Aim. The analysis of toxicity of different water samples with the multibiosensor developed earlier. Methods. The potentiometric multibiosensor with several immobilized enzymes as bioselective elements and the matrix of pH-sensitive field effect transistors as transducers of the biochemical signal into the electric one was applied for the analysis. Results. The bioselective elements of the multibiosensor were developed using acetylcholinesterase, butyryl- cholinesterase, urease, glucose oxidase, and three-enzyme system (invertase, mutarotase, glucose oxidase). The measurement of toxic compounds in water samples of different origin was performed using the constructed sensor. The results obtained were compared with those obtained by the conventional methods of toxic agent’s analysis (atomic absorption spectrometry, thin-film chroma- tography, and atomic absorbic analyser of mercury). Conclusion. A strong conformity between the results obtained with the multibiosensor and traditional methods has been shown

The operation of highly sensitive and selective multibiosensor based on several immobilized enzymes as bioselective elements and a matrix of pH-sensitive field effect transistors as transducers of the biochemical signal into electric one has been investigated. To develop bioselective elements of multibiosensor, the enzymes highly sensitive to toxins, such as acetylcholinesterase, butyrylcholinesterase, urease, glucose oxidase, and a three-enzyme system (invertase, mutarotase, glucose oxidase), were used. Optimal substrates concentrations for inhibitory analysis were determined to be: 10 mM acetylcholine, 5 mM butyrylcholine, 5 mM urea, 5 mM sucrose, and 2 mM glucose. It was shown that there was practically no cross-influence of the substrates on the used enzyme systems. Time of incubation of the multibiosensor in solutions with toxic compounds was 20 min. The inhibitory influence of separate toxins and their mixtures on bioselective elements of multibiosensors was studied.

The investigation presents the development of highly sensitive and selective multibiosensor based on different immobilized enzymes as bioselective elements and the matrix of ion-selective field effect transistors as transducers. To develop bioselective elements of multibiosensor, such enzymes as acetylcholinesterase, butyrylcholin esterase, urease, glucose oxidase, and three-enzyme system (invertase, mutarotase, glucose oxidase) were used. The bioselective elements obtained were shown to demonstrate high sensitivity to corresponding substrates in direct enzymatic analysis, which lasted 10 min. Dynamic range of substrate determination (0.1 mM-1.5-10 mM) was shown to depend on an enzymatic system and differ specifically in the upper detection limit. The dependence of multibiosensor response on pH, ionic strength, and buffer capacity was investigated; optimal conditions for simultaneous operation of all bioselective elements of the multibiosensor were selected; the data on cross-influence of substrates for all the enzymes used were obtained. The developed multi-analyzer was shown to demonstrate sufficient signal reproducibility.

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