Buyers in Muscat often find that one line on the invoice decides whether a magnesium sulphate shipment clears: the HS code. At the international 6-digit level, the magnesium sulphate HS code is 2833.21, "Sulphates, of magnesium". It sits in heading 28.33 of Chapter 28, Inorganic chemicals. The same code covers the anhydrous salt and the heptahydrate, in technical and pharmaceutical grades. For an oilfield or water lab, the harder choice is the grade, because the grade decides how the goods are described on your import papers and how they perform on the bench.
Magnesium Sulphate HS Code: 2833.21 Explained
Heading 28.33 covers sulphates, alums and peroxosulphates. Subheading 2833.21 is the 6-digit line for chemically produced magnesium sulphates. You will see it written as 283321 or 2833.21, or with national digits added, as 28332100. The water content does not change the code. Anhydrous MgSO4, dried powder and the heptahydrate MgSO4·7H2O (Epsom salt) all fall under HS code 2833.21.
Each country adds its own digits after the first six. The EU Combined Nomenclature and India use 28332100 (TARIC 2833.2100.00), Brazil's NCM uses 2833.21.00 and the US HTS uses 2833.21.00.00. The first six digits are the same everywhere.
When magnesium sulphate falls outside 2833.21
Two cases move the product to another heading. Check both before the goods ship:
- Natural minerals. Kieserite and epsomite that have not been chemically processed belong to heading 2530, not 2833. Published sources give 2530.20 and 2530.21 inconsistently, so confirm the current subheading in the tariff.
- Retail or measured-dose packs. Under Section VI Note 2, magnesium sulphate put up in measured doses or in retail packing for therapeutic or bath use can be classified under 3004 (medicaments) or 3307 (bath salts). Retail Epsom bath salts are commonly placed under 3307.30, and laxative or medicinal forms under 3004.90. Confirm both against the national tariff.
Reagent bottles for the lab and industrial bags for oilfield and water work are not put up for therapeutic or bath use, so they normally stay in 2833.21.
Importing into Oman: GCC 12-Digit Tariff and Clearance Documents
Oman uses the GCC integrated customs tariff, which extends the 6-digit HS code to 12 digits. For chemically produced magnesium sulphate the first six digits are 283321. Confirm the remaining national digits with Oman Customs or your clearing agent before the declaration is filed in Bayan, so the declaration matches the tariff in force.
Keep these papers consistent with each other:
- A commercial invoice that names the product in full, for example "magnesium sulphate heptahydrate, technical grade" or "magnesium sulphate anhydrous, laboratory grade", with the HS code.
- A certificate of analysis (CoA) for each batch, showing the assay and the grade standard (ACS, BP, USP or technical).
- The safety data sheet (SDS).
- A certificate of origin.
The grade wording matters. An invoice that combines "USP" or "BP" with "Epsom salt" can lead the officer to ask whether the goods are a medicament or a bath product. Using the chemical name, the CAS number 10034-99-8 for the heptahydrate and a stated end use such as laboratory or industrial supports classification under 2833.21.
Magnesium Sulphate Grades: Which One an Oilfield or Water Lab Should Buy
All grades share one HS code, but their specifications differ. Grades on the market include agricultural, feed, food, industrial or technical, reagent (ACS), pharmacopoeial (BP/USP/EP) and molecular biology. The material comes as heptahydrate crystals, dried powder or anhydrous powder.
- ACS reagent grade heptahydrate typically assays 98.0 to 102.0% by titration, with a typical pH (5% solution) of 5.0 to 8.2 and tight trace-metal limits. Labs use it to prepare magnesium standard solutions. A mud or water lab that runs hardness titrations should buy this grade.
- Pharmacopoeial grade (USP/BP/EP) heptahydrate typically assays 99.0 to 100.5% on the anhydrous basis. Buy it only when a client method or contract names a pharmacopoeia.
- Molecular biology grade typically assays ≥99.5% by complexometric titration, with heavy metals and iron each ≤5 ppm. Oilfield labs seldom need it.
- Industrial or technical grade heptahydrate typically contains about 48 to 49% MgSO4, 16% MgO, 9.6% Mg and 12% S. A 5% solution is near neutral, typically about pH 7, and the salt is fully water-soluble. This is the grade for wastewater, flocculation and bulk make-up work.
For bench work we list magnesium sulphate AR heptahydrate and a 500 g lab pack of magnesium sulphate. For water treatment work we list magnesium sulphate heptahydrate for treatment work. When you need the dry salt for water scavenging, contact us with your anhydrous grade requirements.
