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Phosphate Based Blocking Buffers

Product#: PhosphateBasedBlockingBuffers
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verified PBS / PBST Blocking · 0.1 µm Filtration

Phosphate Based Blocking Buffers - Category Selection Guide

Five blocking formulations on two phosphate-buffered bases, ten catalog numbers in 500 ml and 1000 ml. This page is a category reference — pick the formulation your detection chemistry needs and click View for its product page; specifications and selection guidance follow below.

Phosphate Based Blocking Buffers — Catalog · 10 Catalog Numbers Across 5 Product Pages
This page is a category reference, not a product page. Catalog numbers are grouped under the product page they order from; click View once per group.
Cat. No. Base Size
Bovine Serum Albumin (3%) with PBS Blocking Buffer PBS · 2 catalog numbers · 500 ml · 1000 ml
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DCP-BSAPBS3X_500 ml PBS 500 ml
DCP-BSAPBS3X_1000 ml PBS 1000 ml
Bovine Serum Albumin (3%) with PBST Blocking Buffer PBST · 2 catalog numbers · 500 ml · 1000 ml
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DCP-BSAPBST3X_500 ml PBST 500 ml
DCP-BSAPBST3X_1000 ml PBST 1000 ml
Casein (1%) with PBS Blocking Buffer PBS · 2 catalog numbers · 500 ml · 1000 ml
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DCP-CPBS1X_500 ml PBS 500 ml
DCP-CPBS1X_1000 ml PBS 1000 ml
Gelatin (1%) in PBS Blocking Buffer PBS · 2 catalog numbers · 500 ml · 1000 ml
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DCP-GPBS1X_500 ml PBS 500 ml
DCP-GPBS1X_1000 ml PBS 1000 ml
PVP in PBS Blocking Buffer PBS · 2 catalog numbers · 500 ml · 1000 ml
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DCP-PVPPBS1X_500 ml PBS 500 ml
DCP-PVPPBS1X_1000 ml PBS 1000 ml

Not sure which formulation? Compare the blocking agents · See applications by formulation · Read the FAQ

Family Snapshot

What the five formulations share, and where they differ

Phosphate-based blocking buffers provide an effective and versatile option for reducing non-specific binding in various protein detection techniques. Their ability to maintain physiological pH and compatibility with many detection systems make them a popular choice in molecular biology and biochemistry research. However, researchers should consider the specific requirements of their assay when choosing between phosphate-based and other blocking buffer options.

  • Five formulations: Bovine Serum Albumin (3%) with PBS, Bovine Serum Albumin (3%) with PBST, Casein (1%) with PBS, Gelatin (1%) in PBS, and PVP in PBS.
  • Two phosphate-buffered bases: PBS and PBST, as published in the product names.
  • Why phosphate: the source credits the ability to maintain physiological pH and compatibility with many detection systems.
  • Appearance: Clear, Colorless Liquid.
  • Sterility: Nonsterile; 0.1 µm membrane filtration (single step).
  • Fill sizes: every formulation is stocked in 500 ml and 1000 ml — ten catalog numbers in total.
  • Selection basis: the source advises weighing the specific requirements of the assay when choosing between phosphate-based and other blocking buffer options.
PBS / PBST 0.1 µm RUO
CATEGORY REFERENCE · PHOSPHATE BASED BLOCKING BUFFERS
The published specification, in the source’s own values
  • CategoryPhosphate Based Blocking Buffers
  • Buffer bases stockedPBS, PBST
  • Formulations5
  • Catalog numbers10
  • Fill sizes500 ml, 1000 ml
  • AppearanceClear, Colorless Liquid
  • Filtration0.1 µm membrane filtration (single step)
  • Blocking agentsBSA 3%, Casein 1%, Gelatin 1%, PVP
  • pHphysiological (value not stated)
Why The Blocking Agent Matters

Same base, different blocker, different blot

All five formulations sit on a phosphate base, so the variable a buyer is actually choosing is the blocking agent. The published immunoassay literature is consistent on one point: that choice is not cosmetic. Each literature statement below is cited to the reference list at the foot of the page.

blur_on

Non-specific binding is the target

The source describes these buffers as an effective and versatile option for reducing non-specific binding in various protein detection techniques.

