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1

Meldola’s Blue - doped titania sol-gel sensor for NADH determination

100%

Adamski J., Kochana J.

Open Chemistry

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2011

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vol. 9

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issue 1

185-191

EN

Titania layers obtained by a sol-gel technique doped with redox mediator, Meldola’s Blue, were employed for construction of a new NADH senor. Optimization of preparation process as well as experimental conditions affecting the response of the sensor were examined. Under optimal conditions NADH could be determined in the wide linear range from 90 to 2300 µM with detection limit 12 µM and a high sensitivity 12.5 nA µM−1. The usefulness of developed sensor was preliminarily checked in determination of NADH forming during enzymatic oxidation of ethanol catalyzed by alcohol dehydrogenase (ADH). [...]

2

Detection of NADH and ethanol at a graphite electrode modified with titania sol-gel/Meldola’s Blue/MWCNT/Nafion nanocomposite film

100%

Kochana J., Adamski J.

Open Chemistry

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2012

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vol. 10

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issue 1

224-231

EN

For electrocatalytic determination of NADH, a graphite electrode modified with titania sol-gel/Meldola’s Blue/MWCNT/Nafion nanocomposite was proposed. The composition of the matrix film was optimised in terms of the content of carbon nanotubes and Nafion. Incorporation of a redox mediator, Meldola’s Blue, into the nanocomposite film enabled electrocatalytic determination of NADH at a low potential, −50 mV. For determination of ethanol, alcohol dehydrogenase (ADH) was immobilized into the matrix layer. Experimental conditions affecting the biosensor response were examined, including enzyme loading, temperature of measurement and pH of background electrolyte. Assessments of the analytical characteristics of the biosensor were performed with respect to sensitivity, limit of detection, operational stability, repeatability and reproducibility. The proposed biosensor showed electrocatalytic activity toward oxidation of ethanol with sensitivity of 2.24 µA L mmol−1, linear range from 0.05 to 1.1 mmol L−1, and limit of detection of 25 µmol L−1. The apparent Michaelis-Menten constant was 1.24 mmol L−1, indicating a high biological affinity of ADH/titania sol-gel/Meldola’s Blue/MWCNT/Nafion electrode for ethanol. The developed biosensor was tested in determinations of ethanol content in alcoholic beverages.

3

A Critical View on the Phenol Index as a Measure of Phenol Compounds Content in Waters. Application of a Biosensor

81%

Kochana J., Adamski J., Parczewski A.

Ecological Chemistry and Engineering S

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2012

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vol. 19

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issue 3

383-391

EN

Phenol index is considered as an important indicator of water purity and quality. Usually phenol index is determined by a spectrophotometric method the calibration being based on phenol standards. Unfortunately, the absorptivities of different phenols compounds differ from each other. This leads to significant uncertainty concerning content of phenols in water. It is shown that the same shortage of the phenol index appears also if it is determined using an amperometric biosensor based on tyrosinase. The sensitivity of the biosensor response to four phenol compounds: phenol, catechol, 3-cresol and 4-chlorophenol was examined, as well as possible interactions between phenols, according to 24 factorial experiment. It was proved that individual phenols affect phenol index independently from each other, ie no significant interaction between phenols was detected. However, sensitivity of the biosensor to different phenols is not the same. Relationship between phenol index and concentrations of phenols in water is discussed.

PL

Indeks fenolowy jest ważnym wskaźnikiem czystości i jakości wody. Oznacza się go zwykle metodami spektrofotometrycznymi z 4-aminoantypiryną, stosując fenol jako wzorzec. Ponieważ współczynniki absorpcji różnych związków fenolowych różnią się, wyznaczona wartość indeksu fenolowego obarczona jest znaczną niepewnością. Podobny efekt występuje, gdy indeks fenolowy oznaczany jest przy użyciu biosensora amperometrycznego opartego na tyrozynazie. W pracy wyznaczono czułości biosensora w stosunku do czterech związków fenolowych: fenolu, katecholu, 3-krezolu oraz 4-chlorofenolu oraz zbadano możliwe interakcje pomiędzy fenolami. Doświadczenia prowadzono według planów czynnikowych 24. Wykazano, że poszczególne fenole wpływają na indeks fenolowy niezależnie od siebie, tzn. nie stwierdzono istotnych interakcji pomiędzy fenolami. Jednak czułość biosensora jest różna w stosunku do różnych fenoli. Przedyskutowano zależność pomiędzy indeksem fenolowym a stężeniami fenoli w wodzie.

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2 Open Chemistry

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3 Adamski J.

3 Kochana J.

1 Parczewski A.

Meldola’s Blue - doped titania sol-gel sensor for NADH determination

Detection of NADH and ethanol at a graphite electrode modified with titania sol-gel/Meldola’s Blue/MWCNT/Nafion nanocomposite film

A Critical View on the Phenol Index as a Measure of Phenol Compounds Content in Waters. Application of a Biosensor