Analytical Methods for Melatonin Quantification: Advances, Challenges, and Clinical Applications

Area of Science:

• Biochemistry and Analytical Chemistry
• Chronobiology and Sleep Medicine

Background:

• Melatonin, an indoleamine, regulates critical physiological processes like circadian rhythms and sleep-wake cycles.
• Its presence in biological fluids at picogram or femtogram levels presents significant analytical quantification challenges.
• Accurate melatonin measurement is essential for clinical diagnostics, pharmacological research, and understanding circadian rhythm disorders.

Purpose of the Study:

• To critically assess and compare current analytical methodologies for melatonin determination in diverse biological matrices.
• To evaluate the strengths and limitations of various techniques, including immunoassays, spectrophotometry, chromatography-mass spectrometry, and biosensors.
• To guide researchers and clinicians in selecting optimal analytical approaches for melatonin quantification.

Main Methods:

• Narrative review synthesizing data from published literature on melatonin quantification techniques.
• Comparative analysis of methods based on sensitivity, specificity, reproducibility, cost, and clinical applicability.
• Discussion of established techniques (immunoassays, LC-MS/MS) and emerging technologies (biosensors, microextraction).

Main Results:

• Immunoassays and colorimetric methods offer cost-effective, accessible options for preliminary or large-scale studies.
• Liquid chromatography-tandem mass spectrometry (LC-MS/MS) provides high sensitivity (sub-picogram limits) and specificity, serving as a benchmark for reference analysis.
• Emerging biosensors and sample preparation techniques (e.g., dispersive microextraction) show potential for developing portable, sustainable, and sensitive analytical platforms.

Conclusions:

• No single method is universally optimal; the choice depends on specific application requirements (e.g., cost, throughput, required sensitivity).
• LC-MS/MS remains the gold standard for precise melatonin quantification but faces challenges in cost and accessibility.
• Advancements in biosensor technology and sample preparation herald a new era of more accessible and potentially point-of-care melatonin analysis.