Nonfat Milk Based Blocking Buffer
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- See the table below
Nonfat Milk Based Blocking Buffer
Six ready-to-use 5 % nonfat milk formulations — dairy or soy, on four buffer bases — in two fill sizes. This is a category page, not a product page; open the formulation you need with View.
| Name | Cat. No. | Size | Product Page |
|---|---|---|---|
| 5% Nonfat Dry Milk with ProClin 300 and TBS (1X)Nonfat dry milk · Tris base | DCP-DMB01_500 ml | 500 ml | Viewarrow_forward |
| 5% Nonfat Dry Milk with ProClin 300 and TBS (1X)Nonfat dry milk · Tris base | DCP-DMB01_1000 ml | 1000 ml | Viewarrow_forward |
| 5% Nonfat Dry Milk with ProClin 300 and PBS (1X)Nonfat dry milk · phosphate base | DCP-DMB02_500 ml | 500 ml | Viewarrow_forward |
| 5% Nonfat Dry Milk with ProClin 300 and PBS (1X)Nonfat dry milk · phosphate base | DCP-DMB02_1000 ml | 1000 ml | Viewarrow_forward |
| 5% Nonfat Dry Milk with ProClin 300 and PBST (1X)Nonfat dry milk · phosphate base with detergent | DCP-DMB03_500 ml | 500 ml | Viewarrow_forward |
| 5% Nonfat Dry Milk with ProClin 300 and PBST (1X)Nonfat dry milk · phosphate base with detergent | DCP-DMB03_1000 ml | 1000 ml | Viewarrow_forward |
| 5% Nonfat Dry Milk with ProClin 300 and TBST (1X)Nonfat dry milk · Tris base with detergent | DCP-DMB04_500 ml | 500 ml | Viewarrow_forward |
| 5% Nonfat Dry Milk with ProClin 300 and TBST (1X)Nonfat dry milk · Tris base with detergent | DCP-DMB04_1000 ml | 1000 ml | Viewarrow_forward |
| 5% Nonfat Soy Milk with ProClin 300 and TBS (1X)Nonfat soy milk · Tris base | DCP-DMB05_500 ml | 500 ml | Viewarrow_forward |
| 5% Nonfat Soy Milk with ProClin 300 and TBS (1X)Nonfat soy milk · Tris base | DCP-DMB05_1000 ml | 1000 ml | Viewarrow_forward |
| 5% Nonfat Soy Milk with ProClin 300 and PBS (1X)Nonfat soy milk · phosphate base | DCP-DMB06_500 ml | 500 ml | Viewarrow_forward |
| 5% Nonfat Soy Milk with ProClin 300 and PBS (1X)Nonfat soy milk · phosphate base | DCP-DMB06_1000 ml | 1000 ml | Viewarrow_forward |
Dairy or soy, and which base? Compare the six formulations · See applications by formulation · Read the FAQ
What nonfat milk blocks, and what changes between the six
Nonfat milk based blocking buffers are commonly used reagents in Western blotting and other immunoassay techniques. The primary function of nonfat milk based blocking buffer is to reduce non-specific binding of antibodies to the membrane, thereby decreasing background noise and improving signal-to-noise ratio in Western blots and other immunoassays. These work well with a wide range of antibodies and detection methods. Nonfat milk often provides the lowest background, especially on nitrocellulose membranes. These products contain ProClin 300 which helps maintain the integrity of the solution, preventing microbial growth. ProClin 300 is more effective than sodium azide as a preservative. Sodium Azide interferes with enzymatic activities such as phosphatase/Peroxidase used in blotting experiments, while ProClin 300 does not interfere and is compatible with enzymes and antibodies used in diagnostic assay.
- Six ready-to-use formulations, all at 5 % and all preserved with ProClin 300.
- Two blocking proteins: nonfat dry milk in four of the six, nonfat soy milk in two.
- Four buffer bases across the family: TBS, PBS, PBST, and TBST.
- Lowest background is the stated strength of nonfat milk, especially on nitrocellulose membranes.
- Broad compatibility: the buffers work well with a wide range of antibodies and detection methods.
- ProClin 300 rather than sodium azide, because azide interferes with enzymes used in blotting while ProClin 300 does not.
- Two fill sizes per formulation: 500 ml and 1000 ml, twelve catalog numbers in total.
- pH 7.4, stored at 4 °C, filtered 0.1 µm twice and 0.04 µm twice. Customization available on inquiry.
- Formulations in this family6
- Catalog numbers12 (6 formulations × 2 sizes)
- Blocking agent concentration5 %
- Blocking proteins offerednonfat dry milk (4) · nonfat soy milk (2)
- Buffer bases across the familyTBS, PBS, PBST, TBST
- PreservativeProClin 300
- Fill sizes500 ml, 1000 ml
- pH7.4
- Storage4 °C
- Sterility0.1 µm ×2, 0.04 µm ×2
Ready-to-use, preserved, and offered on four bases
All six carry 5 % blocking protein and ProClin 300. What differs is which protein does the blocking, and which buffer the protein sits in.
