Lanthanum(III) Sulfate Hydrate: Properties, Handling & Lab Use

Lanthanum(III) Sulfate Hydrate is an inorganic rare-earth salt of trivalent lanthanum and sulfate, supplied as a crystalline hydrate and widely used as a reference reagent, precursor, and analytical standard in materials science, catalysis, and biological research.

Chemical Formula

La₂(SO₄)₃·nH₂O

CAS Number (anhydrous basis)

10099-60-2

Molar Mass (anhydrous)

566.00 g/mol

Appearance

White to off-white crystalline powder

Solubility in Water

Sparingly soluble; solubility decreases with increasing temperature (retrograde solubility)

Purity Grade

Typically ≥99% (trace metals basis); confirm Certificate of Analysis for lot-specific data

SKU

D304048

Chemical Identity and Physical Properties

Lanthanum(III) Sulfate Hydrate (La₂(SO₄)₃·nH₂O) is the hydrated form of lanthanum(III) sulfate, a white crystalline inorganic salt belonging to the rare-earth sulfate family. The lanthanum center carries a +3 oxidation state and coordinates with sulfate anions (SO₄²⁻) in a 2:3 ratio to maintain charge neutrality. Commercial hydrate forms commonly include the nonahydrate (n=9), though the exact degree of hydration should be confirmed from the supplier's Certificate of Analysis.

Key physical characteristics include a high melting point upon dehydration, relatively high density compared to organic salts, and a characteristic retrograde (inverse) aqueous solubility—meaning the compound becomes less soluble as temperature increases. This unusual property is important for dissolution protocols and crystallization experiments. The anhydrous molar mass is approximately 566.00 g/mol; for the nonahydrate form it is approximately 728.13 g/mol.

Purity, Grades, and Quality Specifications

Aladdin Scientific supplies Lanthanum(III) Sulfate Hydrate (SKU: D304048) at high purity suitable for research and analytical applications. Purity is typically reported as ≥99% on a trace-metals basis, with rare-earth impurities (e.g., cerium, praseodymium, neodymium) at the ppm level. Researchers requiring ultra-high-purity material for spectroscopic or radiological reference work should request the lot-specific Certificate of Analysis (CoA) to verify:

• Assay (% La₂(SO₄)₃ or % La)
• Water of crystallization (thermogravimetric or Karl Fischer)
• Heavy metal content
• Other rare-earth impurities

For stoichiometric calculations in solution preparation, always account for the hydrate water by using the lot-confirmed degree of hydration or by drying a weighed portion and correcting the mass accordingly.

Safe Handling, Storage, and Disposal

Personal Protective Equipment (PPE): Handle Lanthanum(III) Sulfate Hydrate wearing nitrile gloves, a laboratory coat, and safety goggles. Fine powders may cause respiratory irritation; work in a well-ventilated area or use a fume hood when weighing. An approved dust respirator (e.g., N95 or equivalent) is recommended when handling large quantities or during extended powder manipulation.

Storage: Store in a tightly sealed container in a cool, dry location away from incompatible materials (strong reducing agents, alkalis). The hydrate is hygroscopic under some humidity conditions; desiccated storage (silica gel desiccant) is recommended to maintain consistent hydration state and accurate weighing.

Disposal: Lanthanum-containing waste should be collected as inorganic heavy-metal waste and disposed of in accordance with local, national, and institutional regulations. Do not pour down the drain without consulting your institution's Environmental Health and Safety (EHS) office. Lanthanum ions can precipitate as hydroxides at neutral-to-alkaline pH and may interfere with wastewater treatment systems.

First Aid: In case of skin or eye contact, flush thoroughly with water for at least 15 minutes and seek medical attention if irritation persists. If inhaled, move to fresh air.

Dissolution Protocol and Solution Preparation

Due to its retrograde solubility, Lanthanum(III) Sulfate Hydrate dissolves more readily in cold water than in hot water. Follow these steps for reproducible solution preparation:

1. Determine effective molecular weight: Use the lot-confirmed degree of hydration. If the CoA indicates the nonahydrate (La₂(SO₄)₃·9H₂O, MW ≈ 728.13 g/mol), use this value for all stoichiometric calculations.
2. Weigh accurately: Tare the balance and quickly weigh the required mass into a pre-dried weighing boat. Minimize air exposure to limit moisture uptake variability.
3. Dissolve in cold deionized water: Add the powder gradually to cold (approximately 10–15 °C) high-purity deionized water (≥18 MΩ·cm) while stirring gently. Avoid heating; elevated temperatures will reduce solubility and may cause precipitation.
4. Adjust volume: Transfer quantitatively to a volumetric flask and make up to the final volume with cold deionized water.
5. pH adjustment (if required): Aqueous solutions of lanthanum sulfate are mildly acidic. Adjust pH carefully using dilute H₂SO₄ (to avoid introducing foreign anions) only if the application requires a specific pH.
6. Filtration: If turbidity is observed, filter through a 0.22 µm membrane filter before use.

