Alizarin (anthraquinone/hydroxyanthracene) assay

Alizarin is a natural pigment belonging to the anthraquinone family, also classified as a hydroxyanthracene. Historically, it has been extracted from the root of madder ( Rubia tinctorum ), a plant widely used since antiquity for dyeing textiles. Today, alizarin is experiencing renewed interest in the plant and nutraceutical sectors, both for its potential antioxidant properties, its role as a phytochemical marker, and its use as a tracer of authenticity in traditional plant extracts. The precise measurement of alizarin is therefore an important analytical challenge for characterizing, standardizing, and controlling the quality of plant-based products.

Analytical and industrial interest of the dosage

Alizarin analysis serves several industrial and scientific purposes. In the field of plant extracts, it allows for the validation of the botanical identity and authenticity of madder extracts or traditional formulations based on dye plants. Since alizarin is a characteristic compound of Rubia tinctorum , its quantification helps differentiate natural extracts from adulterated or substituted products.
In nutraceuticals, the analysis is used to standardize extracts , guarantee a controlled content of anthraquinone compounds, and ensure consistent quality between batches. It can also be used in R&D studies aimed at exploring the biological properties of alizarin, particularly its antioxidant potential or metabolic behavior. Finally, in a regulatory and quality context, this analysis allows for monitoring the presence of compounds from the hydroxyanthracene family, some of which are subject to specific requirements depending on their intended use.

Principles and operation of analytical methods

Alizarin quantification relies primarily on high-precision chromatographic techniques. High-performance liquid chromatography (HPLC) , often coupled with diode array detection (HPLC-DAD), allows alizarin to be separated from other compounds present in the matrix and identified by its characteristic UV-visible absorption spectrum. This approach is widely used for colored plant extracts and complex matrices.
Liquid chromatography-mass spectrometry (LC-MS) provides an additional level of specificity and sensitivity. It is particularly relevant when alizarin is present at low concentrations or when the matrix contains several structurally similar anthraquinones. Mass spectrometry enables unambiguous identification and reliable quantification, even in complex formulations.
In some cases, colorimetric methods can be used for exploratory or comparative purposes, but HPLC and LC-MS remain the reference methods for usable results in quality control and R&D.

Applications in the nutraceutical and plant sectors

In the plant sector, alizarin analysis is used to characterize madder extracts, plant powders, and traditional tinctures. It allows for the evaluation of pigment richness, the comparison of different botanical origins or extraction processes, and the monitoring of the compound's stability during storage.
In nutraceuticals, this analysis contributes to the qualification of plant ingredients used in food supplements or functional formulations. It is part of a process of controlling active compounds and ensuring the safety of formulations, particularly when anthraquinones are involved. Alizarin can also serve as an analytical marker in studies of the authenticity or traceability of plant raw materials.

Analyzed matrices

Alizarin can be measured in a wide range of matrices: liquid or dry madder extracts, plant powders, natural tinctures, dietary supplements (capsules, tablets, powders), functional ingredients, and traditional preparations based on coloring plants. Analytical protocols are adapted to the nature of the matrix to ensure efficient extraction and reliable quantification.

Quality of results and interpretation

Analyses are performed using reference standards that allow for the precise quantification of alizarin (CAS 72-48-0). Results can be expressed as mass content or as a percentage of dry matter, as required. They are suitable for quality control, standardization, product development, and technical documentation. Interpretation of the results takes into account the natural variability of the plants, extraction processes, and storage conditions.

Added value YesWeLab

YesWeLab relies on a network of expert laboratories specializing in plant compound analysis, equipped with high-performance HPLC and LC-MS equipment. The majority of our partners are ISO 17025 and COFRAC certified or accredited, guaranteeing the reliability, traceability, and compliance of analyses. Our scientific team assists you in selecting the analytical method best suited to your matrix and your objective (authenticity, standardization, R&D, quality control). Since 2020, manufacturers, distributors, and engineering firms have entrusted us with the management of their analyses via our digital platform, ensuring centralized, rigorous, and responsive monitoring.

Related analyses in the YesWeLab catalog

To complement the alizarin assay, the following tests are frequently performed:

• Total polyphenol content
• Studies of authenticity and traceability of plant extracts
• Stability analyses of natural pigments