CA6940 Calcium Citrate Anhydrous Powder

Calcium Citrate Anhydrous Powder Description

Calcium Citrate Anhydrous Powder (Ca₃(C₆H₅O₇)₂, molecular weight 498.44 g/mol) is a white, odourless, crystalline powder that contains no water of crystallisation. Its anhydrous state ensures high chemical purity and improved stability compared to hydrated forms. The compound is highly soluble in water, forming slightly turbid solutions because of trace amounts of calcium hydroxide. It remains insoluble in ethanol and most organic solvents. Thermal decomposition occurs when heated beyond approximately 120°C, thereby removing any residual moisture.

This compound exhibits pH-independent solubility across acidic and neutral environments. Calcium ions are released consistently even when gastric acid levels are low. The citrate anion functions as a chelating agent, thereby assisting calcium absorption in the intestines without affecting iron uptake. Elementally, the powder contains approximately 21% bioaccessible calcium by weight.

The compound crystallises in a triclinic crystal system with coordination bonds between calcium ions and citrate carboxylate groups. It is identified by CAS registry 813-94-5 and specific spectroscopic markers, for example, IR absorption for carboxylate groups at approximately 1 600 cm⁻¹. Its dissolution kinetics are consistent and its stability is maintained under ambient humidity due to the absence of water.

Calcium Citrate Anhydrous Powder Applications

Dietary Supplements: The powder is used as a calcium source with 21% elemental Ca. It is suitable for individuals with reduced gastric acid, such as older persons or those on acid-reducing medications, because absorption is independent of pH. In contrast to calcium carbonate, it may be administered without food.

Food Fortification: The compound is used to fortify products including plant-based milks, juices, cereals and baked goods with calcium. Its neutral taste, solubility and stability during processing are maintained.

Pharmaceuticals: The powder is utilised as a tablet binder/disintegrant and as a source of calcium ions in antacids, medications for osteoporosis and chewable tablets. It is non-hygroscopic and meets defined purity criteria.

Industrial Functions: The compound is employed as a chelating agent in cleaning products to bind metal ions. It also functions as a buffer and pH stabiliser in cosmetics and chemical processes.

Medical Nutrition: The powder is incorporated into clinical nutrition formulas, such as tube-feeding solutions, where rapid calcium absorption and solubility are required.

Calcium Citrate Anhydrous Powder Packaging

Products are packaged in customised cartons of various sizes based on material dimensions. Smaller items are enclosed in PP boxes, while larger items are packed in custom wooden crates. Appropriate cushioning materials are used during transportation to protect the goods.

Packaging: Carton, Wooden Box, or Customized.

Kindly review the packaging details provided for your reference.

Manufacturing Process

1.       Testing Method

(1)    Chemical Composition Analysis was performed using GDMS or XRF. This verified purity compliance.

(2)    Mechanical Properties Testing included measurements of tensile strength, yield strength and elongation. This assessed material performance.

(3)    Dimensional Inspection measured thickness, width and length. This ensured that specified tolerances were met.

(4)    Surface Quality Inspection was carried out using visual and ultrasonic examination to detect defects such as scratches, cracks or inclusions.

(5)    Hardness Testing determined material hardness and confirmed uniformity and mechanical reliability.

Please refer to the Stanford Advanced Materials (SAM) testing procedures for further details.

Calcium Citrate Anhydrous Powder FAQs

Q1. What are the advantages of this form over calcium carbonate?

The powder achieves a bioavailability rate of 35–40% regardless of gastric acid levels. Calcium carbonate requires an acidic environment and generally achieves 10–20% absorption. It may be taken on an empty stomach and does not interfere with non-heme iron absorption.

Q2. Which populations derive particular benefit from this calcium source?

The compound is indicated for individuals aged 50 years or older experiencing reduced gastric acid production. It is appropriate for patients on long-term acid-reducing medications, for persons with gastrointestinal sensitivity due to a lower incidence of constipation in comparison to carbonate salts, and for lactose-intolerant or vegan individuals requiring a non-dairy calcium source.

Q3. What are the dosing parameters and safety considerations?

The tolerable upper intake level for elemental calcium is 2 000 mg per day from combined sources. Individual doses should not exceed 500 mg elemental calcium to ensure optimal absorption. Excessive chronic intake may increase the risk of nephrolithiasis and vascular calcification.

Related Information

1.       Common Preparation Methods

Calcium Citrate Anhydrous Powder is synthesised via a controlled neutralisation reaction between citric acid and a calcium base, either food-grade calcium hydroxide or calcium carbonate. Citric acid is dissolved in deionised water with agitation at 70–80°C. The calcium source is added gradually while maintaining a stoichiometric ratio of 2:3 (citric acid to calcium). The reaction produces calcium citrate tetrahydrate as an intermediate precipitate. The slurry is crystallised at a pH of 5.0–6.0 for 1–2 hours. Hydrated crystals are then separated by centrifugation or filtration and washed with deionised water to remove chloride and sulphate impurities. Dehydration is achieved by thermal treatment in forced-air dryers at 110–120°C for 4–6 hours, thereby eliminating water of crystallisation without causing decomposition above 160°C. Milling yields a fine powder with a particle size distribution of 20–150 μm. Final purification may involve recrystallisation from ethanol–water mixtures to reduce residual citrate or unreacted calcium, achieving pharmaceutical-grade purity exceeding 99.5%. Quality verification is performed using X-ray diffraction, loss-on-drying testing (<1.0% moisture) and atomic absorption spectroscopy, which confirms a calcium content between 20.5% and 21.5% w/w.