Background down, signal-to-noise up
The primary function is to reduce non-specific binding of antibodies to the membrane, which decreases background noise and improves the signal-to-noise ratio in Western blots and other immunoassays.
The low-background default
Nonfat milk often provides the lowest background, especially on nitrocellulose membranes — which is why it is the usual first blocker to try before anything more specialized is brought in.
Broad antibody and detection compatibility
These buffers work well with a wide range of antibodies and detection methods, so one bottle usually covers routine blotting rather than one assay.
Preserved, so it keeps
ProClin 300 helps maintain the integrity of the solution and prevents microbial growth. It is a widely used in-vitro-diagnostic biocide, effective at very low concentrations, offered as a replacement for thimerosal, sodium azide, and gentamicin.[1,2]
Preserved without poisoning the read-out
Sodium azide interferes with enzymatic activities used in blotting, while ProClin 300 does not interfere and is compatible with enzymes and antibodies used in diagnostic assays. Azide is a documented horseradish peroxidase inhibitor; ProClin 300 is reported compatible with enzyme systems including HRP.[3,4]
A non-dairy option in the same family
Two of the six formulations use nonfat soy milk instead of nonfat dry milk. Soymilk has been evaluated as a blocking agent for immunoblotting and reported to give a high signal-to-noise ratio with short blocking times.[8]
Two decisions, then you are done
First, the blocking protein: dairy nonfat dry milk, or nonfat soy milk. Second, the buffer base: TBS or PBS, with or without detergent. The concentration, the preservative, the pH, the filtration, and the storage temperature are the same across all six, so nothing else has to be re-validated when you switch between them.
Four membrane passes, two of them sub-0.1 µm
The source specifies one sterility process for all six formulations: filtered 0.1 µm twice and 0.04 µm twice, in a sterile environment — two coarse passes followed by two sub-0.1 µm polishing passes.
-
1
0.1 µm Pre-filtration I
First 0.1 µm membrane pass. Removes bulk particulates and the microbial load carried in from raw materials and make-up water before any polishing step sees the solution.
-
2
0.04 µm Pre-filtration II
First sub-0.1 µm pass. Takes out the fine fraction a 0.1 µm or 0.2 µm membrane lets through — the undissolved milk-solid range that produces a speckled background when it lands on a membrane.[7]
-
3
0.1 µm Sterile-filtration I
Second 0.1 µm pass, performed in a sterile environment. This is the sterilizing step of the sequence rather than a clarifying one.
-
4
0.04 µm Sterile-filtration II — Final Polish
Second sub-0.1 µm pass, immediately before fill. The final polish is what distinguishes this architecture from a conventional single-membrane sterile filtration.
Why a milk blocker in particular benefits from the polish
Milk solutions made up at the bench are routinely filtered before use, because undissolved particulates bind to the membrane and produce a speckled background across the whole blot.[7] A four-pass architecture applied at manufacture removes that step — and the variability that comes with doing it by hand — from the protocol.
Six formulations, by blocking protein and base
Concentration, preservative, pH, filtration, and storage are constant across the family. The table reports only what each catalog name states.
| Formulation | Blocking protein | Buffer base | Detergent | Catalog numbers |
|---|---|---|---|---|
| DCP-DMB01 | Nonfat dry milk | TBS — Tris | cancel Not indicated | DCP-DMB01_500 ml DCP-DMB01_1000 ml |
| DCP-DMB02 | Nonfat dry milk | PBS — phosphate | cancel Not indicated | DCP-DMB02_500 ml DCP-DMB02_1000 ml |
| DCP-DMB03 | Nonfat dry milk | PBS — phosphate | check_circle Indicated by PBST[6] | DCP-DMB03_500 ml DCP-DMB03_1000 ml |
| DCP-DMB04 | Nonfat dry milk | TBS — Tris | check_circle Indicated by TBST[6] | DCP-DMB04_500 ml DCP-DMB04_1000 ml |
| DCP-DMB05 | Nonfat soy milk | TBS — Tris | cancel Not indicated | DCP-DMB05_500 ml DCP-DMB05_1000 ml |
| DCP-DMB06 | Nonfat soy milk | PBS — phosphate | cancel Not indicated | DCP-DMB06_500 ml DCP-DMB06_1000 ml |
Which of the six belongs in which workflow
The source names Western blotting and other immunoassay techniques. Notes below that go beyond the source are footnoted to their external authority.
- Reducing non-specific binding of antibodies to the membrane in Western blotting.
- Other immunoassay techniques where background noise limits the signal-to-noise ratio.
- Routine blotting across a wide range of antibodies and detection methods.
- Nitrocellulose membranes in particular, where nonfat milk often gives the lowest background.
- Two well-documented exceptions apply to any dairy-milk blocker: phospho-specific antibodies, because milk carries the phosphoprotein casein, and avidin–biotin detection, because milk carries endogenous biotin. Practice is not unanimous — at least one major antibody manufacturer reports no such interference using freshly made milk — so validate against your own antibody datasheet.[7]
- The same family-level use — reducing non-specific antibody binding on the membrane — with a non-dairy blocking protein.
