Overview & Applications: Citrate Phosphate Buffers, McIlvaine Buffer, CPD, and CPDA Solutions

Citrate-phosphate buffer is a highly adaptable buffer solution, composed of citric acid and sodium phosphate. These buffers offer precise pH control in the acidic to neutral range (typically pH 2.6–7.6) and are widely used in biological and biochemical settings for their compatibility with enzymes and proteins.

McIlvaine Buffer

Developed by Theodore McIlvaine in 1921, McIlvaine buffer is a standardized citrate-phosphate buffer system prepared by mixing disodium phosphate and citric acid solutions in varying ratios to produce a broad pH range from ~2.6 to 8.0 [1]. Its clarity, reproducibility, and minimal chemical reactivity make it a preferred buffer in both research and clinical laboratories.

Key Features

  • pH range: 2.6 to 8.0
  • Simple preparation with consistent results
  • Low ionic strength

Applications

  • Enzyme kinetics studies
  • Protein stability tests
  • Histological staining
  • pH calibration and biochemical assays
CAT# Product Name
BB-2468 Citrate Phosphate Buffer (Mcilvaine Buffer, pH 6.0)
BB-2444 Citrate Phosphate Buffer (Mcilvaine Buffer, pH 5.0)
BB-2440 Citrate Phosphate Buffer (Mcilvaine Buffer, pH 4.0)
BB-2436 Citrate Phosphate Buffer (Mcilvaine Buffer, pH 3.0)

Key Features

  • pH range: 2.6 to 8.0
  • Simple preparation with consistent results
  • Low ionic strength

Applications

  • Enzyme kinetics studies
  • Protein stability tests
  • Histological staining
  • pH calibration and biochemical assays

Citrate-Phosphate-Dextrose (CPD) Solution

CPD is an anticoagulant solution consisting of citric acid, sodium citrate, monobasic sodium phosphate, and dextrose. It is formulated specifically for blood preservation, preventing clotting, and providing metabolic support to red blood cells.

Overview_Citrate Phos

Key Features

  • Chelates calcium to prevent clotting
  • Supports red blood cell energy metabolism with dextrose

Applications

  • Blood collection and storage (up to 21 days)
  • Component preparation in transfusion medicine
  • Research involving fresh whole blood

A similar product, Acid-Citrate-Dextrose (ACD) Solution, is routinely used in cell processing, blood storage, platelet collection, laboratory tests and blood-related research labs.

CAT# Product Name
IBB-410 Citrate-Phosphate-Dextrose (CPD) Solution
IBB-400 ACD Solution

Citrate-Phosphate-Dextrose-Adenine (CPD-Adenine, CPDA-1) Solution

Citrate-Phosphate-Dextrose-Adenine Solution is a modified formulation of CPD, with increased Dextrose concentration and the addition of Adenine, a purine nucleobase. These modifications have been found to increase blood viability during storage, specifically after longer-term storage [2].  In addition, Beutler and West found that CPDA-1 is superior for “hard-packed” blood with concentrations of hematocrit greater than 80 percent.

CAT# Product Name
IBB-420 Citrate-Phosphate-Dextrose-Adenine (CPDA-1) Solution