Determination of Cinchona Alkaloids by Capillary Electrophoresis with Novel Complex Formation

Polysaccharide-based chiral stationary phases as efficient tools for diastereo- and enantioseparation of natural and synthetic Cinchona alkaloid analogs

In this study, we present results obtained on the diastereo- and enantioseparation of some basic natural and synthetic Cinchona alkaloid analogs by applying liquid chromatographic (LC) and subcritical fluid chromatographic (SFC) modalities on amylose and cellulose tris-(phenylcarbamate)-based stationary phases using n-hexane/alcohol/DEA or CO₂/alcohol/DEA mobile phase systems. Seven chiral stationary phases in their immobilized form were employed to explore their stereoselectivity for a series of closely related group of analytes. The most important characteristics of LC and SFC systems were evaluated through the variation of the applied chromatographic conditions (e.g., the nature and content of the alcohol modifier, the concentration of additives, temperature). The columns Chiralpak IC and IG turned out to be the best in both LC and SFC modalities. Temperature-dependence study indicated enthalpy-controlled separation in most cases; however, separation controlled by entropy was also registered.

New, inexpensive and simple 3D printable device for nephelometric and fluorimetric determination based on smartphone sensing

A new, inexpensive and easy to use 3D printable device was developed for nephelometric and fluorimetric determination. Its applicability was tested for the quantification of quinine in tonic drinks and sulfate in natural water with good analytical accuracy. In this way, sulfate determination was carried out by nephelometry using a red LED, while quinine was determined using a blue LED by fluorimetry. A smartphone camera was used to take the pictures and afterwards transform them into the RGB color space using the software ImageJ by a personal computer. The linear range was 2.0–50.0 mg L⁻¹ for sulfate with a LOD of 0.13 mg L⁻¹, and the corresponding quantification limit (LOQ) was 0.43 mg L⁻¹. The linear range for quinine was from 0.42 to 3.10 mg L⁻¹. The LOD and LOQ were 0.11 mg L⁻¹ and 0.38 mg L⁻¹, respectively.

A new, inexpensive and easy to use 3D printable device was developed for nephelometric and fluorimetric determination.

Quantitative determination of major alkaloids in Cinchona bark by Supercritical Fluid Chromatography

Chinoline alkaloids found in Cinchona bark still play an important role in medicine, for example as antimalarial and antiarrhythmic drugs. For the first time Supercritical Fluid Chromatography has been utilized for their separation. Six respective derivatives (dihydroquinidine, dihydroquinine, quinidine, quinine, cinchonine and cinchonidine) could be resolved in less than 7 min, and three of them quantified in crude plant extracts. The optimum stationary phase showed to be an Acquity UPC² Torus DEA 1.7 μm column, the mobile phase comprised of CO₂, acetonitrile, methanol and diethylamine. Method validation confirmed that the procedure is selective, accurate (recovery rates from 97.2% to 103.7%), precise (intra-day ≤2.2%, inter-day ≤3.0%) and linear (R² ≥ 0.999); at 275 nm the observed detection limits were always below 2.5 μg/ml. In all of the samples analyzed cinchonine dominated (1.87%-2.30%), followed by quinine and cinchonidine. Their total content ranged from 4.75% to 5.20%. These values are in good agreement with published data, so that due to unmatched speed and environmental friendly character SFC is definitely an excellent alternative for the analysis of these important natural products.

An Optimised Method for Routine Separation and Quantification of Major Alkaloids in Cortex Cinchona by HPLC Coupled with UV and Fluorescence Detection

INTRODUCTION

Authentication of herbal products to ensure efficacy and safety require efficient separation and quantification of constituents. Standard assays for Cinchona bark used for the treatment of malaria and production of quinine, either use only spectrophotometry to detect two pairs of diastereoisomers of quinine and cinchonine type alkaloids (European Pharmacopoeia, Ph.Eur.) or liquid chromatography primarily optimised for detection of the four major alkaloids. However, numerous minor alkaloids occur in Cinchona and related species and efficient separation including gradient elution is necessary in order to obtain the full pattern of constituents in bark samples.

OBJECTIVE

To develop an optimised HPLC method for separation and quantitative analysis of the four major alkaloids in Cinchona bark using UV detection.

METHODOLOGY

Dimethyl sulphoxide (DMSO) extracts of 50 mg of pulverised barks were prepared using ultrasonication. The chromatographic separation was performed on an XB-C18 column packed with 2.6 μm particles. Gradient elution using an ammonium formate buffer and methanol as organic modifier over 26 min was based on non-chiral separation of the diastereoisomers and the high solvent selectivity of methanol. Post column UV detection was performed at 250 nm and 330 nm. Fluorescence detection was performed using 330 nm for excitation and 420 nm for emission.

RESULTS

The optimised HPLC method facilitates efficient separation and quantification of the four major alkaloids in 26 min with a limit of quantification of 5 μg/g from 50 mg bark sample.

CONCLUSION

The optimised HPLC method offers a simple and efficient quantification of the four major alkaloids. Copyright © 2017 John Wiley & Sons, Ltd.