Ash Value Calculator
Total Ash · Acid‑Insoluble Ash · Sulfated Ash
Pharmacopoeial Analysis
Ash Content Calculation
Weights (grams)
Empty crucible after drying
Accurately weighed sample
After incineration to constant weight
Incineration Conditions: 450°C until carbon-free (2-4 hours)
Reference Samples (Pharmacopoeial Standards)
Formula
% Ash = ((W₃ - W₁) / W₂) × 100
W₁ = Crucible weight (g)
W₂ = Sample weight (g)
W₃ = Crucible + Ash weight (g)
Pharmacopoeial Limits
Total Ash
• Herbal drugs: ≤ 15%
• Plant extracts: ≤ 10%
• Senna leaves: ≤ 12%
• Digitalis leaves: ≤ 10%
Acid-Insoluble Ash
• Most herbs: ≤ 5%
• Vegetable drugs: ≤ 2%
• Purified extracts: ≤ 1%
Indicates silica/sand contamination
Sulfated Ash
• Organic substances: ≤ 20%
• Cellulose derivatives: ≤ 0.5%
• Pharmaceutical excipients: varies
Applications
Pharmaceuticals: Purity testing of APIs, excipients, herbal drugs
Food Industry: Mineral content, quality control, adulteration detection
Cosmetics: Purity of natural ingredients, inorganic residues
Research: Marker for digestibility studies (AIA)
Working Mechanism
- 1.Weigh empty crucible (W₁) after drying to constant weight
- 2.Add sample, weigh crucible + sample (total = W₁ + W₂)
- 3.Heat gradually to 100°C to avoid spattering, then incinerate at 450-600°C
- 4.Cool in desiccator, weigh crucible + ash (W₃)
- 5.Calculate: % Ash = ((W₃ - W₁) / W₂) × 100
For acid-insoluble ash: treat total ash with HCl, filter, ignite residue
For sulfated ash: moisten with H₂SO₄ before ignition