Sodium Dihydrogen Citrate: Description and Detailed Physical Properties

What is Sodium Dihydrogen Citrate?

Sodium dihydrogen citrate has built its reputation as a versatile chemical raw material, widely accepted in both industrial and laboratory settings for its distinct properties. The compound stands out with its white crystalline form, often seen as solid powder, flakes, or pearls, according to specific handling needs. Its formula, NaC6H7O7, draws attention due to a unique structure combining sodium with the citric acid backbone, offering a balance between moderate reaction and strong acidity regulation. The density averages at roughly 1.7 grams per cubic centimeter, creating a stable, easily measured solid that holds up well during storage and shipping. Those working in quality control or dealing with specifications will spot the HS Code 2918150000, linking distribution to standardized documentation.

Key Physical and Chemical Features

Experts appreciate sodium dihydrogen citrate for its solubility in water, forming a clear, colorless solution readily without the need for special conditions. Commercial lots tend to focus on purity above 98%, minimizing unpredictable reactions. The substance melts above 150°C without charring, marking it as thermally stable until decomposition, which matters for manufacturing reliability. Crystals often grow as orthorhombic, adding predictability to both laboratory and bulk processes. The material holds a mildly acidic pH, usually between 3.5 and 4.5 in standard 0.1M solutions, making it an effective regulator in beverages, pharmaceuticals, and medical diagnostics. The powder, though solid at room temperature, easily absorbs moisture, so manufacturers invest in tight packaging and low-humidity storage to keep samples dry and clumping-free.

Structure and Molecular Information

The sodium dihydrogen citrate molecule consists of a central citrate anion (C6H7O7-) with a single sodium ion balancing one of the acid groups, while two carboxyls remain protonated. This hybrid composition introduces selective buffering action in solution, unlike full sodium or potassium citrate variants. Chemists working with the material often reference its molar mass of 214.11 g/mol, which helps calculate quantities for reactions and solutions. Structural analysts see a clear distribution of six carbon atoms forming a three-armed citric skeleton, with attached hydroxyl and carboxylate groups responsible for the substance’s mild acidity and stable chelating behavior. The molecular orientation supports effective ion exchange in water, which influences solubility and the tendency for the raw material to disperse without residue.

Appearance, Forms, and Material Handling

Most users encounter sodium dihydrogen citrate as a white to colorless powder with almost no odor, which avoids the risk of cross-flavor in food and beverage applications. Flakes or pearls appear during large-scale industrial crystallization, where batch handling and air circulation matter more than appearance. In rare research cases, the substance also turns up in a liquid format, as a concentrated solution for direct dosing or buffer preparation. Bulk density ranges between 700 and 900 kg/m³ depending on powder granulation, which affects storage, transport, and the calibration of dosing equipment. Whether stored as a dry solid or liquid, the material fares best in sealed, air-tight containers and away from heat to prevent decomposition or caking. Efficient production lines rely on high-flow, non-caking powders to guarantee both manual and automated dispensing, supporting accuracy in everything from pharmaceuticals to food processing.

Safety, Hazardous Nature, and Handling Practices

Sodium dihydrogen citrate generally stands out for its low toxicity and good biodegradability, giving it a favorable profile compared to many chemical additives or acidulants. Direct contact with eyes or mucous membranes might cause mild irritation, but extensive animal studies show no evidence of carcinogenic or mutagenic effects. That said, workers handling bulk quantities of the powder often use gloves and eye protection, as standard practice for fine chemicals that can become airborne. Regulatory agencies have not categorized the compound as hazardous for normal transport or use, but manufacturers warn against mixing it with strong oxidizers, reducing agents, or exposure to extreme heat, which could drive unexpected side reactions or rapid decomposition. Material Safety Data Sheets instruct quick rinsing with water for accidental exposure and recommend mechanical ventilation for larger operations, ensuring air quality stays well below nuisance dust thresholds.

Uses and Industry Role

Food and beverage industries increasingly prefer sodium dihydrogen citrate as a safe acidulant and buffer, especially in products demanding clean, tart notes without unwanted metallic aftertaste. Pharmaceutical producers draw on its buffering action to stabilize formulations or control pH in sensitive syrups, tablets, and injectables. In laboratory science, this chemical underpins precise pH calibration, enzyme stabilization, and gentle chelation for biologically active samples. Water treatment plants sometimes deploy it to modulate mineral balance, helping prevent scaling and corrosion. Each field synthesizes its standards but all focus on reproducibility, purity, and traceability from batch to batch.

Addressing Supply and Quality Challenges

Ensuring reliable access to sodium dihydrogen citrate demands attention to both international supply chains and periodic review of sourcing practices. When manufacturers prioritize consistent particle size and low impurity levels such as heavy metals or insoluble residues, the result is fewer production errors and reduced risk to end users. Industry watchdogs often cite the need for regular re-certification and testing, especially as more countries introduce stringent food and pharmaceutical regulations. Investing in detailed specification sheets, traceable batch records, and third-party lab verification helps both buyers and sellers align quality expectations. As global demand climbs, it pays to monitor shifts in raw material pricing that cycle through lemon and other agricultural feedstocks, which ultimately set the efficiency limits for citric acid derivatives like sodium dihydrogen citrate.