Tryptophan assay

Tryptophan testing allows for the quantification of this essential amino acid , a major precursor to serotonin and melatonin , which is involved in the regulation of mood, sleep, and energy metabolism.
Indispensable for protein synthesis and the production of niacin (vitamin B3), tryptophan is a key indicator of the nutritional value of foods and nutraceutical formulations .

The analysis is carried out by high-performance liquid chromatography (HPLC) or mass spectrometry (LC-MS/MS) , after acid or enzymatic hydrolysis of the samples to release the free amino acid.

Analytical methods and protocols

The assay is based on the chromatographic separation of amino acids after extraction and possible derivatization.

• In HPLC-DAD or HPLC-fluorescence , the detection of tryptophan is carried out at a specific wavelength (280 nm).
• In LC-MS/MS , the method offers excellent sensitivity and selective identification even in complex matrices.

The parameters measured include:

• The free or total tryptophan content (mg/g or %),
• The amino acid profile of a sample,
• The stability and bioavailability of the compound in a given formulation.

The methods can follow the ISO 13903 , AOAC 988.15 , or Commission Directive 98/64/EC for food and nutritional matrices.

Industrial and scientific applications

Tryptophan testing is widely used in the following sectors:

• Human and infant nutrition : formulation of products enriched with essential amino acids.
• Animal nutrition : control of the tryptophan/lysine/methionine ratio in compound feeds.
• Nutraceuticals : standardization of supplements promoting sleep, relaxation or emotional regulation.
• Research in plant biology : study of plant indole metabolism and the biosynthesis of growth hormones (auxins).

This analysis guarantees the nutritional quality and traceability of the formulations , while supporting the functional and regulatory claims.

Matrices involved

• Food products (plant-based proteins, milk, flours, legumes),
• Animal feed and nutritional premixes,
• Dietary supplements (powders, capsules, plant extracts),
• Fermented products or products enriched with amino acids,
• Plant extracts rich in tryptophan derivatives.

Further analyses recommended

For a complete understanding of tryptophan metabolism and its bioactive derivatives, YesWeLab recommends combining this dosage with:

• Serotonin measurement , to monitor metabolic conversion towards the serotonergic pathway,
• Dosage of tryptophol , an indolic metabolite derived from tryptophan,
• Tryptamine assay , a derivative molecule involved in neurotransmission,
• Melatonin dosage , the final hormone in the tryptophan pathway,

YesWeLab's expertise

YesWeLab relies on a network of ISO 17025 and COFRAC accredited laboratories specializing in the chromatographic analysis of amino acids and indole metabolites .
Our teams support manufacturers and formulators in the standardization of nutritional products , biochemical characterization , and regulatory compliance .

Thanks to the YesWeLab digital platform , you can:

• Order your analyses online,
• Track your samples and results in real time
• Compare your batches to ensure the stability and quality of your formulas.