzun ömrü aç›s›ndan üstün (10, 12, 20, 22, 24, 25, 30-, 32); tekrarlanabilirlik, tekrar üretilebilirlik aç›s›ndan ise yar›flabilir nitelikte oldu¤u görülmüfltür (6,7,11,34). Önerilen elektrodun haz›rlanmas›nda iyonofor olarak kullan›lan ZFNCa'un biyouyumlu olmas›, kalite kontroller s›ras›nda, g›da numunelerinde do¤rudan pH ölçümü için bu elektrodun kullan›labilir nitelikte oldu¤unu düflündürmüfltür.…”

“…Ayr›ca, mikroelektrot olarak üretilmeye ve in situ (yerinde) çal›flmalarda kullan›lmaya uygun de¤ildirler (4,5). Bu nedenle, son y›llarda, kat›-temasl› elektrotlar (SCE'lar) (6)(7)(8)(9)(10)(11)(12), kaplanm›fl tel elektrotlar (CWE'lar) (13,14), alan etkili transistörler (FET'ler) (15,16), nano çubuk elektrotlar (17,18) ve polimerik membran elektrotlar (PME'lar) (19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33) (10,27,28), aminler (11)(12)(13)24), pillar [5]arenler (29), ve kaliks [4]arenler (30)(31)(32)(33) gösterilebilir. Literatür incelendi¤inde, baz› ilaç etken maddelerinin voltametrik/amperometrik sensörlerde duyarl›l›k sa¤lamak amac›yla kullan›ld›¤› (36, 37), ancak, pH duyarl› potansiyometrik PVC membran elektrot haz›rlanmas›nda iyonofor olarak kullan›lmad›¤› tespit edilmifltir.…”

Electroanalytical Sensor Technology

“…Within the field of potentiometric sensors and specifically the design of contacts for all solid state sensors, the potential of nanomaterials such as CNTs and fullerenes has been rigorously examined. Rius et al [132][133][134][135] described the development of many sensors based on SW-and/or MW-CNT sensors, including an all-solid-state potassium ion-selective membrane electrode and a perchlorate selective membrane electrode using a MWCNT-derived solid contact.…”