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Picrylsulfonic acid solution

5 % (w/v) in H2O, BioReagent, suitable for determination of primary amines

TNBS, 2,4,6-Trinitrobenzenesulfonic acid solution
Empirical Formula (Hill Notation):
CAS Number:
Molecular Weight:
MDL number:
PubChem Substance ID:

Quality Level

product line



5 % (w/v) in H2O


suitable for determination of primary amines

storage temp.


SMILES string




InChI key


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Hydrophilic modifying reagent. Derivatives with amino compounds can be regenerated with hydrazine.


10 mL in amber poly bottle


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Hazard Statements

Hazard Classifications

Acute Tox. 4 Oral - Eye Dam. 1 - Skin Corr. 1B - Skin Sens. 1

Supplementary Hazards

Storage Class Code

8A - Combustible, corrosive hazardous materials

WGK Germany


Flash Point(F)

Not applicable

Flash Point(C)

Not applicable

Certificate of Analysis

Certificate of Origin

  1. Which document(s) contains shelf-life or expiration date information for a given product?

    If available for a given product, the recommended re-test date or the expiration date can be found on the Certificate of Analysis.

  2. How do I get lot-specific information or a Certificate of Analysis?

    The lot specific COA document can be found by entering the lot number above under the "Documents" section.

  3. Is Product P2297, Picrylsulfonic acid solution, supposed to be yellow?

    Yes. This product is a clear to slightly hazy yellow solution at room temperature. The solution has a concentration of 5 w/v % in H2O (5g per 100 mL).

  4. In general, what is Product P2297, Picrylsulfonic acid solution, used for?

    Picrylsulfonic acid has been used 1) As a hydrophilic modifying reagent[1]; 2) To make derivatives with amino compounds, which can be regenerated with hydrazine [2].

  5. How is Product P2297, Picrylsulfonic acid solution, tested? Do you have any references for its use besides Sigma's method?

    Sigma's suitability assay is based on a published method.1 We use a 500-fold dilution as a working solution, with glycine as a standard. Hydrochloric acid is used to stop the reaction, and to reduce yellow background due to picric acid.  Sodium phosphate is used as a buffer in place of sodium bicarbonate to avoid formation of CO2 when HCl is added.  Absorbance is read at 420 nm.Other procedures have been published. For example:---Twenty-five mL of 0.03 M TNBS is added to 1 mL of sample (in borate buffer), agitated to ensure complete mixing, and allowed to stand for 30 minutes at room temperature (25±1°C).  No quenching step is used.  In the blank, buffer replaces sample.  Absorbance is read at 420 nm.2---Protocols using a more concentrated solution of picric acid (1.1 M) have been published.3Note: TNBS forms an orange complex with amines, monitored at 420 nm, but the EmM of the complexes will vary with the reacting group:  for alpha-amino groups, 22.0; for epsilon-amino groups, somewhat lower; and for thiol groups, 2.25.3References:1. Satake, K. et al., J. Biochem., 47, 654 (1960).2. Snyder, S.L. and Sobocinski P.Z., Anal. Biochem., 64, 284-288 (1975).3. Fields, R., Methods in Enzymology, 25, 464-468 (1972).

  6. What are the suggested storage conditions for Product P2297, Picrylsulfonic acid solution?

    Store Product No. P2297 at 2-8°C in the dark.

  7. Is Product P2297, Picrylsulfonic acid solution, considered to be stable?

    It is explosive when it is dry. The solution should be stored at 2-8°C in the dark. Under these conditions less than 5% decomposition will occur over five months. At 37°C, 50% decomposition occurred in 60 days.  Picrylsulfonic acid decomposes to picric acid, crystals of which may form in the solution, but this impurity causes no interference in usage. The solution may also contain a trace amount of 2,4-dinitrophenol (typically <0.5%).  Storage at -20°C may enhance shelf-life of stock solutions.

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  9. What is the Department of Transportation shipping information for this product?

    Transportation information can be found in Section 14 of the product's (M)SDS.To access the shipping information for this material, use the link on the product detail page for the product. 

  10. My question is not addressed here, how can I contact Technical Service for assistance?

    Ask a Scientist here.

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