Dot-blot assay with AlCl3 reagent for rapid screening of total flavonoid content in food and herbal medicine materials

Abstract The determination of total flavonoid content (TFC) through the aluminum chloride (AlCl 3 ) colorimetric test utilizing spectrophotometry is commonly used as a parameter for evaluating the quality of processes as well as food and herbal medicines materials. Nonetheless, it is laborious, lengthy, and necessitates substantial amounts of chemicals. This study aims to develop and validate the dot-blot assay with AlCl 3 reagent for determining TFC in plant materials. In this method, the samples were not subjected to chromatography; instead, the plates were derivatized using AlCl 3 in ethanol immediately after the application of samples and evaporation the solvent. The Al(III)-flavonoid complex was scanned (421 nm) using a TLC-scanner. The validation of the method was conducted on stability, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, and robustness. The TFC of samples determined by dot-blot assay and spectrophotometry was subsequently analyzed using linear regression and Pearson correlation. The dot-blot assay for determining TFC met the stability parameter (RSD = 1.31–8.25%), intraday precision (RSD = 2.20–6.11%), inter day precision (RSD = 1.56%), linearity ( r 2 = 0.9928), LOD (251.03 ng/spot), LOQ (760.71 ng/spot), accuracy (recovery = 70.81–75.61%), and robustness (RSD = 2.55 and 7.60%). There was a very strong positive linear relationship between the dot-blot assay method and spectrophotometry, with a linear regression coefficient of 0.9078 and a Pearson correlation coefficient of 0.911. The proposed method proved to be simpler, faster, and more economical for determining TFC. Thus, the method was beneficial in providing references for enhancing the quality control of food and herbal medicines.