Prepared solutions should be used promptly or stored at 2–8 °C to minimize hydrolysis and precipitation of lanthanum hydroxide over time.

Research Applications

Lanthanum(III) Sulfate Hydrate serves as a versatile reagent across multiple scientific disciplines:

• Materials Science and Ceramics: Used as a precursor for synthesizing lanthanum-doped oxides, lanthanum aluminate (LaAlO₃), and other perovskite-type materials with applications in solid oxide fuel cells (SOFCs), dielectrics, and catalytic supports.
• Catalysis: Lanthanum sulfate and derived lanthanum oxides act as promoters or active components in heterogeneous catalysts for dehydrogenation, oxidation, and steam-reforming reactions.
• Phosphor Research: Lanthanum compounds are host lattices for rare-earth luminescent centers; lanthanum sulfate hydrate serves as a soluble starting material for co-precipitation routes to phosphor precursors.
• Biological and Biochemical Research: La³⁺ ions are classical calcium channel blockers used in electrophysiology and cell biology to probe Ca²⁺-dependent processes. Lanthanum sulfate solutions provide a convenient source of La³⁺ for these studies.
• Analytical Chemistry: Serves as a releasing agent in flame atomic absorption spectrometry (FAAS) for elements such as calcium and phosphorus, suppressing interference from phosphate and aluminate matrices.
• Environmental and Geochemical Studies: Used as a reference compound for rare-earth element (REE) speciation, sorption, and fractionation experiments in soil and water research.

Frequently asked questions

What is the difference between the hydrate and anhydrous forms of lanthanum sulfate?

Lanthanum(III) Sulfate Hydrate contains bound water molecules in its crystal lattice (commonly as the nonahydrate, n=9), resulting in a higher molar mass than the anhydrous form (La₂(SO₄)₃). This must be accounted for in all stoichiometric calculations. The anhydrous form is obtained by heating the hydrate, but care must be taken because excessive heat can partially decompose the sulfate. Always confirm the degree of hydration from the lot-specific Certificate of Analysis before use.

Why does lanthanum sulfate become less soluble in hot water?

Lanthanum sulfate exhibits retrograde (inverse) solubility, a property shared by several inorganic sulfates where the dissolution process is exothermic. According to Le Chatelier's principle, increasing temperature shifts the equilibrium toward the solid phase, reducing solubility. This means solutions are best prepared in cold water (approximately 10–15 °C), and heating prepared solutions should be avoided to prevent precipitation.

Can lanthanum(III) sulfate be used to block calcium channels in cell biology experiments?

Yes. La³⁺ ions are well-established non-selective blockers of voltage-gated and ligand-gated calcium channels and are routinely used in electrophysiology and cell biology to inhibit Ca²⁺ influx. Lanthanum sulfate serves as a water-soluble source of La³⁺; however, researchers should note that La³⁺ also binds phosphate groups and can precipitate at physiological pH (≥7.4). Experimental buffers should be phosphate-free, and the working concentration and exposure time should be optimized for the specific cell type and assay.

How should I store Lanthanum(III) Sulfate Hydrate to prevent changes in hydration state?

Store the compound in a tightly sealed container with a desiccant (e.g., silica gel) in a cool, dry location at room temperature unless otherwise specified on the label. Avoid repeated opening in humid environments, as the hydrate can take up or lose water, altering the effective molar mass and introducing weighing errors in solution preparation.

What analytical technique is recommended for confirming purity of lanthanum sulfate?

Inductively coupled plasma optical emission spectrometry (ICP-OES) or ICP-mass spectrometry (ICP-MS) are the preferred methods for quantifying lanthanum content and detecting trace rare-earth and heavy-metal impurities at the ppm or ppb level. Thermogravimetric analysis (TGA) or Karl Fischer titration can confirm the degree of hydration. Refer to the lot-specific Certificate of Analysis from Aladdin Scientific for pre-confirmed purity data.

References

1. Lide, D. R. (Ed.). CRC Handbook of Chemistry and Physics, 97th Edition. CRC Press. (Solubility and physical property data for inorganic sulfates.)
2. Cotton, S. Lanthanide and Actinide Chemistry. Wiley, 2006. (General rare-earth coordination chemistry and properties.)
3. Weiss, G. B. Cellular pharmacology of lanthanum. Annual Review of Pharmacology, 1974, 14, 343–354. (La³⁺ as calcium channel blocker in biology.)
4. Greenwood, N. N.; Earnshaw, A. Chemistry of the Elements, 2nd Edition. Butterworth-Heinemann, 1997. (Rare-earth sulfate retrograde solubility and general inorganic chemistry.)

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.