HPLC Enantioseparation of Phenylcarbamic Acid Derivatives by Using Macrocyclic Chiral Stationary Phases

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

HPLC separation and determination of dicoumarol and other simple coumarins in sweet clover

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)

Involvement of Deep Eutectic Solvents in Extraction by Molecularly Imprinted Polymers—A Minireview

Substantial research activity has been focused on new modes of extraction and refining processes during the last decades. In this field, coverage of the recovery of bioactive compounds and the role of green solvents such as deep eutectic solvents (DESs) also gradually increases. A specific field of DESs involvement is represented by molecularly imprinted polymers (MIPs). The current state and prospects of implementing DESs in MIPs chemistry are, based on the accumulated experimental data so far, evaluated and discussed in this minireview

Separation Of Methionine Enantiomers By Using Teicoplanin And Cyclofructan Columns

Methionine is a naturally occurring amino acid. Its enantiomeric separation by using high performance liquid chromatography on various types of chiral stationary phases was studied. The effect of mobile phase composition on enantioselectivity and retention was considered. The separation of the enantiomers was attained in different separation modes – reversed phase mode for the macrocyclic antibiotic chiral stationary phases (teicoplanin, teicoplanin aglycone), normal phase and polar organic phase modes for the isopropyl carbamate cyclofructan 6 chiral stationary phase. It was shown that the hydrogen bonding, dipole interactions, steric effects between methionine molecules and stationary phases play an important role in the separation of enantiomers