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This method is suitable for the determination of chlorobutanol (INN) up to a maximum concentration of 0,5 % (m/m) in any cosmetic product, except aerosols.
The content of chlorobutanol measured by this method is expressed as percentage by mass (% m/m) of product.
After appropriate treatment of the product to be analyzed the determination is done by gas chromatography using 2,2,2-trichloroethanol as the internal standard.
All the reagents should be of analytical purity.
Weigh accurately between 0,1 and 0,3 g (p g) of the sample. Place in 100 ml volumetric flask. Dissolve it in ethanol (4.3), add 1 ml of the internal standard solution (4.5) and make up to the mark with ethanol (4.3).
Where
=
retention times, in minutes, of the peaks,
=
peak widths at half height, in millimetres,
=
the chart speed, in millimetres per minute.
Column | I | II |
---|---|---|
Material | Glass | Stainless steel |
Length | 1,80 m | 3 m |
Diameter | 3 mm | 3 mm |
Stationary phase | 10 % Carbowax 20 M TPA on Gaschrom Q 80-100 mesh | 5 % OV 17 on Chromosorb WAW DMCS 80-100 mesh |
Conditioning | 2 to 3 days at 190 oC | |
Temperature: | ||
— injector | 200 oC | 150 oC |
— column | 150 oC | 100 oC |
— detector | 200 oC | 150 oC |
Carrier gas | Nitrogen | Argon/methane (95/5 v/v) |
Flowrate | 35 ml/min | 35 ml/min |
Using five 100 ml volumetric flasks, add 1 ml of the standard solution (4.5) and 0,2, 0,3, 0,4, 0,5, and 0,6 ml of solution 4.4 respectively, and make up to the mark with ethanol (4.3) and mix. Inject 1 μl of each of these solutions into the chromatograph in accordance with the operating conditions described in 6.2.2 and construct a calibration curve by plotting as the abscissa the ratio of the mass of chlorobutanol to that of 2,2,2-trichloroethanol and as the ordinate the ratio of the corresponding peak areas.
For a chlorobutanol content of 0,5 % (m/m) the difference between the results of two determinations in parallel carried out on the same sample should not exceed 0,01 %.
If the result is equal to or exceeds the maximum permitted concentration it is necessary to check the absence of interferences.
ISO 5725.