“ISO compliant” is a common line on essential-oil labels. But ISO has no single standard for “essential oil”. Each oil has its own standard, with its own range for each compound. Set the published data on oils grown in Vietnam against those ranges, and some fit, some do not, and for some we have found no standard to compare with at all.
One caution before reading on: most of the figures below are uncorrected GC-MS peak-area percentages, often from a single sample per site, and rarely with a lot number. They are a snapshot of one place at one time, not a commercial range. Area percent is not weight percent explains why this matters.
Cassia: over the ceiling, and missing a compound
Cassia bark oil sampled in Yen Bai, Quang Ngai and Kon Tum contains 93–96% trans-cinnamaldehyde. ISO 3216, the standard for Chinese-type cassia oil (corresponding to TCVN 6029:2008), sets a ceiling of 88%. The standard also requires 3–15% o-methoxycinnamaldehyde, while the analyses of Vietnamese cassia bark oil we were able to read do not report this compound at all; oil distilled from twigs and leaves contains 0.36%.
So Vietnamese cassia bark oil can be of high sensory quality and still not match the chromatographic profile of ISO 3216. There are two explanations. One is that the standard was built for Chinese-type twig-and-leaf oil, so bark oil is a different product. The other is that uncorrected peak-area percentages make the main compound look higher than it is. Either way, an “ISO compliant” label needs to say which standard it was checked against.
There is one more gap: we have not found any paper quantifying coumarin in cassia oil grown in Vietnam. That matters because coumarin must be declared on cosmetic labels in the EU.
Lemongrass: easily at the lower limit
TCVN 11425:2016, equivalent to ISO 3217, requires a carbonyl content of at least 75%, expressed as citral. Four samples of lemongrass from Phu Tho had total citral by GC of 64.2 to 76.2%; two of the four fell below that level. An evaluation of five lemongrass genetic resources kept in Hanoi also concluded that the citral of lemongrass was below the ISO 3217 level, while East Indian lemongrass (Cymbopogon flexuosus) was above its own standard. Two different methods, one by GC and one by carbonyl titration, but both point the same way.
Cajeput: one name, several oils
Analysis of cajeput leaves from six sites in southern Vietnam split them into two groups. Long An (7.3%) and Tay Ninh (23.0%) contain 1,8-cineole. Dong Thap, Phu Quoc, U Minh Thuong and Ba Ria–Vung Tau contain almost no cineole and are rich in sesquiterpenes instead. In central Vietnam cineole is higher: 47.0% in one study, 30.9% at Phong Dien and 25.4% at Huong Tra, near Hue.
Under the one name, cineole runs from 0 to 47%. We have not found an ISO or TCVN standard written specifically for Vietnamese cajeput oil. Chemotype explains how one species can give two quite different oils.
Star anise: a point in its favour, from one sample
A star anise sample from Cao Bang contained 0.42% estragole, below the level of about 2% commonly reported in international reviews. That counts in its favour for safety, but it rests on a single sample. Star anise (Illicium verum) must also be told apart from the toxic Japanese star anise (Illicium anisatum). Japanese star anise’s toxin, anisatin, is not volatile, so it has to be checked on the fruit, not in the oil.
What to ask when a label says “ISO compliant”
- Which standard, with what number and year?
- Was that standard written for this kind of oil: bark or twig-and-leaf, and which chemotype?
- Is the result from the lot you are buying, or from some earlier sample?
For Vietnamese essential oils, lot-by-lot data measured with a consistent method are currently worth more than most of the published literature.
The underlying evidence is in our research section: Part VI. Vietnamese essential oils: composition and chemotypes and Appendix A3. Facts on Vietnamese essential oils.
Sources
- Study on the production and composition of essential oil from Cinnamomum cassia bark in Yen Bai province of Vietnam. Tropical Journal of Natural Product Research 8(4), 6807–6813, 2024.
- Comparison of chemical profile and antibacterial activity of Cinnamomum cassia bark essential oil from three different Vietnamese provinces. Indian Journal of Agricultural Research 59(7), 1060–1067, 2025. (abstract read)
- Chemical profile and biological activities of the essential oil of cinnamon (Cinnamomum cassia (L.) J. Presl) twigs and leaves. Tropical Journal of Natural Product Research 7(11), 5226–5230, 2023.
- Chemical composition and cytotoxic activity of the essential oils of Cymbopogon citratus L. grown in Phu Tho province. Tạp chí Công nghệ Sinh học 14(4), 683–687, 2016.
- Đánh giá chất lượng tinh dầu sả từ các nguồn gen được lưu giữ tại Hà Nội (Evaluation of the quality of lemongrass oil from genetic resources kept in Hanoi). Tạp chí Khoa học Công nghệ Nông nghiệp Việt Nam 01(134), 25–30, 2022. (abstract read)
- Chemical diversity of the Melaleuca cajuputi leaf oils from six locations in southern Vietnam. Agriculturae Conspectus Scientificus 84(4), 391–397, 2019.
- Tinh dầu tràm gió (Melaleuca cajuputi) và sả chanh (Cympobogon citratus) ở miền Trung Việt Nam: những kết quả mới về thành phần hóa học và hoạt tính kháng vi sinh vật (Cajeput and lemongrass oils from central Vietnam: new results on chemical composition). Tạp chí Khoa học và Công nghệ – Trường Đại học Công nghiệp Hà Nội 59(2B), 144, 2023. (abstract read)
- Nghiên cứu chiết tách và xác định thành phần hóa học tinh dầu tràm của huyện Hương Trà tỉnh Thừa Thiên Huế (Extraction and chemical composition of cajeput oil from Huong Tra district, Thua Thien Hue). Tạp chí Phân tích Hóa, Lý và Sinh học 25(1), 35, 2020. (abstract read)
- Nghiên cứu tách chiết tinh dầu cây hồi (Extraction of star anise oil). TNU Journal of Science and Technology 228(05), 191–198, 2023.
- ISO 3216:1997. Oil of cassia, Chinese type. ISO 3217. Oil of lemongrass. TCVN 6029:2008 and TCVN 11425:2016.