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

Abstract

A rapid, low-cost and sensitive method for quantification of high-density lipoprotein (HDL) cholesterol based on enzymatic colorimetric reactions and digital image analysis was developed. The proposed method was adapted to a 96-microwell enzyme-linked immunosorbent assay (ELISA) plate and imaging acquisition was performed using a conventional desktop scanner. The images were recorded using the red-green-blue (RGB) colour system in which the resolved absorbance for each colour channel was used for multiple linear regression. The regression model presented a root mean squared error of calibration and 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; therefore, showing a good 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 UV-Vis measurements at 500 nm and no statistical difference was observed at a confidence level of 95%; showing its potential for future clinical applications.