Towards electrochromic ammonium ion sensors

Proceedings of The 1st International Electronic Conference on Biosensors

Ammonium ion (NH4+) is one of the indicators of water quality. High ammonium concentration [NH4+] in water can cause eutrophication, affect aquatic biota, and cause cell death in the central nervous system of human beings. However, current ion-selective electrodes used for water-quality monitoring are bulky, require frequent calibration owing to membrane fouling, and cannot be integrated into mobile sensor platforms. We fabricated an all-solid-state ion-selective electrode (AS-NISE) for ammonium ion using a two-step process. The first step is electropolymerization deposition on the electrode using a solution of 3,4-ethylenedioxythiophene (EDOT), sodium polystyrene sulfonate (NaPSS), and lithium perchlorate (LiCLO4), resulting in a solid-state transducer on screen-printed carbon electrodes (SPCEs), and the second is electropolymerization deposition of EDOT, NaPSS, and o-phenylenediamine (o-PD) as an ammonium ion-selective membrane (NISM) on top of the transducer. The electropolymerization deposition of the transducer and the NISM were simply achieved by cyclic voltammetry (CV) with potential from 0.0 V to 0.8 V and 50 mVs-1 scan rates. The fabricated AS-NISEcan detect [NH4+] as low as 5.7×10-5 M with a slope of 61.9 mV/decade (R2>0.99) and a linear range from 10-3 M to 1 M. These preliminary results provide an initial insight into the applicability of the simple two-steps fabrication process of NH4+ ISEs for scaling-up purposes with the ability for miniaturization and integration into a mobile sensor platform.

Journal of The Electrochemical Society, 1997

The composition of ammonium-ion sensitive membrane based on a photocurable aliphatic urethane diacrylate oligomer has been optimized. Membranes were prepared with exposure to TJV and studied in a traditional ion-selective electrode configuration with liquid inner contact. The optimum composition is found to be: urethane diacrylate (45 to 50%), hexandiol diacrylate (10%), photoinitiator (0.8 to 1.2%), plasticizer (bis(2-ethylhexyl) sebacate or di-5-nonyladipate (35 to 40%), nonactin (2%), and KTpC1PB (0.5%). The resulting ion-sensors show a sensitivity of 55.5 mV/decade, a range of linear response from 1 to 4.5 iO mol/liter of NH4C1, a limit of detection around 10' mol/liter, and good selectivity in the presence of potassium ions. Introduction of 7% PVC into the membrane formulation gives a possibility to enhance the sensitivity up to 58 mV/decade but prevents application of photolithography for membrane patterning in case of ion sensitive field effect transistor-based sensors. The developed polymer composition was used to prepare ISFETbased ammonium sensors with the membrane deposited and structured on a wafer level.

Journal of Industrial Technology, 2015

RINGKASAN: Satu alat pengimbas biosensor mudah alih tanpa wayar telah dibangunkan untuk mengesan dan mengukur kandungan ammonium di dalam kolam akuakultur. Pengimbas ini dibangunkan menggunakan kaedah tindakbalas enzim glutamate dehydrogenase (GLDH) dan diaphorase (Dph) yang dapat memberi respon kepada kehadiran ammonium menggunakan NADH sebagai pengantara (mediator), apabila terdedah kepada LED lampu hijau pada panjang gelombang (wavelength) 565 nm. Kepekatan ammonia yang diukur adalah berkadar terus dengan pengurangan kepekatan NADH di dalam larutan. Pengimbas biosensor ini akan mengukur keamatan cahaya (Io & Is), memproses signal dan seterusnya mempamerkan keputusan kepekatan ammonium pada telefon pintar melalui komunikasi Bluetooth. Perbandingan graf penentukuran linear di antara pengimbas biosensor dengan kaedah makmal mengunakan spektrofotometer dalam pengesanan ammonia menunjukkan bacaan ketepatan dan R 2 pada pengimbas biosensor adalah lebih baik berbanding dengan kaedah spektrofotometer.

Sensors and Actuators B: Chemical, 2001

A novel method for sensing potassium ions in aqueous solutions is presented. This method is based on the Prussian blue (PB) modi®ed tin oxide (TO) electrode. Thin ®lms of PB (KFeFe(CN) 6), deposited onto transparent TO substrate, are reduced to Everitt's salt (ES, or K 2 FeFe(CN) 6) in solutions containing potassium ions. Using an in situ measurement of the absorbance changes in PB thin ®lm while applying different reductive potentials to the electrode, the PB mole fraction within the thin ®lm, x, can be obtained for solutions containing various concentrations of potassium ions. By applying either the theory of regular solution (0:25 < x < 1) or the Margules equation (0 < x < 0:25) to the Nernst equation, one can construct a special function, which depends mainly on the PB mole fraction and the interaction parameters involved. This sensing method, which eliminates the need for pre-conditioning the electrode to a ®xed potential, as proposed previously by other researchers, is based on a linear log±log plot of this special function against the potassium ion concentrations. Such a relationship was observed when the K concentrations ranged from 3:3 Â 10 À4 M to 1.0 M. The interferences of Na and Ba 2 on the K sensing are also studied.