science

The phosphate base holds physiological pH

The source attributes the popularity of this family in molecular biology and biochemistry research to its ability to maintain physiological pH and its compatibility with many detection systems.

compare_arrows

The blocker changes what you detect

A direct comparison of serum albumin, non-fat dry milk and Tween 20 on nitrocellulose found quantitative and qualitative differences in the antigens detected, and recommended comparing several blocking and washing methods rather than assuming one.[2]

bar_chart

Blocking efficiency differs by agent

On polystyrene plates, casein and instantized milk suppressed non-specific binding by over 90 % at far lower concentrations than most of eight other proteins; enzymatically hydrolyzed porcine-skin gelatin was the least effective protein tested.[3]

warning

Casein is itself a phosphoprotein

Casein is the primary blocking protein of non-fat dry milk and is a phosphoprotein, which is why casein-based blocking is reported as unsuitable for phospho-specific antibodies.[7]

tune

A protein-free route exists

Polyvinylpyrrolidone was described as a blocking agent for immunochemical work precisely because it is not a protein[4]; it is also a blocking component of Denhardt’s hybridization solution.[5]

The one decision this page exists to support

The source says to weigh the specific requirements of the assay when choosing between phosphate-based and other blocking buffers — and the literature says where that bites hardest: a casein blocker and a phospho-specific antibody are a documented mismatch[7], and a purified single protein such as BSA carries its own caveat that preparations differ and need a blocking control.[6]

0.1 µm
Filtration membrane
1
Filtration step
10
catalog numbers across 5 product pages, in 500 ml and 1000 ml
Filtration

0.1 µm membrane filtration

0.1 µm filtration removes large particulates and aggregates, helping protect downstream applications.

  1. 1

    0.1 µm Membrane Filtration

    Removes large particulates and aggregates, helping protect downstream applications.

Lot documentation. Confirm filtration on the Certificate of Analysis for the lot you receive, or ask support@diagnocine.com.
Blocking Agent Reference

The stocked agents, and what the literature records about each

The source does not publish a comparison table for this family, so the table below pairs each stocked formulation with the published characterization of its blocking agent. Every literature entry is cited; nothing in the “Formulation” column has been altered from the catalog.

Formulation (as stocked) Agent class What the published literature records Watch-out
Bovine Serum Albumin (3%) with PBS Blocking Buffer Single purified protein Serum albumin is one of the standard blockers benchmarked against milk, casein and gelatin on plates and on nitrocellulose.[2,3] BSA preparations are not interchangeable: non-specific binding has been traced to the BSA preparation itself, so a blocking-agent control is advised.[6]
Bovine Serum Albumin (3%) with PBST Blocking Buffer Single purified protein on a Tween-containing base The non-ionic detergent Tween 20 was itself introduced as a means of blocking unoccupied protein-binding sites on nitrocellulose.[1] Tween 20 used alone as the blocking agent has been reported to give artefactual results, so it is normally paired with a protein blocker.[9]
Casein (1%) with PBS Blocking Buffer Milk phosphoprotein Casein and instantized milk were the most effective proteins tested for suppressing non-specific binding, blocking by over 90 % at far lower concentrations than most alternatives.[3] Casein is a phosphoprotein; casein-based blocking is reported as unsuitable for phospho-specific antibodies.[7]
Gelatin (1%) in PBS Blocking Buffer Denatured collagen Blocking performance depends strongly on the gelatin source: fish-skin gelatin blocked far better than enzymatically hydrolyzed porcine-skin gelatin, the weakest protein in the series.[3] The source does not state the gelatin origin for this catalog item. Confirm it before applying a literature figure.
PVP in PBS Blocking Buffer Synthetic polymer, protein-free Polyvinylpyrrolidone was characterized as a blocking agent for immunochemical studies[4], and is a blocking component of Denhardt’s membrane-hybridization solution.[5] The source does not state a PVP concentration for this catalog item, while the other four formulations carry one.
One clarification beyond the source (delete if unwanted). Inorganic phosphate is a strong competitive inhibitor of alkaline phosphatase[8], and antibody-supplier guidance prefers TBS or TBST with AP-labeled antibodies because PBS interferes with the AP signal.[10] If your detection uses an AP conjugate, this is the “specific requirement of the assay” the source asks you to weigh; Diagnocine’s Tris Based Blocking Buffers family covers that case.
Applications by Formulation

Which formulation for which detection chemistry

The source assigns applications to the category as a whole, not to individual formulations. Each tab therefore states the source’s own category-level use first, then the published characterization of that blocking agent, cited.

