New UHPLC – method to determine Aloin A and B in Aloe capensis

Introduction: The current monograph in the European Pharmacopeia for Aloe capensis describes a photometric assay based on an adapted bornträger reaction to determine hydroxyanthracene glycosides, calculated as aloin A. The method is time consuming, unspecific for aloin A and B and the precision is not adequate for a modern assay. There are several HPLC methods published, but their runtime is too long and the resolution for aloin A and B is not satisfactory. There is no validated and robustness checked method at all.

Aim: The aim of the present study was to develop a short, robust and validated UHPLC method that meets specific needs of the pharmaceutical industry, this means short retention times and high repeatability. The method is suitable for the analysis of herbal drug and herbal drug preparation.

Method: About 100 mg of the drug are placed in a 100 mL volumetric flask and extracted with 70 mL of methanol for 20 min with ultrasound. An Acquity UHPLC BEH Phenyl Column (2.1 × 50)mm, 1.7 µm was used as stationary phase. The mobile phase consists of 17% acetonitril, and 83% water. The flow rate is 0.5 mL/min, the detection wavelength 355nm, and the injection volume 3µL. The method was validated according to ICH guidelines.

Results: The mobile phase separates aloin A and B. Results of several samples will be presented on the poster. A chromatogram from a Aloe capensis sample is shown in figure 1.

Fig. 1: Chromatogram of a Aloe capensis sample

Conclusion: The method we developed is simple, robust and precise. The method is also available for normal HPLC systems. It is a suitable option to replace the outdated photometric assay described in the European Pharmacopeia.

Keywords: UHPLC, Aloe capensis, aloin A, aloin B