IPA Isopropyl Alcohol

Identification of IPA Isopropyl Alcohol (propan-2-ol, CAS 67-63-0, UN 1219) as a process solvent begins with ASTM D770-21, which defines commercial isopropyl alcohol grades through assay, water, acidity, and nonvolatile residue controls. The product line is configured as IPA-99.8-200L, IPA-99.5-1000L, and IPA-70-USP-20L; the numerical prefix indicates minimum assay or nominal aqueous concentration, and the suffix is the standard pack size in litres. At 20 °C, density is 0.785 g/cm³, vapour pressure is 4.4 kPa, and the closed-cup flash point is 12 °C. The autoignition temperature is 399 °C. Production-scale transfer lines are specified in 316L stainless steel with conductive PTFE gaskets because the solvent is a low-conductivity liquid and static charge can accumulate during drum-to-tote dispensing above 60 L/min. Zone classification for the dispensing area is performed according to IEC 60079-10-1 when vapour concentrations exceed 2.0 vol% lower explosive limit.

The incoming QC release limits are consolidated in the following specification table. Values are lot-release maxima or minima unless noted; the electronic grade carries additional trace-metal and filtration controls that are reported on the certificate of analysis.

Parameter	Test method	IPA-99.8-200L	IPA-99.5-1000L	IPA-70-USP-20L
Assay	GC-FID	>99.8 wt%	>99.5 wt%	68.0–72.0% v/v
Water	Karl Fischer titration	≤0.10 wt%	≤0.20 wt%	remainder
Nonvolatile residue	ASTM D1353	≤0.001 g/100 mL	≤0.002 g/100 mL	≤0.005 g/100 mL
Acidity as acetic acid	titration	≤0.002 wt%	≤0.002 wt%	≤0.002 wt%
Colour	ASTM D1209	≤10 Pt-Co	≤10 Pt-Co	not specified
Distillation range	ASTM D1078	81.0–83.0 °C	81.0–83.0 °C	not specified
Particle count ≥0.5 µm	light obscuration	≤100 particles/mL	not specified	not specified
Sodium, potassium, iron, nickel, copper	ICP-MS	<10 ppb each	<100 ppb each	not specified

Each release lot is filtered for the electronic grade through 0.2 µm polytetrafluoroethylene membranes. Trace-metal limits are not a substitute for end-use contamination testing in semiconductor cleaning because packaging headspace can transfer boron and siloxanes to the wafer surface after opening.

What Distinguishes 99.8 wt% Electronic-Grade IPA from 70.0% v/v Isopropyl Rubbing Alcohol?

Water content governs both evaporation profile and solvency. The 70.0% v/v aqueous preparation is held within 68.0–72.0% v/v because the water fraction reduces vapour pressure and prolongs contact time on wetted surfaces; the anhydrous 99.8 wt% grade is selected when residual water interferes with polyurethane cure or electronic component assembly. At atmospheric pressure, IPA-water forms a minimum-boiling azeotrope at 80.4 °C and 87.7 wt% IPA. Simple batch distillation of a 70% v/v feed therefore cannot yield anhydrous IPA; the enriched overhead remains near the azeotropic composition, and the remaining water is removed by azeotropic dehydration or molecular sieve polishing. In pharmaceutical compounding, the aqueous grade is used as a topical antiseptic solvent, not as a terminal sterilant. EN 1040 and EN 1276 test data on the final formulated product, rather than the USP monograph for isopropyl rubbing alcohol alone, establish bactericidal activity. Published data for sporicidal activity of IPA in this product configuration is limited; the solvent is not classified as a high-level disinfectant. Substitution of anhydrous for aqueous IPA in an enclosed wipe converting cell raised vapour concentration above 2.0 vol% lower explosive limit and initiated LEL sensor shutdown; the upper explosive limit is 12.7 vol%.