Bovine Serum Albumin (3%) · PBS
  • Reducing non-specific binding in various protein detection techniques (source).
  • Anti-phosphoprotein antibodies: supplier guidance names BSA as the preferred blocker[10], and casein-based blocking is reported as unsuitable for phospho-specific antibodies.[7]
  • Run a blocking-agent control: non-specific binding has been traced to the BSA preparation itself.[6]
Bovine Serum Albumin (3%) · PBST · Tween-containing base
  • Reducing non-specific binding in various protein detection techniques (source).
  • Protocols that keep a non-ionic detergent in the blocking step; Tween 20 was introduced as a way of blocking unoccupied protein-binding sites on nitrocellulose.[1]
  • Tween 20 used alone as the blocking agent has been reported to produce artefactual results.[9]
Casein (1%) · PBS · strongest blocker in the series
  • Reducing non-specific binding in various protein detection techniques (source).
  • General protein detection where blocking strength is the priority: casein blocked non-specific binding by over 90 % at far lower concentrations than most of eight other proteins tested.[3]
  • Not the formulation for phospho-specific antibodies — casein is itself a phosphoprotein.[7]
Gelatin (1%) · PBS · denatured collagen
  • Reducing non-specific binding in various protein detection techniques (source).
  • An alternative when albumin- or milk-derived blockers cross-react with the probe; gelatin sits in the same benchmarked series as albumin, casein and milk.[3]
  • Published performance is source-dependent: fish-skin gelatin blocked far better than enzymatically hydrolyzed porcine-skin gelatin.[3] The source does not state which gelatin this item uses.
PVP · PBS · protein-free
  • Reducing non-specific binding in various protein detection techniques (source).
  • Workflows in which every protein blocker is a potential cross-reactant: polyvinylpyrrolidone was characterized as a blocking agent for immunochemical studies precisely because it is not a protein.[4]
  • Membrane-hybridization lineage: PVP is a blocking component of Denhardt’s solution.[5]
Product Comparison

The five formulations side by side

Every value in this table is reproduced from the catalog exactly as published.

Product Blocking agent Base Catalog numbers Sizes
Bovine Serum Albumin (3%) with PBS Blocking Buffer Bovine Serum Albumin (3%) PBS DCP-BSAPBS3X_500 ml
DCP-BSAPBS3X_1000 ml		 500 ml, 1000 ml
Bovine Serum Albumin (3%) with PBST Blocking Buffer Bovine Serum Albumin (3%) PBST DCP-BSAPBST3X_500 ml
DCP-BSAPBST3X_1000 ml		 500 ml, 1000 ml
Casein (1%) with PBS Blocking Buffer Casein (1%) PBS DCP-CPBS1X_500 ml
DCP-CPBS1X_1000 ml		 500 ml, 1000 ml
Gelatin (1%) in PBS Blocking Buffer Gelatin (1%) PBS DCP-GPBS1X_500 ml
DCP-GPBS1X_1000 ml		 500 ml, 1000 ml
PVP in PBS Blocking Buffer PVP (concentration not stated in source) PBS DCP-PVPPBS1X_500 ml
DCP-PVPPBS1X_1000 ml		 500 ml, 1000 ml
FAQ

Frequently asked questions

The questions that come up when a purchasing decision meets a detection chemistry.

