Highly Sensitive and Selective Detection of L-Tryptophan by ECL Using Boron-Doped Diamond Electrodes

Area of Science:

• Analytical Chemistry
• Electrochemistry
• Biochemistry

Background:

• L-tryptophan is an essential amino acid crucial for human metabolism.
• Accurate detection of L-tryptophan is vital for medical diagnostics and food analysis.
• Existing detection methods may lack sensitivity or selectivity for complex biological matrices.

Purpose of the Study:

• To develop a novel electrochemiluminescence (ECL) method for sensitive and selective L-tryptophan detection.
• To investigate the role of in situ generated hydrogen peroxide in the ECL mechanism.
• To validate the method's performance in relevant biological and food matrices.

Main Methods:

• Utilized boron-doped diamond (BDD) electrodes for in situ hydrogen peroxide (H₂O₂) production.
• Employed electrochemiluminescence (ECL) detection coupled with H₂O₂ generation.
• Optimized reaction conditions including pH and concentration ranges.
• Assessed selectivity against potential interfering indolic compounds.

Main Results:

• Established a direct correlation between ECL response and H₂O₂ production at the BDD electrode surface.
• Demonstrated a linear relationship between ECL signal and L-tryptophan concentration from 0.005 to 1 µM.
• Achieved a low limit of detection (LOD) of 0.4 nM and limit of quantification (LOQ) of 1.4 nM in PBS.
• Exhibited excellent selectivity against structurally similar indolic compounds.

Conclusions:

• The developed ECL method provides a highly sensitive and selective approach for L-tryptophan quantification.
• In situ H₂O₂ generation on BDD electrodes is key to the ECL emission mechanism.
• This method shows significant potential for practical applications in clinical and food analysis.