CAS 1309-48-4 is the registry number for magnesium oxide. It tells a customs officer or a safety officer which substance is in the drum, and nothing more. Two shipments carrying the same CAS number can behave very differently in a formulation, because the number says nothing about assay, bulk density, particle size, activity or heavy metals.
The standards that matter in China
Industrial magnesium oxide is commonly specified against HG/T 2573-2012, the chemical industry standard for industrial magnesium oxide. Zehui Magnesium was one of the drafting units for that standard, so the grade tables we publish are written against the same test methods our own laboratory uses for batch release.
Food-grade magnesium oxide is a different conversation: it is specified against GB 1886.217-2016 and judged on heavy metals, arsenic, lead and loss on ignition as much as on assay. Pharmaceutical and reagent grades add their own pharmacopoeial or analytical-reagent requirements.
What to put on the purchase order
- The grade code, not just the chemistry — for example ZH-V2 for 99.7% minimum high-purity MgO for electronic ceramics.
- The controlling standard and the revision you require.
- The parameters you will actually test on receipt: assay, acid-insolubles, chloride, bulk density and particle size.
- Whether you need a batch certificate of analysis, and whether a third-party inspector will be nominated.
Why we publish measured values only
Our grade tables separate measured typical values from contractual limits. Where a value is grade-specific rather than generic, we mark it "on request" and issue the figure with the technical data sheet for that grade. We do not fill a parameter with an industry-average number that nobody has measured on your batch.
Need the measured values for a specific grade? Ask our technical team for the data sheet and a trial sample.