Plasma catecholamines via an improved fluorimetric assay: comparison with an enzymatic method

Area of Science:

• Biochemistry
• Analytical Chemistry
• Clinical Chemistry

Background:

• Accurate measurement of plasma catecholamines like norepinephrine (NE) and epinephrine (E) is crucial for diagnosing and managing conditions such as hypertension.
• Existing enzymatic methods for catecholamine quantification can be time-consuming and expensive.
• Development of a more efficient and reliable assay is needed.

Purpose of the Study:

• To modify and validate a fluorimetric method for the simultaneous determination of plasma NE and E.
• To compare the modified fluorimetric method with a standard enzymatic method.
• To assess the economic viability and time efficiency of the new assay.

Main Methods:

• The Renzini and Valori fluorimetric method was adapted using alumina and ion exchange chromatography.
• dl-3H norepinephrine (3H-NE) was incorporated for individual plasma NE recovery assessment.
• Mercaptoethanol was used as a stabilizing agent for fluorescent lutines.

Main Results:

• High correlations were observed between the fluorimetric and enzymatic methods for NE (r = 0.98) and total plasma catecholamines (r = 0.98).
• A significant correlation was also found for E concentrations (r = 0.79).
• The method demonstrated excellent reproducibility with a standard deviation below 10% for 10 ml plasma aliquots.

Conclusions:

• The modified fluorimetric method provides a reliable, economical, and less time-consuming alternative for quantifying plasma NE and E.
• This assay is suitable for clinical settings, particularly for hypertensive patients.
• The enhanced method offers comparable accuracy to established enzymatic techniques.