Composites of chitosan polyelectrolyte complexes with cyclodextrins were used for selective recognition of atenolol enantiomers in pharmaceuticals and human urine.

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The electrochemical and analytical characteristics of enantioselective sensors based on glassy carbon electrodes modified by chelate complexes (bis(L-phenylalaninate) copper(II), glycinato-L-phenylalaninate copper(II), tris(L-phenylalaninate) cobalt(II), bis(L-phenylalaninate) zinc) are studied. It is found that the most promising sensor for determining tryptophan enantiomers is the sensor modified by copper(II) (bis)L-phenylalaninate. In determining tryptophan enantiomers, this sensor provides a linear concentration range from 6.25 × 10 -7 to 0.5 × 10 -3 M for L-tryptophan and from 5 × 10 -6 to 0.5 × 10 -3 M for D-tryptophan. The sensor is more sensitive to L-tryptophan. The proposed sensor was used for the recognition and determination of tryptophan enantiomers in human urine and plasma samples, and also in a mixture of enantiomers. The statistical assessment of the results of determinations by the spiked-found method indicates the absence of a significant systematic error.

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