CAS Number:
77-92-9
Chemical / IUPAC Name:
2-hydroxypropane-1,2,3-tricarboxylic acid
INCI Name:
Citric Acid
EC Number:
201-069-1 (for anhydrous form)
Molecular Formula:
C6H8O7
Molecular Weight:
192.12 g/mol
Other Names:
Anhydrous citric acid, 1,2,3-Propanetricarboxylic acid, 2-hydroxy-, 2-Hydroxy-1,2,3-propanetricarboxylic acid
Uses:
Citric acid anhydrous is a naturally occurring organic acid that appears as a white, crystalline, odorless powder with a strong acidic taste . As the anhydrous form contains no water molecules, it offers enhanced stability and is suitable for applications requiring precise moisture control . It is primarily produced through the fermentation of carbohydrate sources such as sugarcane, maize, or molasses .
· Cosmetics & Personal Care: Used in skincare and cosmetic products to adjust pH levels, enhance exfoliation, and support preservative systems . It is found in creams, gels, shampoos, and bath products, helping maintain formula stability and improving overall product performance .
· Pharmaceuticals: Serves as a pH modifier, effervescent component, and stabilizing agent in tablets, powders, syrups, and vitamin supplements . It is also used as an antioxidant excipient in pharmaceutical formulations .
· Food & Beverage Industry: Widely used as an acidulant, preservative, and flavor enhancer in soft drinks, confectionery, processed foods, sauces, and ready-to-drink formulations .
· Industrial Applications: Valued for its chelating strength in industrial and household cleaning products to remove limescale, rust, and mineral deposits . Also used in detergents, descalers, and dishwasher tablets as a safer alternative to harsher mineral acids .
· Laboratory & Research: Used in tissue culture systems, preparation of citrate buffers, and as a biochemical reagent .
Origin
Citric acid anhydrous is a naturally-derived or synthetically produced compound. Commercial production typically involves fermentation of carbohydrates (such as sugarcane, maize, or molasses) using specific strains of microorganisms (primarily Aspergillus niger), followed by purification and crystallization . It is a natural constituent of many fruits and vegetables, particularly citrus fruits.
What does Citric Acid Anhydrous do in a formulation?
- pH Adjuster / Buffer: Controls and maintains the acidity of formulations . pKa values are 3.13, 4.76, and 6.4 at 20°C .
- Chelating Agent: Binds to metal ions, preventing scaling and corrosion in industrial applications and stabilizing formulations in cosmetics .
- Antioxidant Synergist / Preservative: Helps prevent oxidation and spoilage, inhibiting microbial growth .
- Exfoliant: Provides mild chemical exfoliation (AHA) in skincare products at appropriate concentrations .
- Effervescent Agent: Reacts with bicarbonates in effervescent formulations to create rapid dissolution .
Safety Profile:
· General Hazard Classification: Classified with GHS hazard statements H319 (Causes serious eye irritation) . Signal word: Warning . Hazard Classifications: Eye Irrit. 2 - STOT SE 3 (Respiratory system) .
· GRAS Status: Generally Recognized as Safe (GRAS) by the FDA for use in food when used in normal quantities .
· Toxicity: Low acute toxicity. Oral LD50 (rat): 3,000 mg/kg .
· Irritation & Sensitization: Causes serious eye irritation . May cause mild skin irritation in sensitive individuals. Dust may cause respiratory tract irritation . Use of N95 dust mask, eyeshields, and gloves recommended when handling powder .
· First Aid (Eye Contact): IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses if present and easy to do. Continue rinsing. If eye irritation persists: Get medical advice/attention .
· Stability: Anhydrous form offers enhanced stability compared to monohydrate . In warm air, it may gradually lose water (effloresce); in humid air, it may be slightly hygroscopic .
· Storage: Store in a cool, dry place at 15-25°C . Protect from moisture and conditions of high humidity . Storage class: 11 - Combustible Solids .
· Shelf Life: Up to 5 years (1,825 days) when stored properly at temperatures below 30°C .
· Water Hazard Class: WGK 1 (slightly hazardous to water) .
· Regulatory Status: GRAS in the US. EU approved as food additive E330 . Meets USP , Ph.Eur. , and ACS specifications.
Technical profile:
| Property | Values |
| Appearance | Colorless, translucent crystals or white, granular to fine crystalline powder |
| Odor | Odorless |
| Assay (Purity) | 99.5 – 100.5% (USP/Ph.Eur. grade) ; ≥ 99.5% (ACS/Fisher BioReagents) ; ≥ 99% (synthesis grade) |
| Residue on Ignition | ≤ 0.02 – 0.1% |
| Water Content | ≤ 1.0% (anhydrous basis) . Typically 0.1% |
| Oxalic Acid | ≤ 360 ppm (0.036%) |
| Sulfates (SO?) | ≤ 150 ppm (0.015%) |
| Chloride (Cl) | ≤ 0.0025% (AR grade) |
| Heavy Metals (as Pb) | ≤ 10 ppm (0.001%) ; ≤ 5 ppm (AR grade) |
| Iron (Fe) | ≤ 0.001% (AR grade) |
| Bacterial Endotoxin | ≤ 2 EU/ml (USP grade) |
| pH (5% solution) | 1.7 (20°C, 50 g/L solution) ; 1.7 (100 g/L solution) |
| Melting Point | 153 – 159°C (with decomposition) |
| Boiling Point | 200°C at 1013 hPa (decomposition) |
| Density | 1.665 g/cm³ at 18°C ; 1.5 g/cm³ (approx.) |
| Bulk Density | 560 kg/m³ |
| Solubility | Very soluble in water (1330 g/L) ; Freely soluble in ethanol (96%) ; Very slightly soluble in ether |
| Vapor Pressure | < 0.1 hPa at 20°C |
| pKa | 3.13, 4.76, 6.4 (at 20°C) |
| Flash Point | Not applicable |
| Autoignition Temperature | 345°C |
| Explosive Limit | 8%, 65°F |
| Storage Temperature | 15-25°C (controlled room temperature) |
| Recommended Use Level | 0.1 – 5.0% in cosmetic and food formulations (varies by application). |