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UDC 668.5 : 620.1
IS0
I N T E R NAT1 O NAL ORGANIZATION FOR STAN DARD IZATl O N
IS0 RECOMMENDATION
R 592
DETERMINATION OF THE OPTICAL ROTATION
OF ESSENTIAL OILS
1 st EDITION
July 1967
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 592, Determination of the Optical Rotation of Essential Oils,
was drawn up by Technical Committee ISO/TC 54, Essential Oils, the Secretariat of which is
held by Repartiçao de Normalizaçao (IGPAI).
Work on this question by the Technical Committee began in 1952 and led, in 1963, to
L
the adoption of a Draft IS0 Recommendation.
In September 1964, this Draft IS0 Recommendation (No. 89) was circulated to all the
IS0 Member Bodies for enquiry. It was approved, subject to a few modifications of an editorial
nature, by the following Member Bodies:
Argentina Italy Spain
Belgium Japan Sweden
Bulgaria Korea, Rep. of Turkey
Netherlands United Kingdom
Chile
Czechoslovakia New Zealand U.S.S.R.
France Poland Yugoslavia
Germany Portugal
Republic
India
Iran of South Africa
Israel Romania
L No Member Body opposed the approval of the Draft.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0
Council, which decided, in July 1967, to accept it as an IS0 RECOMMENDATION.
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ISO/R 592 - 1967 (E)
IS0 Recommendation R 592 July 1967
DETERMINATION OF THE OPTICAL ROTATION
OF ESSENTIAL OILS
1. SCOPE
This IS0 Recommendation specifies a method for determining the optical rotation of essential oils.
2. DEFINITION
By the optical rotation of an essential oil is meant the angle CL through which the plane of polarized
light is rotated by a layer 10 cm thick of this essential oil at a specified temperature.
The wave-length of the radiation employed should be 589.3 f 0.3 nm, the mean of the D lines for
sodium light.
The determination should normally be carried out at a temperature of 20 f 3 OC, the readings
being corrected to 20 OC. Exceptions should be noted in the specifications for particular essential oils.
3. APPARATUS
3.1 Polarimeter
Use a polarimeter of a precision within f 0.03" (f 2'). If it is properly adjusted it should
of O" and also of 180", with distilled water.
give a reading
The instrument should also be checked with a quartz plate of known optical rotation. If a
quarzt plate is not available an aqueous solution of pure anhydrous sucrose may be used
containing 26.00 g of sucrose per 100 cm3 of solution at a temperature of 20 OC, the optical
rotation of this solution being + 34.62" (+ 34" 37' 12") in a 200 mm layer.
The instrument should be kept and operated in a dark room under stable conditions.
3.2 Light source
Use any device giving monochromatic light of wave-length 589.3 f 0.3 nm. For this pur-
pose a sodium vapour lamp is recommended.
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ISO/R 592 - 1967 (E)
3.3 Polarimeter tubes
When the determination of the optical rotation has to be carried out at a tempera
...