Sodium gluconate starts life as glucose, a sugar from plant starch. Fermentation usually turns the glucose into gluconic acid (a mold or bacterium does the work), and a sodium base turns that into the salt we use. Its job is unglamorous and important: grab the calcium and iron in hard water so they are less likely to settle onto your laundry as the film that makes clothes look dull.
Quick facts
- What it is: the sodium salt of gluconic acid, a white crystalline powder
- Its job in our products: chelating agent (binds hard-water minerals)
- Where it comes from: fermented from plant-derived glucose
- EPA Safer Choice: green circle
- EPA TSCA review: its parent acid, D-gluconic acid, was designated low-priority in 2020 (explained below)
- EWG grade: B (see the EWG page)
- CAS number: 527-07-1
Built for an alkaline wash
Gluconate binds calcium and iron ions and holds them in solution. Chemists call this chelation. In the wash, those minerals are then less able to interfere with the cleaning ingredients and less likely to settle back onto fabric. It is widely used as a chelating agent in household and industrial cleaners, including alkaline ones, and a 2002 lab study measured gluconate holding iron, and iron and calcium together, in alkaline solution. That is why it suits the alkaline wash our laundry powders create.
One of three mineral helpers
In Max Strength Laundry Powder it shares the work with sodium citrate, which holds calcium and magnesium in solution, and sodium polyaspartate, which slows the growth of mineral scale. Gluconate binds iron as well as calcium. How much difference you see depends on the formula and your water hardness.
What EPA's 2020 review says
In 2020, EPA designated D-gluconic acid a low-priority substance under the Toxic Substances Control Act, meaning it does not need a full risk evaluation for now. EPA is clear that this is not a finding of no risk. Much of the review rests on data for sodium gluconate: it broke down by more than 60 percent in 10 days in a standard OECD test, so it is readily biodegradable, and it is expected to break down completely without oxygen within 35 days. Fish and water fleas showed no adverse effects at the highest concentrations tested.
EPA also lists sodium gluconate with a green circle, and EWG gives it a B; follow the link for EWG's reasoning. Neither rating is for our finished products (see how we vet ingredients).
Handling and safety
Sodium gluconate dust can irritate the eyes. Once it is in the wash, it is diluted and goes down the drain with the rinse water. Use as directed and avoid contact with eyes. If any gets in eyes, rinse cautiously with water for several minutes. If any is swallowed, call Poison Control at 1-800-222-1222. Store powders sealed in their pouch, up high or in a latched cabinet, out of reach of children and pets.
Where you'll find it
- Laundry: Fragrance-Free Laundry Detergent (60 loads), EWG Verified Max Strength Laundry Powder
- Kits and bundles: Ultimate Home Bulk Bundle, Expert Home Cleaner Kit, Complete Surface Cleaner Starter Kit
All are fragrance-free except the Expert Home Cleaner Kit and the Complete Surface Cleaner Starter Kit, which include scented sprays. Each product page has the full ingredient list.
Sources
- America's Poison Centers. (n.d.). Poison Help. https://poisoncenters.org/
- Bechtold, T., Burtscher, E., & Turcanu, A. (2002). Ca2+-Fe3+-D-gluconate complexes in alkaline solution: Complex stabilities and electrochemical properties. Journal of the Chemical Society, Dalton Transactions, (13), 2683-2688. https://doi.org/10.1039/B202086F
- Environmental Working Group. (n.d.). EWG's Guide to Healthy Cleaning: Sodium gluconate. https://www.ewg.org/cleaners/substances/5563-SODIUMGLUCONATE/
- National Center for Biotechnology Information. (n.d.). PubChem compound summary: Sodium gluconate. https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-gluconate
- U.S. Environmental Protection Agency. (2020). Supporting information for low-priority substance D-gluconic acid (CASRN 526-95-4): Final designation. https://www.epa.gov/sites/default/files/2019-08/documents/support_document_for_proposed_designation_of_d-gluconic_acid.pdf
- U.S. Environmental Protection Agency. (n.d.). Safer Choice: Safer Chemical Ingredients List. https://www.epa.gov/saferchoice/safer-ingredients
