Straightforward and affordable electrochemical sensing for collagen quality assessment in supplements: A novel strategy for hydroxyproline quantification

Hydroxyproline (Hyp) is one of the most significant biomarkers of collagen content. It is useful not only for clinical tracking but also for proving the quality of collagen-based dietary supplements. Due to the increasing popularity of collagen supplement consumption, this work presents a novel approach for the determination of collagen content using the hydroxyproline method. This study is the first report that describes the use of an unmodified screen-printed carbon electrode as an efficient and streamlined sensor for the detection of Hyp. The highlight of this research is eliminating any need for complicated preparation and detection processes. The measurement relies on the indirect detection of Hyp by comparing the signal of Cu(II) ions in the absence and presence of Hyp, using a sequential drop mixture of the sample and Cu(II) in a basic condition. Key parameters related to square wave anodic stripping voltammetry (SWASV) for detection were systematically examined to improve sensitivity and accuracy. Under optimal conditions, the modification-free sensor offers good performance for Hyp detection with a linear range of 0.5–10 mM and a detection limit of 0.15 mM. In practical analysis, Hyp in the collagen supplement samples was detected with an acceptable recovery range of 80.36–107.89 % (n = 3). In addition, the results obtained from the suggested approach were validated against the conventional standard technique. A paired t-test at the confidence level of 95 % shows no significant difference between the two methods. Therefore, this proposed method offers a promising assay for routine and real-time collagen analysis in food quality and safety control.