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

Hroboňová, Katarína, Sádecká, Jana, Čižmárik, Jozef
Nova biotechnologica et chimica 2018 v.17 no.1 pp. 95-102
4-hydroxycoumarin, acetic acid, anticoagulants, blood, coumarin, dicoumarol, fluorescence emission spectroscopy, fungi, hay, high performance liquid chromatography, methanol, mycotoxins, silage, wavelengths
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).