Colorimetry

The evaluation of cosmetic products has evolved significantly in recent years, driven by the growing demand for safe, effective, and consumer-friendly formulations. Traditional sensory analysis, which relies on human perception of attributes such as texture, fragrance, spreadability, and overall acceptability, continues to play a crucial role in understanding consumer preferences. However, the limitations of subjectivity and variability have encouraged the integration of advanced instrumental techniques. Modern instrumental methods—including rheology, texture analysis, colorimetry, spectroscopy, chromatography, and imaging technologies—provide objective, quantifiable, and reproducible data that complement sensory evaluations. Together, these approaches enable a more comprehensive assessment of cosmetic performance, stability, and consumer satisfaction. This synergistic use of sensory and instrumental methods not only enhances product development and quality control but also supports regulatory compliance and innovation in the cosmetics industry. The paper highlights recent advances, methodological improvements, and the importance of combining instrumental precision with sensory insights for holistic cosmetic evaluation.

Aloe gel is commonly used in herbal medicines. Many of the Aloe products available commercially, do not demonstrate beneficial effects, indicating the poor quality of the Aloe gel. Therefore, an efficient, reliable and accurate method is needed to evaluate the quality of Aloe products. The present research work discussed the development of a colorimetric and HPTLC method for the determination of Glucomannan (a marker compound for Aloe gel) in Aloe gels and its preparations. Shimadzu 1700 UV-Visible spectrophotometer was used for the colorimetric estimation. In the colorimetric method developed obeyed the Beer’s law in the concentration range of 50-90 μg-ml-1 with r2 of 0.999. CAMAG HPTLC instrument was used. The mobile phase comprised of n-butanol : ethanol : water : acetic acid (2 : 4 : 4 : 0.05 v/v) was used for the development of chromatogram. The densitometric scanning was done by TLC scanner III (CAMAG) in absorbance mode at the wavelength of 488 nm. After spraying with anisaldehyde sulfuric acid the system was found to give compact spots for glucomannan (Rf value of 0.69±0.02). The data obtained showed good linearity (r2 = 0.995) with respect to peak area in the concentration range of 400-1400 ng spot-1.