The quality of dimethyl sulphoxide can make or break sensitive analytical results. Here is what truly defines a high-grade DMSO.
Dimethyl sulphoxide is one of the most widely used solvents in laboratories and chemical industries. It is known for its strong dissolving power, high polarity, and stability across a wide range of temperatures. Whether it is used in chromatography, extraction, pharmaceutical processing, or cell culture work, the quality of dimethyl sulphoxide directly affects the outcome of the method.
Its chemical identity is listed under CAS no. 67 68 5, and many catalogs also write it as 67 68 5. When you search for high-purity material, you will often see it referred to as dimethyl sulphoxide DMSO. Understanding the factors that determine DMSO quality helps labs make the right choice and avoid issues that affect accuracy, safety, or regulatory compliance.
This blog explains the key factors that define high-quality dimethyl sulphoxide and how to evaluate these before selecting a supplier.
Understanding Dimethyl Sulphoxide and Its Identity
Dimethyl sulphoxide is a polar aprotic solvent. It has the ability to dissolve polar and nonpolar compounds, which makes it useful across many types of analysis. It is fully miscible with water and most organic solvents, and it has a high boiling point. These features make it suitable for chromatography, headspace GC analysis, pharmaceutical extraction, and chemical reactions.
The CAS number is an important identifier for correct material selection. The CAS no. 67 68 5 is the global reference for dimethyl sulphoxide. Using the correct CAS number ensures proper documentation, prevents procurement errors, and supports audit requirements in regulated labs.
1. Purity Level and Assay Percentage
Purity is the first and most important factor that determines DMSO quality. High assay percentage ensures that the material behaves consistently in sensitive analytical methods.
Low quality material often contains residual starting materials or process contaminants. These may appear as unexpected peaks in GC or HPLC runs. They can also interfere with extraction or synthesis work. GC grade DMSO is manufactured with tighter purity specifications to ensure that the solvent does not affect signal quality or baseline stability.
2. Water Content and Moisture Sensitivity
Dimethyl sulphoxide is hygroscopic. This means it absorbs moisture easily from the atmosphere. Moisture is one of the biggest factors that affect DMSO quality, especially in chromatography and headspace analysis.
High moisture content can lead to:
- Peak distortion in GC
- Reduced extraction efficiency
- Incorrect quantification
- Lower stability of certain dissolved samples
GC grade dimethyl sulphoxide is processed and packed to maintain extremely low moisture levels. This is critical for residual solvent analysis and other precision methods.
3. Organic Impurity Profile
Trace organic impurities can create serious problems during analysis. Unwanted alcohols, aldehydes, or sulfur containing compounds may appear in chromatograms and interfere with target peaks.
High quality dimethyl sulphoxide undergoes purification steps to remove these impurities. It also passes through strict QC checks where GC, UV, and chemical tests confirm that the impurity levels are within acceptable limits.
4. Residue on Evaporation
Residue on evaporation indicates the amount of non volatile material left behind after the solvent evaporates. For sensitive applications, this value must be extremely low.
High residue can cause:
- Damage to GC injection ports or columns
- Contamination in reaction vessels
- Issues in cell culture work
- Interference in sample preparation steps
Low residue ensures clean evaporation and minimal contamination.
5. UV Absorbance and Spectral Clarity
Pure dimethyl sulphoxide should show low UV absorbance at key wavelengths. High absorbance indicates the presence of contaminants or degradation by products.
This matters because:
- UV impurities distort HPLC runs
- Chromatographic baselines become unstable
- Light sensitive samples may degrade
Quality suppliers measure UV absorbance as part of batch testing to ensure consistency.
6. Color and Physical Appearance
High-quality dimethyl sulphoxide should be transparent and colorless. A yellow color is considered a warning sign in case the product is oxidized or degraded. If there are some floating particles in the liquid or the liquid is cloudy, it means that the material has absorbed moisture or has not been properly filtered.
Appearance checks are very simple and at the same time highly efficient for quick quality assurance.
7. Odor and Sulfur Indicators
DMSO should be nearly odorless. A strong sulfur smell may indicate the presence of dimethyl sulfide or other breakdown compounds.
This affects chemical reactions and can interfere with sensitive analytical equipment.
8. Packaging and Storage Conditions
Packaging plays a major role in solvent integrity.
Poor packaging can lead to:
- Moisture absorption
- Reaction with plastic containers
- Contamination during transport
- Light exposure
High grade dimethyl sulphoxide is often packed in sealed amber glass bottles or metal containers. GC grade DMSO may also be packed under inert gas to prevent oxidation.
Proper packaging ensures that the material maintains its purity until it reaches the user.
9. Stabilizers and Additives
Some grades of DMSO include stabilizers to prevent oxidation.
For general industrial use, this may be acceptable.
However, analytical and chromatography methods often require stabilizer free dimethyl sulphoxide because additives may interfere with results.
Labs must ensure that the grade they are purchasing matches their method requirements.
Grades of DMSO and Their Quality Requirements
There are three common grades of dimethyl sulphoxide:
Technical Grade
Used for industrial applications where purity is not critical.
Analytical Grade
Suitable for laboratory extraction, sample preparation, and general chemical work.
GC Grade
Used for headspace analysis, residual solvent testing, and high-sensitivity chromatographic methods.
This is the grade where moisture, impurities, and residue must be tightly controlled.
Selecting the right grade prevents contamination and ensures that results match method expectations.
How Reliable Suppliers Ensure Consistent DMSO Quality
High-quality dimethyl sulphoxide comes from suppliers who maintain strong internal standards.
They conduct:
- GC testing for organic impurity profiling
- Karl Fischer testing for moisture levels
- UV absorbance tests
- Filtration and cleanroom packaging
- Lot-wise COA documentation
- Traceability back to raw material batches
These processes ensure that CAS no. 67 68 5 product delivered to the user is compliant with analytical requirements.
Common Quality Issues to Watch For
Labs should always look out for:
- Moisture absorption after opening
- Yellowing or color changes
- Plastic container reactions
- Unusual odors
- Visible haze or particles
These signs indicate degraded or contaminated solvent.
Choosing High Quality DMSO Supports Reliable Results
Dimethyl sulphoxide is a key solvent in many analytical and scientific workflows. Its purity, moisture content, color, UV profile, and packaging quality determine how reliable it will be in your methods. When the solvent is clean, stable, and processed to analytical standards, you can trust your results and protect your equipment.
Labs that need high-quality GC-grade dimethyl sulphoxide for headspace and residual analysis can explore the options available through Lab Chemicals. The products are backed by documentation, consistent purity, and the reliability required for accurate and repeatable outcomes. You can choose the grade that matches your method with confidence.