The blocking agent is carried on a phosphate-buffered saline base (PBS or PBST). According to the source, phosphate-based blocking buffers are an effective and versatile option for reducing non-specific binding in various protein detection techniques, and their ability to maintain physiological pH and compatibility with many detection systems make them a popular choice in molecular biology and biochemistry research.
Plan for it before you start. Inorganic phosphate is a strong competitive inhibitor of alkaline phosphatase[8], and antibody-supplier guidance prefers TBS or TBST with AP-labeled antibodies because PBS interferes with the AP signal.[10] The source itself advises weighing the specific requirements of the assay when choosing between phosphate-based and other blocking buffer options. Diagnocine lists a separate Tris Based Blocking Buffers family for that case.
Not the casein formulation. Casein is the primary blocking protein of non-fat dry milk and is itself a phosphoprotein, which is why casein-based blocking is reported as unsuitable for phospho-specific antibodies.[7] Supplier guidance names BSA as the preferred blocker for anti-phosphoprotein antibodies.[10]
They are two separate catalog items with the same blocking agent, Bovine Serum Albumin (3%), on two different bases: PBS and PBST. PBST carries the non-ionic detergent Tween 20, which was itself introduced as a way of blocking unoccupied protein-binding sites on nitrocellulose.[1] Tween 20 used alone as the blocking agent has been reported to produce artefactual results, so it is normally paired with a protein blocker.[9]
These buffers are nonsterile and filtered once through a 0.1 micron membrane, which removes large particulates and aggregates, helping protect downstream applications. The solution is described as a Clear, Colorless Liquid. Confirm against the Certificate of Analysis for the lot you receive.
When any protein in the blocking solution could cross-react with the probe. Polyvinylpyrrolidone was described as a blocking agent for immunochemical studies precisely because it is not a protein[4], and it is a blocking component of Denhardt's membrane-hybridization solution.[5] The source does not state a PVP concentration for this catalog item, so ask before assuming one.
Every formulation is stocked in 500 ml and 1000 ml, giving ten catalog numbers across five product pages: DCP-BSAPBS3X, DCP-BSAPBST3X, DCP-CPBS1X, DCP-GPBS1X and DCP-PVPPBS1X, each with a _500 ml and a _1000 ml suffix. The catalog table at the top of this page groups them under the product page they order from.
Key References

Supporting literature on blocking agents

The Diagnocine source description carries no citation list of its own. The sources below are the ones cited in the sections above; each was checked against its published record before it was listed.

  1. Batteiger B, Newhall WJ 5th, Jones RB (1982). The use of Tween 20 as a blocking agent in the immunological detection of proteins transferred to nitrocellulose membranes. J Immunol Methods 55(3):297–307. doi:10.1016/0022-1759(82)90089-8
  2. Spinola SM, Cannon JG (1985). Different blocking agents cause variation in the immunologic detection of proteins transferred to nitrocellulose membranes. J Immunol Methods 81(1):161–165. doi:10.1016/0022-1759(85)90132-2
  3. Vogt RF Jr, Phillips DL, Henderson LO, Whitfield W, Spierto FW (1987). Quantitative differences among various proteins as blocking agents for ELISA microtiter plates. J Immunol Methods 101(1):43–50. doi:10.1016/0022-1759(87)90214-6
  4. Haycock JW (1993). Polyvinylpyrrolidone as a blocking agent in immunochemical studies. Anal Biochem 208(2):397–399. doi:10.1006/abio.1993.1068
  5. Denhardt DT (1966). A membrane-filter technique for the detection of complementary DNA. Biochem Biophys Res Commun 23(5):641–646. doi:10.1016/0006-291X(66)90447-5
  6. Xiao Y, Isaacs SN (2012). Enzyme-linked immunosorbent assay (ELISA) and blocking with bovine serum albumin (BSA) — not all BSAs are alike. J Immunol Methods 384(1–2):148–151. doi:10.1016/j.jim.2012.06.009
  7. Galva C, Gatto C, Milanick M (2012). Soymilk: an effective and inexpensive blocking agent for immunoblotting. Anal Biochem 426(1):22–23. doi:10.1016/j.ab.2012.03.028
  8. Kim EE, Wyckoff HW (1991). Reaction mechanism of alkaline phosphatase based on crystal structures. Two-metal ion catalysis. J Mol Biol 218:449–464. doi:10.1016/0022-2836(91)90724-K
  9. Bird CR, Gearing AJH, Thorpe R (1988). The use of Tween 20 alone as a blocking agent for immunoblotting can cause artefactual results. J Immunol Methods 106(2):175–179.
  10. Bio-Rad Laboratories. Immunodetection (western blotting technical guide, Bio-Rad Antibodies). — Supplier guidance on TBS/TBST with AP-labeled antibodies and BSA for anti-phosphoprotein antibodies.
Formulation selection support. For help matching a blocking formulation to a specific protocol, for the gelatin source or PVP concentration behind a catalog item, or for documentation requests, contact support@diagnocine.com. Ready to order? Back to the Phosphate Based Blocking Buffers catalog.

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