Here are detailed specs for Citric Acid (C₆H₈O₇) — a friendly little tricarboxylic acid used widely in food, pharma, cleaning & industrial uses. If you tell me which “grade” you need (food, pharmaceutical, technical/industrial) I can pull the exact spec sheet for that too.
✅ Basic Physical & Chemical Data
- Chemical formula: C₆H₈O₇ (anhydrous form).
- CAS number: 77-92-9.
- Appearance: White (or almost white) crystalline powder or granules.
- Odour: Essentially odourless (or very faint).
- Density (anhydrous): ~1.66 g/cm³.
- Melting point: ~153-156 °C for anhydrous form; above this it may decompose.
- Solubility: Very soluble in water. For example solubility is ~62 g/100g water at 25 °C.
- pKa values (triprotic acid): ~3.13, 4.76, 6.39.
🏷 Grades & Key Specification Data
Different grades have different purity, water content, allowed impurities, etc. Here are examples:
Food grade (e.g., for anhydrous & monohydrate)
From one source:
- Appearance: White or almost white crystalline powder or granules.
- Assay (citric acid content): ~99.5-100.5% for both anhydrous and monohydrate.
- Water: For anhydrous: ≤ 0.5%; for monohydrate: water ~7.5-8.8%.
- Sulfated ash (residue on ignition): ≤ 0.05% for both.
- Heavy metals, lead, arsenic, etc: e.g. lead ≤ 0.5 mg/kg; arsenic ≤ 1.0 mg/kg.
Technical/Industrial grade
For example:
- Assay: 99.50-100.50% for anhydrous in one spec.
- Water (moisture): max 0.50% (for the anhydrous technical grade)
- Storage: shelf life given as 1,825 days (about 5 years) if stored <30 °C in dry conditions.
Example of a technical-grade solution specification
From a spec sheet:
- Appearance: Clear, water white to pale slightly hazy solution.
- Actives: 50% citric acid (in solution)
- Specific gravity: 1.241 (for 50% solution)
- Solubility: Fully soluble in water
📋 Typical Specification Table (for anhydrous food/technical grade)
| Parameter | Typical Value / Limit |
|---|---|
| Assay (Citric acid) | ~ 99.5-100.5% |
| Water/moisture | ≤ 0.5% (anhydrous) / ~7.5-8.8% (monohydrate) |
| Sulfated ash | ≤ 0.05% |
| Lead | ≤ 0.5 mg/kg |
| Arsenic | ≤ 1.0 mg/kg |
| Appearance | White crystalline powder or granules |
| Odour | Odourless or very slight |
| Solubility | Very soluble in water |
| Storage | Keep in a dry, cool place (<30 °C) |
🔍 Important Notes / Practical Considerations
- “Anhydrous” vs “monohydrate”: The monohydrate form includes a water molecule; the anhydrous form does not. From source: monohydrate form can be converted to anhydrous by heating to about 78 °C.
- Depending on your application (food, pharmaceutical, industrial), you must pick the correct grade. For example, a “technical grade” may not be certified for food use.
- Storage: Because citric acid is hygroscopic (especially in certain forms) and may absorb moisture, store in dry conditions. Also elevated humidity or temperature will affect shelf life.
- When using in process/production (cleaning agents, pH adjustment, chelation, etc) you might get “solution” forms (e.g., 50% citric acid solutions) with distinct specs (specific gravity, active content) rather than just solid powder.
- Ensure you check the supplier’s certificate of analysis (CoA) for each batch — impurities like heavy metals, moisture, ash content can vary.
- If using for food or pharma: ensure compliance with relevant pharmacopeia (USP, BP), food chemical codex (FCC), and regulatory certifications (HACCP, GMP) depending on jurisdiction.
If you like, I can pull up a full technical datasheet (PDF) for a major supplier of citric acid (with full impurity limits, particle size, etc) and send you the link. Would that be helpful?
