Colourimetric Determination of High-Density Lipoprotein (HDL) Cholesterol Using Red–Green–Blue Digital Colour Imaging

ABSTRACT

A rapid, low-cost, and sensitive method was developed for the quantification of high-density lipoprotein cholesterol based on enzymatic colorimetric reactions and digital image analysis. The proposed method was adapted to a 96-microwell enzyme-linked immunosorbent assay plate and imaging acquisition was performed using a conventional desktop scanner. The images were recorded using the red–green–blue color system in which the resolved absorbance for each color channel was used for multiple linear regression. The regression model presented a root mean squared error of calibration and a correlation coefficient (R²) value of 1.53 mg dL⁻¹ and 0.995, respectively. Prediction was obtained with a root mean square error of prediction of 2.42 mg dL⁻¹ and R² of 0.993, thereby showing accurate prediction response. A limit of detection of 0.43 mg dL⁻¹ and precision better than 1.72% reinforced these results. This method was compared with a reference methodology using ultraviolet–visible spectroscopic measurements at 500 nm and no statistical differences were observed at the 95% confidence level, showing the potential for future clinical applications.

KEYWORDS:

• Colorimetry
• enzyme-linked immunosorbent assay (ELISA)
• high-density lipoprotein (HDL) cholesterol
• multiple linear regression
• red–green–blue (RGB) color system

Additional information

Funding

Camilo L. M. Morais would like to thank CAPES-Brazil (Doutorado Pleno no Exterior, grant 88881.128982/2016-01) for financial support. Kássio M. G. Lima thanks the CNPq grant (305962/2014-0) for financial support.