DTPA Acid

DTPA Acid

Diethylenetriaminepentaacetic acid for high-stability micronutrient and industrial chelates

Chemical name
Diethylenetriaminepentaacetic acid (DTPA Acid)
CAS Number
67-43-6
Molecular formula
C14H23N3O10
Molecular weight
393.35 g/mol
DTPA acid content
≥ 99.0%
Appearance
White crystalline powder
Chloride (Cl)
≤ 0.01%
Sulfate (SO4)
≤ 0.05%
Iron (Fe)
≤ 0.001%
Chelating capacity
≥ 252 mg CaCO3/g
pH (10 g/L, 25°C)
2.1–2.5

Overview

DTPA Acid (diethylenetriaminepentaacetic acid) is a high-performance aminopolycarboxylic chelating agent designed for strong and stable complexation of multivalent metal ions. It is particularly effective for binding trivalent metals such as iron (Fe³⁺), making it widely used in agriculture, water treatment, and industrial processes.

In its acid form, DTPA provides flexibility for neutralization and formulation into various salt forms (Na5, Na3, and others), allowing formulators to tailor pH and performance characteristics. It delivers excellent chelation efficiency across a broad pH range, especially in neutral to moderately alkaline systems.

DTPA is an octadentate aminopolycarboxylate. Its structure contains five carboxylic acid groups and three nitrogen atoms, enabling formation of very stable metal complexes, especially with Fe³⁺ and other multivalent ions. The acid is typically supplied as a white crystalline powder with limited solubility in water in its protonated form and is commonly neutralized to form soluble sodium salts for practical applications.

Benefits

  • Extremely strong chelation of Fe³⁺ and other multivalent metals
  • High stability constants for metal complexes
  • Versatile intermediate for producing sodium salts (Na3, Na5)
  • Effective across a wide pH range after neutralization
  • Prevents precipitation of metal ions
  • Improves micronutrient stability and availability
  • Widely used and well-established chemistry

Applications

  • Raw material for Fe-DTPA (typically 11% Fe)
  • Fe-DTPA in soils up to approximately pH 7.5
  • Zn, Mn, and Cu chelates
  • Chelate manufacturing with controlled neutralization
  • Scale inhibition and metal-ion control in water treatment
  • Pulp and paper processing
  • Textile processing
  • Cleaning formulations after neutralization
  • Oilfield chemicals

Specifications

  • Chemical name | Diethylenetriaminepentaacetic acid (DTPA Acid)
  • CAS Number | 67-43-6
  • Molecular formula | C14H23N3O10
  • Molecular weight | 393.35 g/mol
  • DTPA acid content | ≥ 99.0%
  • Appearance | White crystalline powder
  • Chloride (Cl) | ≤ 0.01%
  • Sulfate (SO4) | ≤ 0.05%
  • Iron (Fe) | ≤ 0.001%
  • Chelating capacity | ≥ 252 mg CaCO3/g
  • pH (10 g/L, 25°C) | 2.1–2.5

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