During substitution trials on polycarbonate lens-carrier plates, IPA exhibited slower removal of acrylate-based pressure-sensitive adhesive residues than acetone. The measured Hansen solubility parameters for IPA are δD=15.8 MPa^0.5, δP=6.1 MPa^0.5, δH=16.4 MPa^0.5; acetone has δD=15.5 MPa^0.5, δP=10.4 MPa^0.5, δH=7.0 MPa^0.5. The lower polar parameter reduces the rate of bisphenol A polycarbonate surface etching but also lowers the dissolution rate of common acrylic adhesive residues. Automated lens-wash cells operating at 40 °C required an increase in dwell time from 45 s in acetone to 120–180 s in IPA to achieve equivalent surface-energy reduction on uncoated polycarbonate. Solvent stress-cracking resistance of polycarbonate exposed to IPA is evaluated by bent-strip testing according to ISO 22088-3; published data for this specific polycarbonate/IPA configuration is limited and must be generated on the target molecular-weight grade.

The comparative data below separate IPA from the solvents most frequently considered for direct replacement.

Property	Unit	IPA	Ethanol	Acetone	n-Propanol
Molecular weight	g/mol	60.10	46.07	58.08	60.10
Boiling point at 101.3 kPa	°C	82.6	78.4	56.2	97.2
Closed-cup flash point	°C	12	13	-20	23
Surface tension at 20 °C	mN/m	21.7	22.1	23.3	23.8
Hansen δD	MPa^0.5	15.8	15.8	15.5	16.0
Hansen δP	MPa^0.5	6.1	8.8	10.4	6.8
Hansen δH	MPa^0.5	16.4	19.4	7.0	17.4
Vapour pressure at 20 °C	kPa	4.4	5.8	24.0	2.0

Ethanol and IPA have similar closed-cup flash points, 13 °C and 12 °C, but ethanol contains a primary hydroxyl group that is more reactive with isocyanate-functional prepolymers; this restricts its use in moisture-cure urethane cleaning where residual solvent can compete for isocyanate sites. n-Propanol shares the same molecular weight as IPA but has a boiling point of 97.2 °C, which extends drying time and can leave odour in flexible packaging lamination. Acetone has a boiling point of 56.2 °C and flash point of -20 °C, requiring lower-temperature exhaust management and classified area control, but it provides higher polar solvency for nitrocellulose and some alkyd resins.

When Isopropyl Alcohol Replaces Denatured Ethanol in Topical Antiseptic Compounding

WHO-based hand rub formulation using IPA specifies 751.5 mL of 99.8% IPA, 14.5 mL of glycerol, 41.7 mL of 3% hydrogen peroxide, and distilled water to 1000 mL, yielding a final IPA concentration of approximately 75% v/v. The addition sequence is fixed: IPA is charged first, peroxide is added before glycerol, and the batch is held 72 h before use to reduce bacterial spores introduced by non-sterile pre-mix components. Replacement of ethanol with IPA changes the residual odour threshold and may affect tack after repeated use. The final formulation must be protected from open-flame sources; flash point of 75% v/v aqueous IPA remains below 30 °C, with the exact value dependent on test method and headspace volume. Methanol content is reported on the certificate of analysis and reviewed against the current USP monograph. This compounding route is a production formula, not a marketing claim; antimicrobial performance must be established on the filled container format under the relevant antiseptic test protocol.

For storage and transfer, neat IPA is classified Flam. Liq. 2, H225; Eye Irrit. 2, H319; STOT SE 3, H336 under CLP. The lower explosive limit is 2.0 vol% and the upper explosive limit is 12.7 vol%. The NIOSH recommended exposure limit is 400 ppm 8-hour TWA and 500 ppm short-term exposure limit. Incompatibility with strong oxidizers such as concentrated nitric acid and hydrogen peroxide requires segregated storage under NFPA 400; transfer pumps with EPDM seals are excluded because EPDM swells after extended contact, and PTFE, FFKM, or 316L stainless wetted parts are specified instead. For warehouse storage beyond 12 months in translucent polyethylene containers, UV-induced auto-oxidation can generate acetone and trace organic peroxides; sealed, amber-tinted containers or opaque HDPE drums reduce this route. Drum pumps used for dispensing into process vessels are bonded and grounded before transfer to prevent static discharge.