What does the 300 in PEG-300 mean?

It refers to a nominal average molar mass around 300 g/mol. PEG-300 contains a distribution of chain lengths, not one molecule with an exact mass of 300 g/mol. The average-mass range and test method belong to the selected grade or standard; a single purity percentage does not describe that distribution.

Can PEG-300 directly replace PEG-200 or PEG-400?

Not automatically. Their average chain lengths, hydroxyl values, viscosity and formulation response can differ. Compare viscosity at the same temperature, water limits and the actual formulation or process before changing grades. CAS 25322-68-3 identifies the PEG family and does not establish interchangeability.

Which quality tests are relevant for a PEG-300 purchasing specification?

Useful controls include average molar mass, hydroxyl value in mg KOH/g, water by an agreed Karl Fischer method, acidity, color and viscosity at a stated temperature. For specified EG or DEG impurities, a suitable validated GC procedure may be used. Residual ethylene oxide and other impurities require their own applicable methods and limits. Impurity results are not a measure of one fixed PEG-300 molecule or the full chain-length distribution.

Polyethylene Glycol 300 (PEG-300) CAS 25322-68-3

Polyethylene Glycol 300 (PEG-300, CAS 25322-68-3, EC/List No. 500-038-2) is a water-miscible liquid polyether with two hydroxyl end groups and a nominal average molar mass around 300 g/mol. It is used as a solvent, carrier, humectant and plasticizing aid in industrial and formulated products. The application, water limit, viscosity and relevant impurity requirements determine the appropriate PEG-300 supply specification.

CAS: 25322-68-3
Synonyms: Polyethylene glycol 300; PEG 300; PEG-300; Macrogol 300; Polyoxyethylene glycol 300
Molecular Formula: H(OCH2CH2)nOH; variable chain lengths with two hydroxyl ends and nominal average molar mass around 300 g/mol
Grade: PEG-300; application-specific average-mass range, hydroxyl value, water, acidity, color, viscosity and relevant impurity limits
Package: Packaging and net weight stated in the quotation for the selected grade
EC / List number: 500-038-2

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Product Description

1 Product overview

2 Technical information

3 Quality tests and documents

5 Packaging and quotation

Product overview

PEG-300 consists of chains of different lengths rather than one discrete molecule. At ordinary ambient conditions it is generally a clear, colorless, viscous liquid and absorbs moisture. Its two hydroxyl ends are relevant in esterification and other reactive-polyol applications, where water content and hydroxyl value influence the formulation balance.

Industrial applications include liquid-detergent and hand-cleaner formulations, latex processing and plasticization. For pharmaceutical or other applications requiring a named standard, include that standard in the inquiry so the appropriate grade and documentation can be matched to the requirement. The PEG-300 name alone does not define a pharmacopeial specification.

Technical information

Product	Polyethylene Glycol 300 (PEG-300) CAS 25322-68-3
CAS number	25322-68-3
EC / List number	500-038-2
Molecular formula / identity	H(OCH2CH2)nOH; variable chain lengths with two hydroxyl ends and nominal average molar mass around 300 g/mol
Synonyms	Polyethylene glycol 300; PEG 300; PEG-300; Macrogol 300; Polyoxyethylene glycol 300
Typical physical form	Clear, colorless, viscous liquid at ordinary ambient conditions; water-miscible and hygroscopic
Grade / specification	PEG-300; application-specific average-mass range, hydroxyl value, water, acidity, color, viscosity and relevant impurity limits
Packaging	Packaging and net weight stated in the quotation for the selected grade

Quality tests and documents

A PEG-300 purchase specification can cover average molar mass (g/mol), hydroxyl value (mg KOH/g), water content, acidity, color and viscosity. Hydroxyl value is measured by a suitable titration procedure; water can be determined by an agreed Karl Fischer method. Viscosity results need a test temperature and units: dynamic mPa·s and kinematic mm²/s are different quantities. Any pH comparison also needs the stated aqueous concentration.

We can provide COA (Certificate of Analysis), TDS (Technical Data Sheet) and SDS (Safety Data Sheet) for the quoted PEG-300 grade, together with relevant quality-test documentation. Where ethylene glycol (EG), diethylene glycol (DEG), residual ethylene oxide or other impurity limits are part of the agreed specification, the test records identify the analytes, method and reporting basis. Chromatograms can be provided where chromatography is the applicable method. GC results for specified impurities are different from the molecular-mass distribution of PEG-300.

Related grades and formulation comparisons

PEG-1500 is a related PEG grade to compare by its stated average-mass range, distribution and supplied form. Commercial grade designations can differ, including blended grades. PEG-6000 powder provides a solid-grade comparison for binder or melt-processing requirements. These grades are assessed separately from a PEG-300 liquid-solvent specification; the shared CAS number does not establish direct replacement.

End-group chemistry also matters. MPEG-350 has one methyl-capped end and one hydroxyl end, whereas PEG-300 is a diol. Glycerol ethoxylate G-18 (Glycereth-18) is a glycerol-based, three-arm polyether for a different architecture and formulation comparison. Their functionality and formulation response differ, so neither is treated as a one-for-one substitute for PEG-300.

Packaging and quotation

For a quotation, send the intended use, any required grade or standard, critical quality limits, quantity, packaging preference and destination. Packaging and net weight are stated in the quotation. Keep containers tightly closed to limit moisture uptake and follow the grade-specific SDS for storage, handling and spill control. The photos show packaging formats for reference.

FAQ - Technical & Supply Chain

Q:
What does the 300 in PEG-300 mean?

A: It refers to a nominal average molar mass around 300 g/mol. PEG-300 contains a distribution of chain lengths, not one molecule with an exact mass of 300 g/mol. The average-mass range and test method belong to the selected grade or standard; a single purity percentage does not describe that distribution.
Q:
Can PEG-300 directly replace PEG-200 or PEG-400?

A: Not automatically. Their average chain lengths, hydroxyl values, viscosity and formulation response can differ. Compare viscosity at the same temperature, water limits and the actual formulation or process before changing grades. CAS 25322-68-3 identifies the PEG family and does not establish interchangeability.
Q:
Which quality tests are relevant for a PEG-300 purchasing specification?

A: Useful controls include average molar mass, hydroxyl value in mg KOH/g, water by an agreed Karl Fischer method, acidity, color and viscosity at a stated temperature. For specified EG or DEG impurities, a suitable validated GC procedure may be used. Residual ethylene oxide and other impurities require their own applicable methods and limits. Impurity results are not a measure of one fixed PEG-300 molecule or the full chain-length distribution.

Ordering & Documentation

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