Medicinal and aromatic plants – industrial profiles

Sampling and analysis technique
In preparation for sampling, several stems of each plant are enclosed in a two-piece spherical,
custom-designed glass vessel, taking care to not damage or stress the plant. The two sections of
the vessel were clamped around the stems and, over the course of several hours, the headspace is
sampled by means of a low-flow vacuum pump. The volatile components were trapped on an
adsorbent resin (tenax or equivalent), which was packed within a desorption tube attached to the
pump. Subsequently, these trapped components were desorbed by means of a short path thermal
desorption unit into a gas chromatograph equipped with a cryo trap. A blank was purged and
analyzed to determine artifacts from the system.
Instruments and conditions used were: a GC/MS (Hewlett Packard 5890/5971) was config-
ured with two matched (50 m, methyl silicone) capillary columns, one inlet, and two detectors
(MSD and FID). The inlet was modified to accept the thermal desorption unit. The cryo trap was
installed at the head of the columns and cooled to 
50ºC by carbon dioxide. Desorption took
place at 220ºC for 4 min. After desorption was completed, the cryo trap was heated to match the
inlet temperature, while the GC temperature was programmed from 35 to 240ºC at 3ºC/min.
Data analysis was by means of a proprietary mass spectrum library and quantitation was deter-
mined by FID area normalization. Because of the complexity of the chromatograms, no corrections
were made for response differences of individual components.
Weisenfeld (1999) had a problem with coelution (which is normally circumvented by the use
of suitable conditions and also by diluting the samples appropriately). This occurred in this case
with a multiple elution consisting of 

-phellandrene, limonene, cis-ocimene and 1,8-cineole.
An exact quantitation of their distribution within the peak could apparently not be determined,
but an approximation can be made by mass spectrometry (Weisenfeld, 1999) and appears in the
Tables 24.8–24.10.
An analysis of this peak showed that in these profiles: limonene dominates in 
L. multifida
, 
L. pinnata
and 
L. heterophylla
; cineole dominates in 
L. viridis
, 
L. dentata
, 
L. lanata
and 
L. spica
. 
L. angustifolia
contains a greater percentage of 

-phellandrene and 
L. stoechas
seems to contain
almost equal amounts of limonene and cineole. Cymene most commonly occurs as the para 
isomer. However, 
L. angustifolia
shows two other isomers of cymene in addition to the 
para form.
The monoterpenes concentration identified in each species could be correlated with the 
actual odour of the plant (Weisenfeld, 1999). Beta-phellandrene is ‘peppery-minty and slightly
citrusy’, contributing to the herbaceous scent of 
L. angustifolia
. Cineole is ‘camphoraceous, cool’,
adding a substantial sharp, penetrating quality to 
L. viridis
, 
L. dentata
, 
L. lanata
and 
L. spica
species. Limonene is either dextro or laevo: D-limonene being ‘sweet citrusy’, whereas 
L-limonene is ‘very clean, not reminiscent of citrus fruits’. Limonene dominates the terpene frac-
tion of the 
L. heterophylla
and contributes to the scent of 
L. stoechas
. Trans-ocimene, the dominant
terpene in 
L. pinnata
and 
L. multifida
, has a ‘warm-herbaceous odor’, enhancing the balsamic
qualities of the carvacrol component.
The sesquiterpenes were shown in the tables as a sum of the various isomers (beta, gamma,
delta etc.) for that particular sesquiterpene. Those sesquiterpenes listed under ‘other sesquiter-
penes’ are mostly unknown, but are usually not the same unknown. The total sesquiterpene 
content of the different species varies notably, from 1.7 per cent in 
L. stoechas
to 35.9 per cent in
L. angustifolia
. The high amount of caryophyllene, along with a considerable amount of
cadinenes, in 
L. angustifolia
contributes to the distinctive woody note found in this species. It 
is not surprising to see a large amount of bisabolenes (sweet-spicy-balsamic) in 
L. pinnata
and 
L. multifida
, enhancing their warm, sweet, spicy scent.

---

258
Maria Lis-Balchin
L
. 
x heterophylla
and 
L. lanata
contain high concentrations of lavandulol. Lavandulol, an isomer
of geraniol, has a ‘warm-rosy odor’, ‘with a slightly spicy note’. This, along with the floral note of
the germacrenes, likely contributes to the uncharacteristically floral note in 
L. heterophylla
.
Borneol, more widely distributed throughout the genus than lavandulol, has a ‘dry-
camphoraceous, woody-peppery odor’, more characteristic of the lavenders. This terpene alco-
hol, along with its acetate and ketone form (camphor), adds to the distinctive warm, minty,
herbaceous aroma of the typical lavender.