What does sulphite mean?
A sulphite is a chemical salt or ion derived from sulfurous acid. Its characteristic ion is written SO₃²⁻, with one sulfur atom bonded to three oxygen atoms and carrying a charge of minus two. Sulphites occur in some foods and wines and may be added as preservatives because they help prevent oxidation and microbial spoilage. People with sensitivity to sulphites may therefore react to certain wines, dried fruit, or other preserved products. In general chemistry, the term distinguishes sulphites from sulfates, whose ion is SO₄²⁻, and from sulfides, which contain sulfur but no oxygen. The British spelling is “sulphite,” while “sulfite” is standard in American English. Outside food labelling and specialized chemical contexts, the word is chiefly encountered in technical writing.
nounA salt or ion derived from sulfurous acid, containing the sulfite ion (SO₃²⁻). In food labeling, sulphites refers broadly to sulfur dioxide and related compounds used as preservatives.
- A salt or ion derived from sulfurous acid and containing the sulfite ion, SO₃²⁻.
- A sulfur dioxide–related compound used to preserve foods and wines.
"The wine contains sulphites, which were added to prevent oxidation and preserve its freshness."
"The chemist measured the concentration of sulphite ions in the water sample."
"This wine is unsuitable for people sensitive to sulphites."
Used for individual sulphite compounds or, collectively in food labelling, for sulphite preservatives and related compounds.
"The manufacturer lists sulphites among the ingredients in the dried apricots."
Three oxygen atoms make a sulphite; add one more and it becomes a sulfate.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does sulphite come from?
The word was formed within the modern chemical naming system by combining the sulfur root with the suffix “-ite,” which denotes a salt or ion derived from a particular acid. “Sulphur” comes through English usage from Latin sulphur, while the English form “sulphite” also reflects the traditional British spelling of sulfur compounds. Related names in the same chemical family include “sulphuric” and “sulphate.”
How sulphite is actually used
The word is primarily technical, though it is also familiar from food-allergy information and wine labelling. “Sulphur dioxide” and “sulphites” are related but not interchangeable: sulphites are the salts or ions, while sulfur dioxide is the gas they can release in water.
Easily confused with sulphite
A sulfite contains the SO₃²⁻ ion, whereas a sulfate contains SO₄²⁻ and therefore has one more oxygen atom.
A sulfide contains sulfur without oxygen, while a sulfite is a sulfur-containing ion with three oxygen atoms.