An overview on menthae piperitae (peppermint oil) Article · January 013 citations 16 reads 3,439 authors

 
General appearance: A colourless, pale yellow 
or pale greenish-yellow liquid. 
 
Organoleptic 
properties: 
Odour: 
characteristic, penetrating; taste: characteristic, 
pungent, followed by a sensation of cold. 
Acid value: not more than 1.5, determined on 
5.0g diluted in 50ml of the prescribed mixture of 
the solvents. 
Relative density: 0.900-0.916 
Reflective Index: 1.457-1.467 
Optical rotation: -10° to-30° 
 
Fatty oils and resinified essential oil: 
complies with the test for fatty oils and 
resinified essential oils. 
 
Solvent solubility: miscible with ethanol 
(96%), ether and methylene chloride
.
 
General identity tests: Thin-layer and gas 
chromatography for characteristic monoterpene 
profiles.
 
Chemical assays: The monoterpene content 
determined by gas chromatography should be 
1,8-cineole 
(6–14%), 
limonene 
(1–5%), 
menthone (14–32%), menthofuran (1–9%), 
isomenthone (2–10%), menthyl acetate (3–5%), 
menthol (30–55%), pulegone (not more than 
4.0%) and carvone (not more than 1.0%). The 
ratio of 1, 8-cineole to limonene should be 
greater than 2.0. 
 
MAJOR CHEMICAL CONSTITUENTS
3
The major constituents are menthol (30–55%) 
and menthone (14–32%). Menthol occurs 
mostly in the free alcohol form, with small 
quantities as the acetate (3–5%) and valerate 
esters. Other monoterpenes present include 
isomenthone (2–10%), 1,8-cineole (6–14%), a-
pinene (1.0–1.5%), b-pinene (1–2%), limonene 
(1–5%), 
neomenthol 
(2.5–3.5%) 
and 
menthofuran (1–9%).
 
CHROMATOGRAPHY
4
 
Support-coated open-tubular (SCOT) glass 
capillary column (43 m x 0.5mm I.D.) coated 
with SP-1000 was fitted into an aluminium 
support cage. A Packard-Becker 419 gas 
chromatograph equipped with dual flame 
ionization detectors and dual injectors was used. 
The injection port temperature was 190°C and 
detector temperature 190°C. The multilinear 
temperature programmer was used as follows. 
Initial temperature of 64°C was held for 3 min, 
then the temperature was raised at 0.5ºC/min to 
80ºC, then at 5ºC/min to the final temperature 
of 155ºC, with an isothermal hold of 12 min at 
155°C. The carrier gas was helium at a flow-rate 
of cu. 2 ml/mm with nitrogen (18 ml/min) as 
make-up gas. Air flow was 300 ml/min and 
hydrogen flow 30 ml/min. The velocity of the 
carrier gas was about 21.5 cm/sec whilst the 
capacity ratio (k) of the column was 6.5 using 
docosane at 185C.