| Item | Detail |
|---|---|
| Our part numbers | RXSOL-19-1911-025 (Magnesium Sulphate); RXSOL-19-1911-050 (Magnesium Sulphate Heptahydrate); RXSOL-60-6179-500 (Magnesium Sulphate 500g); RXSOL-60-6604-892 (Magnesium Sulphate AR Heptahydrate) |
| HS code (6-digit) | 2833.21, Sulphates, of magnesium |
| Heptahydrate identity | CAS 10034-99-8, MgSO4·7H2O, molecular weight about 246.48 g/mol, colourless to white crystals |
| Typical heptahydrate specs (reagent and technical) | Assay ≥99.0%; pH of a 50 g/L solution typically 5.5 to 7.5; loss on drying typically 40 to 52%; chloride typically ≤0.03%; iron typically ≤20 ppm; heavy metals typically ≤10 ppm |
| Application | Laboratory reagent and drying agent, magnesium standard solutions, water scavenging in oil-based mud (anhydrous), flocculation and wastewater treatment |
| Packing | 500 g lab pack (RXSOL-60-6179-500) |
| Transport | Not regulated as dangerous goods (hazard class N/A) |
How Oilfield Labs Use Magnesium Sulphate
Hardness work on water-based mud and make-up water. Dissolved calcium and magnesium salts reduce the effectiveness of bentonite and polymers in drilling fluid and raise their consumption. The mud lab finds the magnesium ion by subtracting the calcium result from total hardness. Both values are titrated with standardised EDTA (versenate) using an ammonium hydroxide buffer, typically to API procedures. The endpoint changes from wine-red to blue. A reagent-grade magnesium standard prepared from ACS heptahydrate gives your lab a known reference for these titrations.
Water scavenging in oil-based mud. Anhydrous magnesium sulphate can be added to oil-based drilling fluid to scavenge water. A 50% excess over theoretical has been reported as effective. The reaction product is the heptahydrate, which has a low melting point, so it can distort free-water tests on treated mud. Your mud engineer should note the treatment on the report so the retort and free-water results are read correctly.
General lab use. Anhydrous grade also serves as a drying agent for organic extracts in the QC lab, and heptahydrate is used in microbiological media for water testing.
Storage and Packing for Muscat, Duqm and Sohar Sites
Magnesium sulphate heptahydrate is hygroscopic. On the coast at Muscat, Duqm and Sohar, open packs pick up moisture and cake, and shelf life suffers if packs are left open. Store it in a cool, dry, well-ventilated area with containers tightly closed, on pallets, protected from moisture and away from incompatible chemicals. Reseal lab jars immediately after use. On rig sites, keep bags off the floor of the mud store and away from wash-down areas.
Most safety data sheets report magnesium sulphate as not classified under GHS, with no signal word. At least one EU sheet carries a "Warning" signal word, so read the SDS from your supplier for your batch. Minimise dust, and use a P1-type dust mask where dust is generated. On strong heating it decomposes, releasing sulphur oxides and magnesium oxide.
Choose the pack to suit the job. A 500 g lab pack suits a QC bench in Nizwa or a mud lab at the rig. For larger quantities, contact us with your grade and quantity.
Where to Buy Magnesium Sulphate in Muscat and Oman
Oman Chem (Muscat & Barka for Business Trading), Barka Industrial Area, Sultanate of Oman. Phone +968 77333599, WhatsApp +968 77333599, email muscatchem@gmail.com. The same 500 g pack is also listed on our sister sites: Sohar Chemical listing and Muscat Chemical listing. Send your grade, quantity and site on our quote request page.
Frequently Asked Questions
What is the HS code for magnesium sulphate?
At the 6-digit level it is 2833.21, "Sulphates, of magnesium", in heading 28.33 of Chapter 28. Countries add national digits after these six.
Is Epsom salt under the same HS code as anhydrous magnesium sulphate?
Yes. HS 2833.21 covers both, whatever the water content. The exception is magnesium sulphate put up in retail or measured-dose packs for bath or therapeutic use, which can move to 3307 or 3004.
What is the 12-digit GCC customs code for magnesium sulphate in Oman?
The first six digits are 283321. Oman uses the GCC integrated tariff, so confirm the full 12-digit national code with Oman Customs or your clearing agent before you file the declaration.
Which grade should an oilfield or water lab buy?
Buy ACS reagent or AR grade heptahydrate for standard solutions and hardness work, anhydrous grade for water scavenging in oil-based mud, and technical grade for bulk treatment use.
Is magnesium sulphate hazardous for transport?
No. It is not regulated as dangerous goods for transport. Most SDS do not classify it under GHS, but always check the SDS for your batch.
Request a quote for magnesium sulphate in the grade and pack your lab needs: message us on WhatsApp at +968 77333599.
Frequently asked questions
What is the HS code for magnesium sulphate?
At the 6-digit level it is 2833.21, "Sulphates, of magnesium", in heading 28.33 of Chapter 28. Countries add national digits after these six.
Is Epsom salt under the same HS code as anhydrous magnesium sulphate?
Yes. HS 2833.21 covers both, whatever the water content. The exception is magnesium sulphate put up in retail or measured-dose packs for bath or therapeutic use, which can move to 3307 or 3004.
What is the 12-digit GCC customs code for magnesium sulphate in Oman?
The first six digits are 283321. Oman uses the GCC integrated tariff, so confirm the full 12-digit national code with Oman Customs or your clearing agent before you file the declaration.
Which grade should an oilfield or water lab buy?
Buy ACS reagent or AR grade heptahydrate for standard solutions and hardness work, anhydrous grade for water scavenging in oil-based mud, and technical grade for bulk treatment use.
Is magnesium sulphate hazardous for transport?
No. It is not regulated as dangerous goods for transport. Most SDS do not classify it under GHS, but always check the SDS for your batch.
