Determination of Aloin A and Aloin B in Aloe vera Raw Materials and Finished Products by High-Performance Liquid Chromatography: Single-Laboratory Validation.

A single-laboratory validation (SLV) was conducted on an HPLC method for the detection and quantification of aloin A and aloin B in Aloe vera raw materials and finished products. An extraction procedure using sonication with an acidified solvent was used for solid test materials while liquid test materials only required dilution, if necessary, prior to filtration and analysis. Separation was achieved using a fused core C18 column in 18 min under isocratic elution conditions allowing for a single analyte (aloin A) calibration curve to quantify both aloins. Adequate chromatographic resolution (Rs ≥ 1) was achieved for aloin A and aloin B. The calibration curves for aloin A exhibited coefficients of determination (r(2)) of ≥ 99.9% over the linear range of 0.3-50 μg/mL. The LOD values were 0.092 and 0.087 μg/mL, and LOQ 0.23 and 0.21 μg/mL for aloin A and aloin B, respectively. Repeatability studies were performed on nine test materials on each of 3 separate days, with five of the test materials determined to be above the LOQ having repeatability RSD (RSDr) values ranging from 0.61 to 6.30%. Method accuracy was determined through a spike recovery study on both liquid and solid matrixes at three different levels: low, medium, and high. For both aloins, the recovery in the liquid matrix ranged from 92.7 to 106.3% with an RSDr of 0.15 to 4.30%, while for the solid matrix, the recovery ranged from 84.4 to 108.9% with an RSDr of 0.23 to 3.84%. Based on the results of the SLV study, it is recommended that this method be evaluated for reproducibility through a collaborative study.