- Soymilk has been evaluated against nonfat dry milk and a commercial blocker for immunoblotting, and nonfat soymilk was reported to give a high signal-to-noise ratio with the shortest blocking times.[8]
- Available on the Tris base (DCP-DMB05) and the phosphate base (DCP-DMB06); no detergent-containing soy configuration is listed.
- Where a dairy-derived blocker is unsuitable for the antibody or the detection chemistry, this is the in-family alternative to try before moving to a different blocker class.
- Alkaline phosphatase conjugate: choose a TBS-based formulation, because PBS interferes with AP activity.[5]
- Horseradish peroxidase conjugate: either base is in common use; the relevant point here is the preservative, and ProClin 300 is documented as compatible with enzyme systems including HRP.[2]
- Detergent already present: DCP-DMB03 (PBST) and DCP-DMB04 (TBST). A small amount of Tween-20 in blocking and washing solutions reduces background staining; the resulting buffers are the ones written PBST and TBST.[6]
- The source does not state the detergent identity or its concentration in the PBST and TBST formulations — request the Certificate of Analysis for the actual value.
- Blocker concentration is a variable worth titrating: too little leaves background, too much can mask the antibody–antigen interaction or inhibit the marker enzyme.[5]
Identical across all six formulations
Only the blocking protein and the buffer base change between catalog lines. Everything below is common to all twelve catalog numbers.
| Attribute | Specification, as stated by the source |
|---|---|
| Blocking agent | Nonfat milk at 5 % — nonfat dry milk or nonfat soy milk |
| Primary function | Reduce non-specific binding of antibodies to the membrane |
| Effect | Decreased background noise; improved signal-to-noise ratio |
| Compatibility | Works well with a wide range of antibodies and detection methods |
| Membrane note | Nonfat milk often provides the lowest background, especially on nitrocellulose membranes |
| Preservative | ProClin 300 — maintains the integrity of the solution and prevents microbial growth |
| Fill sizes | 500 ml and 1000 ml |
| pH | 7.4 |
| Storage | 4 °C |
| Sterility | Filtered 0.1 µm twice and 0.04 µm twice, in a sterile environment |
| Customization | Other concentrations; additions of chemicals, compounds, proteins, or supplements; different pH; further modifications — on inquiry |
| Intended use | Research Use Only (RUO) |
Questions this catalog gets asked
Primary literature and cited sources
The source description carries no citation or reference list. The entries below are supporting literature for the technique the source names, followed by the external technical sources footnoted on this page. No DOI is shown where one could not be confirmed — none has been invented.
Supporting Literature
- Towbin H, Staehelin T, Gordon J. Electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets: procedure and some applications. Proceedings of the National Academy of Sciences USA. 1979;76(9):4350–4354. — the founding Western blot method, the technique this family is written for.
- Johnson DA, Gautsch JW, Sportsman JR, Elder JH. Improved technique utilizing nonfat dry milk for analysis of proteins and nucleic acids transferred to nitrocellulose. Gene Analysis Techniques. 1984;1(1):3–8. doi:10.1016/0735-0651(84)90049-9 — the report that introduced nonfat dry milk as a blocking reagent.
Footnoted Technical Sources
- Sigma-Aldrich / Merck. ProClin preservatives — highly effective biocides for controlling microorganisms in reagents intended for in vitro diagnostic use, offered as a replacement for thimerosal, sodium azide, and gentamicin. sigmaaldrich.com
- Sigma-Aldrich / Merck. ProClin preservatives brochure — efficacy versus thimerosal and sodium azide, active at 6–20 ppm, and the Krebs-cycle mechanism of action. sigmaaldrich.com (PDF)
- Sigma-Aldrich. Peroxidase Enzymes technical article — sodium azide listed among the inhibitors of horseradish peroxidase. sigmaaldrich.com
- Thermo Fisher Scientific. Enzyme Probes — the published inhibitor lists for horseradish peroxidase (cyanides, sulfides, azides) and for alkaline phosphatase (cysteine, cyanides, arsenate, inorganic phosphate, divalent-cation chelators). thermofisher.com
- Thermo Fisher Scientific. Blocking Buffers for Western Blot and ELISA — select a TBS-based blocking buffer with alkaline phosphatase conjugates because PBS interferes with AP activity; and the effect of too little or too much blocker. thermofisher.com
- Bio-Rad. Western Blotting: Immunodetection — Blocking and Antibody Incubation; Tween-20 added to blocking and washing solutions to reduce background staining, giving PBST or TBST. bio-rad-antibodies.com
- Advansta. Western Blotting: Blocking Buffers — milk solutions should be filtered to prevent particulates causing a speckled background, and the documented milk caveats for phosphorylated targets and avidin–biotin detection. advansta.com
- Soymilk as a blocking agent for immunoblotting — published comparison of whole soymilk, nonfat soymilk, a commercial blocker, and nonfat milk, reporting superior blocking efficacy for nonfat soymilk in signal-to-noise ratio and blocking time. researchgate.net
