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Blocker BLOTTO Blocking Buffer

Nonfat milk blocking solution for plate- or membrane-based assays.

Blocker BLOTTO Blocking Buffer

Thermo Scientific Blocker BLOTTO Blocking Buffer is a ready-to-use 5% solution of nonfat powdered milk in Tris-buffered saline for Western blot, ELISA, IHC and other detection methods.


  • Popular – nonfat milk has been used for many years in a variety of protein methods, although it is not recommended for avidin-based techniques because it contains some endogenous biotin
  • Convenient – supplied as a ready-to-use 1X TBS solution; can be diluted as needed
  • Easy to use – formulated with anti-foaming agent and thimerosal-free preservative
  • Flexible – may be used for multiple applications, including as a diluent for antibody

Product Details:

The purpose of the blocking step in an assay is to improve assay sensitivity by reducing background interference. However, unforeseen cross-reaction of detection reagents with blocking buffers is itself a cause of high background and low signal-to-noise ratios in assay systems. Because individual blocking buffers are not compatible with every system, a variety of blockers in both Tris-buffered saline (TBS) and phosphate-buffered saline (PBS) are available. The best blocking buffer for a specific experiment will bind to all potential sites of nonspecific interaction, eliminating background without altering or obscuring the epitope for antibody binding.

To optimize the blocking step for a particular immunoassay, empirical testing is essential. Using inadequate amounts of blocker will result in excessive background. Using an excessive blocker concentration can mask antibody-antigen interactions or inhibit the marker enzyme. For best results when developing a new immunoassay, test several different blocking agents for the highest signal-to-noise ratio in the assay. There is no single blocking agent that is ideal for every occasion because many factors can influence nonspecific binding, including various protein interactions unique to a specific assay system.


  1. Alegria-Schaffer, A., et al. (2009). Performing and optimizing Western blots with an emphasis on chemiluminescent detection. Methods Enzymol. 463:573-99.
  2. Abrams, E.T., et al. (2003). J. Immunol. 170:2759-64.
  3. Goretzki, L., et al. (2000). J. Biol. Chem. 275:28625-33.

Related Resources:

Blocking buffers for Western blot and ELISA -- technical guide
Blocking strategies for immunohistochemistry -- technical guide

Related Products:

Pierce Clear Milk Blocking Buffer (10X)
All Blocking Buffers

Ordering Information
Product # Description Pkg. Size Instructions MSDS CofA Price
37530 Blocker BLOTTO in TBS
Formulation: 5% (w/v) nonfat powdered milk in Tris-buffered saline, pH 7.4, with 0.01% Anti-foam A and Kathon preservative
Sufficient For: 150 blots or microplates at 1% and 30mL each
1L Product Instructions for product #37530 Blocker BLOTTO in TBS MSDS for product #37530 Blocker BLOTTO in TBS Certificate of Analysis for product #37530 Blocker BLOTTO in TBS $111.00

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Instructions | MSDS | CofA
Product Instructions | MSDS | CofA  

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