Search

A voltammetric sensor comprising a paste electrode made of graphitized thermal carbon black CarboblackC and nanosized zeolite MFI was developed for selective recognition and determination of tryptophan enantiomers. It was found that in determining tryptophan enantiomers, the dependence remains linear at concentrations from 5×10−5 to 1×10−3 M. The detection limits of tryptophan L‐ and D‐enantiomers were calculated to be 4.98×10−7 M and 3.20×10−7 M, while their lower limits of determinable concentrations–1.66×10−6 M and 1.07×10−6 M, respectively. The sensor is more sensitive to D‐tryptophan (ΔEp=20 mV, ipD/ipL=1.58). The developed sensor was shown to successfully determine tryptophan enantiomers in model solutions of pure enantiomers, in a mixture of enantiomers, in biological fluids, and in tablet forms of biologically active additives. It was shown that the suggested sensor made it possible to determine the ratio of L‐ and D‐enantiomers of tryptophan in a mixture with a high probability. [ABSTRACT FROM AUTHOR]

In this work, we study the structure and ratio of (R)‐4‐menthen‐3‐one conformers using ab initio methods. It was shown that the methyl group in (R)‐4‐menthen‐3‐one preferred an equatorial position. In the most stable conformer of the (R)‐4‐menthen‐3‐one, the methyl radical of the i‐Pr group is oriented to C=C double bond, so this group has a more steric hindrance effect on double bond. The ratio of conformers in solvents increases in favor of the most stable conformer. [ABSTRACT FROM AUTHOR]