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Dicoumarol is a mycotoxin, that acts as a blood anticoagulant, is formed during the microbial action of molds and fungi in spoiled hay or silage containing high-coumarin plant. A HPLC-DAD method for determination of coumarins, including dicoumarol, coumarin, and 4-hydroxycoumarin was developed. Methanol and acetic acid were used as mobile phase with gradient elution. The simultaneous separation was performed using C18 type of stationary phase. The recoveries were 88.6 – 92.6 %, 91.8 – 95.0 %, and 89.7 – 94.1 % (evaluated for three concentration levels) for dicoumarol, coumarin, and 4-hydroxycoumarin respectively. The parameters of system suitability (repeatability of retention times and peak areas) were determined for evaluation of the method. The method showed a good linearity in the concentration range 0.7 – 100 μg.mL−1 for dicoumarol, 0.05 – 100 μg.mL−1 for coumarin and 4-hydroxycoumarin with correlation coefficients higher than 0.9885. Extracts of sweet clover herb, hay, and spoiled hay were subjected to HPLC-DAD analysis. The most abundant compound in sweet clover herb and hay extracts was coumarin. In spoiled sweet clover hay extract the 4-hydroxycoumarin was detected in addition. The formation of 4-hydroxycoumarin was also observed in the synchronous fluorescence spectra recorded at the wavelength difference of 90 nm (difference between emission and excitation wavelength).

Two molecularly imprinted polymers for 1-methyl-2-piperidinoethyl ester of 4-decyloxyphenylcarbamic acid (template) have been synthesized using a non-covalent imprinting approach. Acrylamid and methacrylic acid, respectively, were used as the functional monomers. Imprinted polymers were used as the sorbents for solid phase extraction (MISPE). The capacity and selectivity of prepared imprinted polymers was investigated. The non-imprinted (blank) polymers were prepared by the same way, without the template, to study the non-specific interactions. Molecularly imprinted polymers were used to extract derivatives of alkoxyphenylcarbamic acid from spiked human plasma. C18 sorbent was also used for SPE to compare the efficiency of the procedure. [ABSTRACT FROM AUTHOR]

It has been found that the teicoplanin aglycone (CHIROBIOTIC TAG) chiral stationary phase is a useful column for the high performance liquid chromatographic (HPLC) separation of enantiomers of 1-methyl-2-piperidinoethylesters of 2-, 3- and 4-alkoxy-phenylcarbamic acid (potential local anaesthetic drugs) in the polar organic mode. The enantiomers were separated on a CHIROBIOTIC TAG column, isothermally in the range of 0–50°C with 10°C increments, using methanol [100 mL (v)] containing 17.5 mmol L−1 acetic acid and 4.8 mmol L−1 diethylamine as a mobile phase. van't Hoff plots (dependence of ln ki on 1/T, where k is the retention factor of a solute i and T is the temperature) were linear in the studied temperature interval. This allowed the determination of interaction enthalpies (ΔHi), entropy (ΔSi), and Gibbs energies (ΔGi). This thermodynamic information was used to evaluate the retention and resolution of enantiomers of studied analytes in this HPLC system. [ABSTRACT FROM AUTHOR]

The melting temperature of nine piperidinoethyl esters of alkoxyphenylcarbamic acid (hexaoxy-octyloxy) including all site isomers was investigated. The analyses were performed using DSC apparatus, sample mass ranged from 0.2 to 2.5 mg, heating rate was 5 K min-1 and in static air atmosphere. On the basis of melting peak, thermodynamic figures like: enthalpy, entropy, height and area of the peak and temperature of the partial peak were fixed. For evaluation of the results Principal Component Analysis was applied. Thanks to this method the influence of length (mass) and position of alkoxy substituents on the thermodynamic parameters of melting of compounds under investigation were determined. [ABSTRACT FROM AUTHOR]

The HPLC by using chiral stationary phases based on macrocyclic antibiotics, dimethylphenyl carbamate cyklofructan 7 and β-cyclodextrin in terms of polar-organic separation mode (mobile phase methanol/acetonitrile/acetic acid/triethylamine) were used for enantioseparation of alkoxy derivatives of phenylcarbamic acid. The effect of the analyte structures on the efficiency of enantioseparation was investigated. The most suitable stationary phase was teicoplanin aglycone, where the separations of the enantiomers were obtained (the resolution value from 0.65 to 2.90, depending on the structure of the analyte). Significant effect on the resolution of the enantiomers has position of alkoxy substituent in the hydrophobic part of the molecule. The enantiorecognition was achieved for 3-alkoxysubstituted derivatives.