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P2297 Sigma

Picrylsulfonic acid solution

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

Synonym: 2,4,6-Trinitrobenzenesulfonic acid solution, TNBS



Related Categories General Protein Quantitation, Molecular Biology, Protein Quantitation, Proteomics, Quantitation Kits and Reagents More...
product line   BioReagent
concentration   5 % (w/v) in H2O
suitability   suitable for determination of primary amines
storage temp.   2-8°C


Frequently Asked Questions

Frequently Asked Questions are available for this Product.


10 mL in amber poly bottle


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

Price and Availability

Amplified Detection

Direct Detect Infrared Spectrometer
Safety & Documentation

Safety Information

Signal word 
Hazard statements 
Precautionary statements 
Supplemental Hazard Statements 
Explosive when dry.
UN 3265 8 / PGII
WGK Germany 


Certificate of Analysis

Certificate of Origin

Frequently Asked Questions

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. These documents are located on the product detail page under Useful Links & Tools. Click on the following link to search for a Certificate of Analysis. Please click the following link to see the details on our Product Dating Information.
How do I get lot-specific information or a Certificate of Analysis?
A Certificate of Analysis is available by lot number and can be obtained through our Advanced Search Option: http://www.sigmaaldrich.com/catalog/AdvancedSearchPage.do
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).
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]. For the two cited references, please click on the link to the product detail page: http://www.sigmaaldrich.com/catalog/search/ProductDetail/SIGMA/P2297
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.3 Note: 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, 2.25.3 References: 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).
What are the suggested storage conditions for Product P2297, Picrylsulfonic acid solution?
Store Product No. P2297 at 2-8°C in the dark.
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.
How do I find price and availability?
There are several ways to find pricing and availability for our products.  Once you log onto our website, you will find the price and availability displayed on the product detail page. You can contact any of our Customer Sales and Service offices to receive a quote.  USA customers:  1-800-325-3010 or view local office numbers. 
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, or search here. 
My question is not addressed here, how can I contact Technical Service for assistance?
Use the option to the right to "Ask a Question" by email of a Technical Service Scientist.
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