Simple Determination of p-Cresol in Plasma Samples Using Fluorescence Spectroscopy Technique

Area of Science:

• Analytical Chemistry
• Clinical Chemistry
• Biomarker Detection

Background:

• Clinical investigations require simple, fast, and reliable methods for biological indicator analysis.
• p-Cresol (pC) and its conjugates (pCS, pCG) are potential biomarkers, but their quantification in plasma is challenging.
• Existing methods may lack the speed, cost-effectiveness, or specificity needed for routine clinical use.

Purpose of the Study:

• To develop and validate a novel, cost-effective, and specific method for p-cresol extraction and quantification in human plasma.
• To assess the method's reliability, including repeatability, selectivity, and accuracy.
• To investigate the method's applicability for p-cresol detection in chronic kidney disease (CKD) patients.

Main Methods:

• Plasma samples were acid-hydrolyzed to convert p-cresol sulfate (pCS) and p-cresol glucuronide (pCG) to free p-cresol (pC).
• Protein precipitation followed by acetonitrile extraction with saturated NaCl (salting-out) was used for pC isolation.
• Quantification was performed using fluorescence spectroscopy with excitation/emission wavelengths of 280/310 nm.

Main Results:

• The developed method demonstrated high specificity for p-cresol, with minimal interference from other substances.
• A linear detection range of 0.5 to 30 µg/mL was established, with a low limit of detection (LLOQ) of 0.5 µg/mL.
• The method exhibited excellent reliability, confirmed by high repeatability, selectivity, and accuracy in plasma samples.

Conclusions:

• This novel method provides a simple, fast, cheap, and specific means for quantifying p-cresol in CKD patient plasma.
• The developed assay is suitable for routine analysis of p-cresol concentrations in clinical settings.
• The method holds significant potential for adaptation into a point-of-care testing (POCT) device for CKD management.