Eco-Friendly Spectrophotometric and Paper-Based Microfluidic Techniques for Creatinine Determination in Serum

Abstract

Creatinine is a key marker for renal function, and accurate measurement of creatinine in serum is important for clinical diagnostics. In the present work, a new colorimetric method using the creatinine-chlorophenol red (CPR) reaction was introduced and conducted with ultraviolet-visible and paper-based microfluidic (µPAD) measurement. Optimal conditions were established for each method, whereas analytical performance in terms of linearity, sensitivity, precision, recovery, and comparison with the reference analyzer (Cobas c311) was evaluated. A spectrophotometric method based on the formation of a pink-violet ion-pair complex and its bathochromic shift with an absorption maximum at 576 nm was developed, linear over 2–130 µg/mL, the limit of detection (LOD) was 1.2 µg/mL, and the limit of quantification (LOQ) was 2.25 µg/mL. Finally, the µPAD-based assay was optimized using a higher CPR concentration (100 µg/mL) and had a linear range of 10–160 µg/mL (R² = 0.9972), and LOD and LOQ were 7.0 and 11.57 µg/mL, respectively. Recovery values between 97.1 and 104.3%, corresponding closely to values obtained using a Cobas c311 analyzer, were achieved. The two procedures followed the tenets of Green Analytical Chemistry. These results underscore the robustness, sensitivity, and long-term stability of these approaches, thereby indicating their potential suitability for both laboratory-based centralized detection and point-of-care decentralized diagnostics.