Short answer. Isopropyl alcohol strength is stated by weight (w/w) or by volume (v/v), and the two are not interchangeable. About 70% v/v is the common disinfection strength, while 99% and above is used for solvent duties. Dilute with C1 x V1 = C2 x V2, and note that SPC supplies Technical (99.80% w/w min) and IP (99.0% v/v min) only, not ready-diluted 70%.
Why IPA strength is a units question first
Isopropyl alcohol (isopropanol, 2-propanol, CAS 67-63-0) mixes with water in all proportions, so strength is a choice rather than a fixed property. Most mistakes come from units, not chemistry: a percentage can be weight by weight, volume by volume or a density reading, and drum orders are placed in litres while tankers are traded in tonnes. This guide is general knowledge to help you read a strength correctly, dilute with confidence and convert an order quantity; the specification for what SPC supplies is on the isopropyl alcohol (IPA) product page.
For which industries use which strength and grade, see the IPA grades and uses guide. In short, about 70% v/v is commonly used for disinfection and 99% and above for solvent duties such as inks, coatings, electronics cleaning and extraction. Follow your own regulatory or infection-control team for any claim on a finished product.
Weight, volume and density: the w/w and v/v trap
Concentration can be stated as percent weight by weight (w/w), percent volume by volume (v/v), or sometimes by density. They are not the same number. Because isopropyl alcohol is lighter than water, a mixture that is 70% by volume contains a smaller share by weight. As a rough guide, 70% v/v is a little over 60% w/w; do not rely on that approximation for a specification, use a density table or your lab.
This matters when you compare grades. SPC's Technical grade is stated as 99.80% w/w minimum by GC, while IP grade is stated as 99.0% v/v minimum. The two figures are on different bases, so a 99.80 beside a 99.0 does not mean Technical grade is purer in any simple sense. Read the basis printed on the data sheet and on the batch Certificate of Analysis. Our guide to reading an IPA Certificate of Analysis walks through each line.
How do I dilute IPA to 70%? A worked example
To make a weaker IPA from a stronger one, use the dilution relation C1 x V1 = C2 x V2, where C is concentration and V is volume. Say you need 1 litre of 70% v/v IPA from 99.0% v/v IPA (the IP-grade minimum):
- V1 = (70 x 1000 ml) / 99.0 = about 707 ml of IPA.
- Add water until the total reaches 1000 ml (about 293 ml, but see below).
Two practical points. First, alcohol and water shrink slightly on mixing, so measure the IPA first, then add water up to the 1 litre mark rather than adding exactly 293 ml. Second, scale up the same ratio for larger batches: for 1000 litres of 70% v/v, start from about 707 litres of 99.0% v/v IPA. If your starting figure is a w/w assay, as on the Technical grade, convert it to a volume basis first or ask your lab to confirm the final strength by density.
Diluted IPA is still flammable. Dilution lowers the risk but does not remove it, so keep the SDS requirements for ignition control in force. Making sanitisers or disinfectants for sale is also a regulated activity; confirm the licences and standards that apply to your finished product before you start.
Litres, kilograms and tonnes: avoiding order mistakes
IPA is traded in litres in drums and IBCs and in tonnes in bulk tankers, so mixing the two units is a common source of short or over-ordered consignments. The Technical-grade data sheet density ranges run from 0.783 to 0.787 depending on the maker and temperature (specific gravity at 25 C from one maker, relative density at 20 C from the other). The table below uses that range. These are planning figures; the invoice weight and Certificate of Analysis govern.
| Container or quantity | Approximate mass |
|---|---|
| 200 L barrel | about 156.6 to 157.4 kg |
| 1000 L IBC | about 783 to 787 kg |
| 1 tonne (1000 kg) | about 1,271 to 1,277 L |
Source: general knowledge arithmetic using the TDS density range (0.783 to 0.787); planning figures only, not an SPC specification.
When you enquire, say which unit your quantity is in, and whether it is a per-batch or a monthly figure. That avoids a rework of the quote.
Which IPA grades does SPC supply?
Supreme Petro Chemicals is a Chennai importer and bulk distributor of chemicals for ink, coating, electronics, pharma, cosmetics and sanitiser manufacturers. SPC lists two concentrated IPA grades:
| Grade | Assay | Water | TDS |
|---|---|---|---|
| Technical | 99.80% w/w minimum (GC) | 0.10% w/w maximum | SPC-TDS-ALC-001 |
| IP (Indian Pharmacopoeia) | 99.0% v/v minimum | 0.50% maximum | SPC-TDS-ALC-006 |
Source: SPC TDS SPC-TDS-ALC-001 and SPC-TDS-ALC-006.
Technical grade is not a pharmacopoeial, food or pharma grade; if your process is pharmaceutical, ask for IP grade and have your QA team approve the batch Certificate of Analysis. Those two are the only IPA grades SPC lists, so ready-diluted 70% IPA is not part of the range. BP limits are close to IP and can be discussed on request. The IP, BP and USP explainer covers how pharmacopoeial grades differ.
A short checklist before you order or dilute
- Is the process water-sensitive? If yes, start from a concentrated grade and avoid diluting on site.
- Is the end use regulated? If it touches a pharma process, choose IP grade and let QA decide.
- Will you dilute? Use the dilution method above, and verify the final strength by density.
- Which unit? Convert litres and kilograms before you place the enquiry.
Get a quote
Send the grade, quantity (with the unit), pack and delivery location by call or WhatsApp on +91 86087 80096. We quote within 4 working hours, and a batch Certificate of Analysis is supplied with every delivery. Buyers in Chennai can also see our IPA supply page for Chennai.