A new shipment of essential oil at Lê Mai does not go straight onto the shelf. Before that, it passes through GC-MS verification, lot number records, and cold storage. This piece documents those steps.
The shipment arrives
When a supplier sends a new batch, each drum is fully labelled: botanical name, growing region, production lot, extraction date. Lê Mai only buys from suppliers with full documentation per the EOBBD standard (Essential Oil Botanically and Biochemically Defined).
The drum is opened in a closed room, away from sunlight. Room temperature is kept below 20°C so the lightest molecules, which determine the top note, do not evaporate.
Documentation and origin
Each batch comes with paperwork: Certificate of Analysis (CoA), Safety Data Sheet (SDS), Origin Certificate. The paperwork is scanned and saved alongside photos of the drum and label.
If the oil is organic, it must carry certification from a recognised body (USDA, EU Bio, ECOCERT). If wildcrafted, it must have notes on the harvest source and season.
Missing any of these and the batch is rejected on the spot, never entering inventory. This is the first filter.
A small sample to GC-MS
About 5ml is drawn from the drum, sealed in a small vial, and sent to a GC-MS lab. Gas Chromatography-Mass Spectrometry is the standard chemical analysis method for essential oils.
Results return after 5-7 days, in the form of a constituent list with percentages. Lê Mai compares the result against the benchmark for that oil. For example, spearmint must contain 30-50% l-menthol; below this threshold means adulteration.
Sensory · colour, clarity, scent
Alongside GC-MS comes the sensory check. A single drop on a smelling strip, allowed to dry, observed through each phase of evaporation.
Colour must match the description. Clarity must be right. Top, middle, and base notes must appear in the correct sequence. An unfamiliar note at any stage signals adulteration or oxidation.
The lot number is logged
When both GC-MS and sensory pass, a lot number is generated and entered in Lê Mai's own batch ledger. The number includes: intake date, supplier code, sequence number for the year.
Every product later made with oil from this batch carries the lot reference. When a question arises about a soap bar or a massage oil bottle, tracing it back to the specific oil takes a minute.
Temperature and light
The oil is transferred into dark glass bottles, sealed, placed on shelves in a storeroom at 12-15°C. No direct sunlight, no nearby heat sources.
Some oils are more oxidation-sensitive (citrus, certain resins) and are used first. Others are more stable (sandalwood, vetiver) and can be kept for two to three years.
Each month, a small sample from every batch is retested to confirm quality has not declined. Any lot showing oxidation is used immediately or discarded.
A drum arrives. A batch enters the ledger. A lot number is born.
The oil is not yet on the shelf. Not yet in soap. Not yet with the user. The process begins here.