The Clean-Trace™ Surface Protein Allergen Test is based on the Biuret reaction. Under alkaline conditions the copper ions (Cu2+) form a complex with peptide bonds of protein and become reduced to Cu+. Bicinchoninic acid (BCA) under alkaline conditions is a highly sensitive, stable and specific reagent which forms a purple complex with Cu+. The test provides an estimation of protein by means of a color change. The  Clean-Trace Protein Allergen Test is a sensitive protein detection swab, with a detection limit of approximately 3 μg of total protein (using Bovine Serum Albumin as control). The absolute limit will vary with the protein composition of samples 2 tested. When testing surfaces, equipment and rinse solutions, it is important to note that a residue may contain a mixture of allergenic and non-allergenic proteins, as well as non-protein materials. To provide some guidance on the interpretation of results, testing at Neogen has shown that a positive  Clean-Trace Protein Allergen Test result could equate to the presence of the following approximate minimum amounts of allergenic products:

Allergen Detection Limit	Material Used	Protein Content (%)
Egg 10-20 μg	NIST SRM8415 Whole egg powder	30
Milk 10-20 μg	NIST SRM8435 Whole milk powder	25.9
Peanut 25-50 μg	NIST SRM2387 Peanut butter	22.2
Gluten 40 μg	Gluten flour (locally sourced)	~83
Soy 20-40 μg	Soy flour (locally sourced)	~46.5
Almond 20-40 μg	Whole almond (locally sourced)	~19.5
Buckwheat 20-40 μg	Buckwheat flour (locally sourced)	~13