This method is applicable for the determination of cineole and menthol in production concentrates, finished goods (including aerosols), and raw materials. And determinations may be conducted individually or on both analytes simultaneously. ASSAY of CINEOLE and MENTHOL by GC.
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Principle
The cineole and menthol are extracted into a solvent and analyzed
by GC using benzyl acetate as an internal standard.
Safety:Â Observe proper laboratory safety rules, personal protection, and chemical handling procedures at all times.
Read MSDS before handling chemicals or products.
Be aware of safety precautions when handling aerosol cans.
Apparatus
Hewlett Packard 5890 Series II Capillary Gas Chromatograph
with FID detector and autosampler, or equivalent.
Appropriate software for data analysis (e.g. Chem station)
Volumetric glassware and pipettes
Analytical balance
Ultrasonic bath
Reagents/Chemicals
:
Acetone - AR grade
Standards of known purity
Benzyl acetate - AR grade
Instrument
Conditions :
Column : HP5 (30m x 0.32mm x 0.25u) or equivalent.
Carrier Gas : Helium
Head Pressure : 150 kpa
Make - Up Gas : Nitrogen - 30 mL/min
Split ratio : 50 : 1
Oven Temperature: 90°C
Oven Maximum: 300°C
Initial Time: 6 min
Injector Temperature: 250°C
Detector (FID) Temperature: 260°C
Injection Volume: 1 uL
Note: These are the proposed conditions and are to be used
as a starting point. Column brand and age may affect the chromatography of the
analytes. In order to obtain adequate results, the chromatographic conditions
may need to be adjusted. An experienced chromatographer will be able to do this
without significantly deviating from this procedure. Any changes made to the
method should be recorded in the results.
Procedure
Standards
Internal Standard Solution (ISD) 0.26% w/v benzyl acetate in
acetone. Use 2.0ml per 25ml flask. Standard Weigh 0.01 - 0.03g of each standard
into a 25ml volumetric flask.
Add 2.0 ml ISD and makeup to volume with acetone. Mix well
and ensure compounds are dissolved completely. Approximate Retention Times
Cineole: 2.4 mins
ISD - benzyl acetate: 4.6 mins
Menthol: 4.8 mins
Samples
1. Production Concentrates
Weigh about 0.8g sample into a 25ml volumetric flask and make up to volume with acetone. Take 2mL of the above solution into another 25mL
volumetric flask. Add 2.0 ml of internal standard solution, make up to volume
with acetone and mix well. Filter if necessary.
2. Finished Products
For aerosol cans follow the sampling procedure (TEX 31451)
to obtain a sample of the finished product. Weigh 2.0-3.0g sample into a 25ml
volumetric flask and make up to volume with acetone. Take 2mL of the above
solution into another 25mL volumetric flask. Add 2.0ml of internal standard
solution, make up to volume with acetone and mix well. Filter if necessary.
3. Raw Materials
Prepare the raw material samples in duplicate and compare them with duplicate preparations of the standard.Â
Weigh 0.01-0.03g of the raw material into a 25ml volumetric flask.Â
Add 2.0 ml of internal standard solution and make up to volume with acetone and mix well.Â
Calculations
% w/w = Sample ratio x Standard Concentration (% w/v) x
Sample volume (mL)
                 Standard ratio x Sample weight (g)
where
 Sample ratio = Sample
peak area / ISD peak area
Standard ratio = Standard peak area / ISD peak area
Results :Â Express results as % w/w.