Monatshefte für Chemie - Chemical Monthly, 2017

An ammonium ion biosensor was constructed using a screen-printed carbon electrode based on alanine dehydrogenase immobilized on core shell Fe 3 O 4 @Au nanoparticles which were attached to the electrode surface by an external magnet. The amperometric current response in a flow injection analysis system depending on the oxidation of NADPH was proportional to the amount of ammonium ion consumed during the catalytic reaction of the alanine dehydrogenase enzyme. The designed biosensor was evaluated with a linear response range from 5 to 250 mM with a sensitivity of 0.2 lA mM-1 cm-2 , a detection limit of 2.1 mM, and a quantification limit of 6.3 mM. Moreover, the repeatability (ten measurements) and the reproducibility (three sensors) were estimated as 2.6%RSD and 3.0%RSD, respectively. The proposed biosensor was applied successfully to the determination of ammonium ion concentration in concentrated latex samples. Graphical abstract Keywords Biosensor Á Electrochemistry Á Enzymes Á Ammonium ion Á Fe 3 O 4 @Au particles Á Flow injection analysis & Anchalee Samphao

Journal of Colloid and Interface Science, 2001

Ammonium chlorides immobilized on silica gel, SA + /Cl − and SE + /Cl − , were obtained from silica previously modified with 3-aminopropyltriethoxysilane and N-[3-(trimethoxysilyl)propyl]ethylenediamine, respectively. Both materials showed potential use as an anion exchanger: they are thermically stable (up to 413 K), achieve equilibrium rapidly in the presence of suitable exchanger ions, and are easily recovered. The exchange capacities observed for SA + /Cl − and SE + /Cl − are 0.70 and 1.19 mmol Cl − g −1 , respectively. Through the exchange isotherms and competitive Cl −-X − exchange (X − = F − , Br − , I − , N − 3 , NO − 3 , SCN − , ClO − 4) it was observed that: (i) SE + /Cl − exchanges the counterion Cl − more easily than SA + /Cl − ; (ii) SA + /Cl − presents higher selectivity than SE + /Cl − ; and (iii) SA + /Cl − presents high affinity for ClO − 4. Because of these two latter properties presented by the SA + /Cl − , the derivative SA + /ClO − 4 was used as a potentiometric sensor for this anion, prepared from the supported material on a mixture of graphite powder with epoxy resin. The electrode showed a nernstian behavior and a limit of response of 0.13 mmol L −1. Potentiometric selectivity coefficients, K pot A,B , were obtained for some interfering anions, and the following interference order was observed: F − > SCN − > NO − 3 > Br − > Cl − > CH 3 COO −. The electrode showed fast and stable responses and was useful for approximately 200 measures.

Biosensors and Bioelectronics, 2005

Being one of the most commonly used electrochemical mediators for analytical applications, Prussian Blue has found a wide use in the biosensor field during the last years. Its particular characteristic of catalysing hydrogen peroxide reduction has been applied in the construction of a large number of oxidase enzyme-based biosensors for clinical, environmental and food analysis.

Chemical Papers, 2017

The effect of long-chain quaternary ammonium salts' exchange center steric accessibility and presence of a neutral anion carrier, 4-(trifluoroacetyl)benzoic acid heptyl ester, upon analytical characteristics of ion-selective electrodes reversible to molybdate, tungstate, sulfate, hydrogen phosphate, sulfite, carbonate and thiosulfate anions, has been studied. When the most sterically hindered quaternary ammonium salts, trinonyl octadecyl ammonium bromide, is replaced by one of the salts with the accessible exchange center, the selectivity is altered, the magnitude of the selectivity coefficient change being determined by the nature of the interfering ion. Thus, for carbonate-and sulfate-selective ISEs with hydrophobic thiocyanate ions as interference, the effect achieved is 6-8 orders of magnitude, while with nitrate ions as interference it is 3.4-5.7 orders, and for such hydrophilic interference ions as sulfate, chloride and oxalate, it is even less. Replacing trinonyl octadecyl ammonium bromide with a sterically accessible ammonium salt improves lower detection limit generally by 1-2 orders, while for sulfite and thiosulfate ISEs the effect is only 0.3-0.95 orders. The procedures for determination of sulfate, sulfite and carbonate ions in real objects (mineral water, dried fruits) have been proposed. They are simple, reasonably accurate, require only widely available equipment and can be recommended for use in chemical and food industries.

The Analyst, 2020

An overview of ionophore-based electrodes for ammonium sensing critically analyzing contributions in the last 20 years and with focus in analytical applications.

Organic Letters, 2005

Electrooptical sensors consisting of a conjugated chromophore undergoing a change in color and a redox-active moiety such as quinone fused to the chromophore were synthesized. Strong changes in colorimetric and electrochemical properties were observed in the presence of inorganic anions. A unique anion-specific response was observed for fluoride, pyrophosphate, and acetate. DFT (B3LYP/6-31G*) calculations performed for both "on/off" states of a sensor-fluoride model are in good agreement with the observed electrochemical and spectroscopic data.