Toluidine Blue O C.I. 52040


Toluidine Blue, also known as TBO or Tolonium Chloride (INN) is a blue cationic (basic) dye used in histology and sometimes clinically.

Toluidine blue solution is used in testing for lignin, a complex organic molecule that bonds to cellulose fibres and strengthens and hardens the cell walls in plants. A positive toluidine blue test causes the solution to turn from blue to pink. A similar test can be performed with phloroglucinol-HCl solution, which turns red.

Dye Content: >80%

Molecular Formula: C15H16ClN3S

Molecular Weight: 305.83 g/mol

Melting Point: 156-158 °C(lit.)

Absorptivity (1%/1cm): >1200 Loss on drying: <8.0%

Solubility (0.1% dist. Water): Clear blue solution

Hazard Phrases: Not considered harmful under normal laboratory conditions

Cas No: 92-31-9
Einecs No: 202-146-2

HS CODE: 32041329


Following the UK’s departure from the EU on 1 January 2021, all European shipments are sent on a DAP Basis (Delivered at Place).

This means that the buyer will be liable for import VAT at their prevailing national rate and for orders over 150€ (including carriage) import duties will become chargeable at your prevailing national rate.

The Duty is ascertained by your national customs authority based on the HS Code of each product. The HS Code is shown in the “European Shipment” section of each product page.


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