Colorimetric Analysis of Metabolites in Biological Fluids

Colourimetric analysis of metabolites in biological fluids encompasses a suite of techniques in which specific chemical reactions produce a measurable change in colour proportional to the concentration of target analytes. Common sample matrices include blood, urine, saliva and sweat, each presenting distinct challenges in terms of matrix effects and required sensitivity. Chromogenic reagents such as picrate, nitrobenzenes or enzymatically generated dyes react with analytes—creatinine, urea, glucose, lactate and others—to yield coloured complexes. Quantification is typically achieved by measuring absorbance at characteristic wavelengths using spectrophotometers, portable photometers or smartphone-based detectors. Recent advances have focused on miniaturisation, integration with microfluidics and the use of engineered nanoparticles to enhance sensitivity and selectivity. Applications span clinical diagnostics, point-of-care testing, environmental monitoring and nutritional studies, with an emphasis on affordability and ease of use in resource-limited settings.

Research from Nature Portfolio

Recent studies have demonstrated the integration of microfluidic paper-based analytical devices with smartphone imaging to achieve real-time quantification of glucose and lactate in sweat samples. By patterning hydrophobic barriers on cellulose substrates and immobilising enzyme–substrate conjugates, these devices provide rapid, semi-quantitative readouts with minimal sample volume. Another advance employs plasmonic gold nanostructures functionalised with selective ligands for urea and uric acid detection. The localised surface plasmon resonance shift induced by analyte binding enhances colour contrast, enabling detection limits down to micromolar concentrations. A further innovation combines droplet-based microfluidics and enzymatic amplification to measure low-abundance metabolites in minute volumes of serum, offering high throughput and consistent reproducibility.

Colorimetric Analysis of Metabolites in Biological Fluids publication trend

The graph below shows the total number of articles in colorimetric analysis of metabolites in biological fluids across all publications each year (not limited to Nature Index journals).

Technical terms

Colourimetric assay: Analytical technique where analyte concentration is determined from the intensity of a colour produced by a chemical reaction.

Chromogenic substrate: A reagent that undergoes a colour change when reacting with a specific enzyme or analyte.

Microfluidic paper-based analytical device (µPAD): A paper platform patterned to control fluid flow for miniaturised assays.

Jaffé reaction: A chemical reaction between creatinine and picric acid in alkaline medium yielding a red-orange complex.

Localized surface plasmon resonance (LSPR): Optical phenomenon in metallic nanoparticles where incident light causes collective electron oscillations, sensitive to surface binding events.

References

1. Fast colorimetric detection of albumin-to-creatinine ratio using paper-based analytical devices with alkaline picrate and Bromothymol Blue reagents. Journal of Applied Pharmaceutical Science (2022).
2. A MICROCOLORIMETRIC DETERMINATION OF CREATINE IN URINE BY THE JAFFE REACTION. Journal of Biological Chemistry (1954).
3. DETERMINATION OF 3-HYDROXY-3-PYRROLINE-2-ONE IN URINE AND STUDY OF ITS EXCRETION FROM THE ORGANISM OF LABORATORY ANIMALS. Pharmacy & Pharmacology (2017).