"A practical supplier guide to L-Ascorbic Acid (CAS 50-81-7, C6H8O6, MW 176.12): the biologically active form of vitamin C, supplied as a white to faintly yellow crystalline powder with a melting point of 190-194 C (dec.), water solubility of 50 mg/mL at 20 C, density 1.65, and EINECS 200-066-2. Covers its three cosmetic jobs (antioxidant, tyrosinase-inhibiting brightening, collagen support), its food and beverage use as an antioxidant and nutrient, and its pharmaceutical and analytical roles. Includes stability, grade, and handling notes, and compares it with kojic acid, alpha-arbutin, glabridin, citric acid, tartaric acid, and chlorogenic acid."
-Deshangchemical-chemechemi
What L-Ascorbic Acid Actually Is
L-Ascorbic Acid (CAS 50-81-7) is the form of vitamin C that the human body recognizes and uses. Chemically it is C6H8O6, with a molecular weight of 176.12, and it carries the EINECS number 200-066-2. Most buyers meet it as a white to faintly yellowish crystalline powder, though on long storage or under poor conditions it can darken — a practical signal that oxidation has set in rather than a defect in the molecule itself. It is the reference point every other “vitamin C” derivative is measured against, because no ester or salt matches its direct biological and antioxidant activity gram for gram.
The Numbers You Spec Against
On the data sheet the figures that matter for handling are straightforward. The melting point is 190–194 °C with decomposition, which already tells you this is not a material you melt and pour. Solubility in water is about 50 mg/mL at 20 °C — it goes into solution readily, but the solution is where the trouble starts, because ascorbic acid is a reducing agent that gives up electrons willingly. Density is around 1.65 g/cm³, and we recommend storage between +5 °C and +30 °C, dry and away from light. The real enemies in a warehouse are oxygen, heat, and trace metal ions; keep those out and the assay holds.
Why Cosmetic Formulators Keep Coming Back to It
In skin care, L-ascorbic acid earns its place on three jobs. First, it is a genuine antioxidant — it scavenges free radicals generated by UV and pollution, which is why it shows up in serums meant to be worn under sunscreen rather than instead of it. Second, it interferes with tyrosinase, the enzyme that builds melanin, so it is used in brightening formulas aimed at uneven tone and post-acne marks. Third, it is one of the few topical actives with a documented role in supporting collagen synthesis, which keeps it in the anti-aging conversation alongside peptides.
The catch is stability. In water it oxidizes, and on the skin its activity window is narrow unless the formula is held acidic, typically around pH 3.0–3.5. That is why finished products lean on opaque, air-restricted packaging and why formulators often compare it against gentler, more stable brightening actives. When the brief calls for tyrosinase inhibition without the pH and oxidation headaches, kojic acid (CAS 501-30-4) is the classic alternative, and alpha-arbutin (CAS 84380-01-8) is the go-to for a water-stable, lower-irritation brightener. For plant-derived tone correction, glabridin (CAS 59870-68-7) from licorice root is another name that comes up in the same formulation meeting.
The Food and Beverage Side of the Same Drum
Outside the cosmetic lab, the largest steady demand is from food and beverage producers, where L-ascorbic acid is used as an antioxidant and nutrient additive. It slows browning and off-flavor development in fruit preparations, jams, and beverages, and it is the vitamin itself when a product is being fortified. This is a different buying conversation from cosmetics — here the comparison set is other food-grade acids used for acidification and shelf-life, not brightening. Citric acid anhydrous (CAS 77-92-9) and D-tartaric acid (CAS 147-71-7) sit in the same specification folders as acidulants and synergists, and chlorogenic acid (CAS 327-97-9) is the natural-extract antioxidant buyers reach for when they want a plant-source claim alongside the synthetic vitamin.
Pharmaceutical and Analytical Uses
In pharma it is the active vitamin drug used to prevent and treat scurvy and to correct deficiency, and it is listed in many pharmacopeias. It also has a long life as a reagent: a standard reducing agent, a masking agent for metal ions in titrations, and a chromatography and analytical reference. For buyers in this channel the paperwork — monograph compliance, heavy metals, residual solvents — matters as much as the price, and the grade is not interchangeable with the cosmetic or food grade.
What Separates One Lot From Another
Because the CAS number is identical for every supplier, the things that actually differentiate a lot are assay consistency, low color, a clean heavy-metals panel, and how the material was packed and stored before it reached you. Ascorbic acid that has been exposed to heat or humidity arrives darker and assays lower, and you only find that out after it is in your line. We ship against a current certificate of analysis, can document assay, heavy metals, and loss on drying on request, and pack in polyethylene-lined fibre drums or foil bags sized to your batch.
Handling Notes Worth Passing to the Floor
It is low hazard but oxidizes easily, so keep containers tightly closed, store cool and dry, and avoid contact with copper or iron surfaces and strong oxidizers. Once a solution is made up, use it the same day or protect it from air; a faint yellow tint in solution is the first visible sign it is already losing potency. Gloves and eye protection are sensible for anyone handling the powder in volume.
Where to Go From Here
L-ascorbic acid is about as established as an ingredient gets, but it is unforgiving on storage and formulation, and the right grade depends entirely on whether it is going into a serum, a beverage, or a tablet. If you are scoping a formulation or a fortification program and want to talk through grade, particle size, and lead time, the product page carries the current specification, and we are happy to send a sample for bench and sensory testing before you commit to a full order.
