Few biosensors are reported for usage in combination with the organic solvent due to their negative impact on the enzymes. The usage of ternary water-organic solvent mixtures in combination with acetylcholinesterase biosensors allows to increase the useable total content of organic solvents with minimum negative effects to a higher content in comparison with a single organic solvent in water. The combination of acetonitrile/ethanol/water has a smaller negative effect on both enzyme activity and inhibition by insecticides in comparison with acetonitrile/methanol/water mixtures. The insecticides were eluted from solid-phase extraction (SPE) columns with a binary mixture of organic solvents acetonitrile/ethanol in 1/3 ratio and subsequently analysed with an acetylcholinesterase biosensor and the optimum total content of organic solvents of 12%. The analytical method allows the analysis of complex samples with improved selectivity and at improved limits of detection for chlorpyrifos-oxon and carbofuran analysis in river waters and soil samples. The usage of mixtures of organic solvents in combination with enzymes is an interesting approach that allows working with a higher total content of organic solvents than each individual solvent.
Keywords: Enzymatic biosensor; Enzyme inhibition; Organic solvents mixture; Solid-phase extraction.
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