Contribution to the quantitative and enantioselective determination of kavapyrones by high-performance liquid chromatography on ChiraSpher NT material

Separation and identification of cis and trans isomers of 2-butene-1,4-diol and lafutidine by HPLC and LC-MS

The cis and trans isomers separation of 2-butene-1,4-diol and lafutidine were studied by HPLC on two kinds of chiral columns: (S,S)-Whelk-O 1 and ChiraSpher. The isomers of 2-butene-1,4-diol can be separated on both chiral columns while the isomers of lafutidine can only be resolved on ChiraSpher column. The influence of different type and amount of mobile phase modifier on the isomers separation was extensively studied. The resolution of cis and trans isomers of 2-butene-1,4-diol was 2.61 on (S,S)-Whelk-O 1 column with hexane-ethanol (97:3, v/v) as the mobile phase. The resolution of lafutidine was 1.89 on ChiraSpher column with hexane-ethanol-THF-diethylamine (92:3:5:0.1, v/v/v/v) as the mobile phase. LC-MS methods were developed to identify the isomer peaks.

Analysis of plant extracts by NIRS: simultaneous determination of kavapyrones and water in dry extracts of Piper methysticum Forst

A near-infrared reflection spectroscopy (NIRS) method was developed to determine the total content of kavapyrones, kavain and water in dry extracts of Piper methysticum Forst. (kava kava, Piperaceae). Based on the recorded spectra and the reference data, performed by HPLC and Karl Fischer titration, a chemometrical analysis was calculated using PLS 2 algorithm. In general, good calibration statistics are obtained for the prediction of the different contents presenting high correlation coefficients (r(2) > 0.9913) and low root mean square errors of prediction (RMSEP < 0.094%). Usually the main water bands are "cut out" of the spectra to improve the model, however this is associated with the loss of relevant spectroscopic information. Thus, the entire spectrum including the OH bands is used, as these are not only found in water but also in the kavapyrones. The use of this new strategy succeeds in overcoming the difficulties in NIRS and establishes NIRS as a valid alternative in the routine quality control of plant extracts.

Computer-assisted optimization in the development of a high-performance liquid chromatographic method for the analysis of kava pyrones in Piper methysticum preparations

A computer simulation program was used to optimize the separation for six kava pyrones and two unidentified components obtaining the best resolution and the shortest run time. With DryLab it was possible to find the best separation conditions without running a large number of possible combination of variables in the laboratory. Additionally, due to the systematic progress in method development a new eluent was found with excellent properties, namely 2-propanol. With 2-propanol, the largest number of components could be revealed in the shortest analysis time. Starting with four initial experiments, the software allowed to optimize gradient time tG and temperature T simultaneously. Changing other variables such as type of organic modifier, the eluent pH, the gradient form, and the flow-rate, the optimization resulted in resolution Rs > 1.5 for all kava pyrones and the two additional new bands. The HPLC method is used to analyze kava pyrones in Piper methysticum preparations.