Advanced Testing Laboratory

Gas chromatography is the workhorse technique for analysing aromatic materials. It separates a complex mixture into its individual volatile components, so each one can be seen and measured on its own.

How it works

A tiny sample is vaporised in a heated inlet and swept by an inert carrier gas through a long, very thin column lined with a special coating. Compounds that boil at lower temperatures, or that cling less to the coating, travel faster and leave the column first. A detector at the far end records each compound as it emerges.

Reading the result

The output is a chromatogram, a line with a series of peaks:

• The position of a peak (its retention time) shows which compound it is, by comparison with reference standards.
• The size of a peak (its area) shows how much of that compound is present.

Why it matters for essential oils and attars

A natural oil is made up of dozens or even hundreds of compounds, and their proportions form a recognisable fingerprint. GC makes that fingerprint visible, which helps to:

• confirm that an oil matches its expected composition
• spot dilution, added synthetic ingredients or cheaper oils blended in
• check that key marker compounds sit within the expected range
• compare one batch with the next for consistent quality

A Material Safety Data Sheet, now usually called a Safety Data Sheet (SDS), is the standard document that describes a product's hazards and how to handle it safely. It travels with the product through storage, shipping and use.

What it covers

Under the Globally Harmonized System (GHS), an SDS follows a set 16-section format, including:

• product and supplier identification
• hazard classification and labelling
• composition and ingredients
• first-aid and fire-fighting measures
• handling, storage and spill response
• exposure controls and protective equipment
• physical and chemical properties, such as flash point
• toxicological and environmental information
• disposal, transport and regulatory information

Why buyers ask for it

Many aromatic oils are flammable, and some can irritate or sensitise skin. The SDS tells warehouse staff, carriers and customs authorities how to store and move the product, and it tells manufacturers what precautions to take on their production line. A complete, current SDS is a normal requirement for importing and for compliance checks.

Specific gravity compares the density of a material with the density of water at a stated temperature. It is a simple number with no units: water is 1.000, lighter materials read below it and heavier materials above.

How it is measured

The usual instruments are a pycnometer, a precisely calibrated glass flask that is weighed empty, filled with water and filled with the sample, or a digital density meter. Temperature is held steady, because density changes as an oil warms or cools.

Why it matters

Every pure essential oil has an expected range, shaped by what it contains. Citrus oils, rich in light terpenes, are lighter than water, while oils such as clove, rich in heavier compounds, are denser than water. That makes the reading useful for:

• Purity screening: a value outside the expected range can reveal dilution with a carrier or solvent.
• Batch consistency: the same oil should give a closely matching reading every time.
• Practical conversion: it links weight to volume, which matters when filling, pricing and shipping oils by the kilogram or by the litre.

Specific gravity cannot identify an oil on its own, so it is read together with other tests such as gas chromatography and optical rotation.