BS ISO 20752 pdf free download

BS ISO 20752-2014 pdf free download.Cork stoppers — Determination of releasable 2, 4, 6- trichloroanisol (TCA).
6 Reagents
Use only reagents of recognized analytical grade.
6.1 Hydro-alcoholic solution, 12 % (v/v) (wine simulant).
6.2 Ethanol, with a minimum purity of 95 %.
6.3 Distilled water.
6.4 Sodium chloride (NaCl) p.a.
6.5 Internal standard, (GC-MS) 2,4,6-trichloroanisol (TCA) d 5 , purity ≥98 % or (GC/ECD) 2,3,6–
trichloroanisol, purity ≥99 %.
6.6 2,4,6-trichloroanisol (TCA), purity ≥99 %.
7 Apparatus
The usual laboratory apparatus and, in particular, the following:
7.1 Balance, with a resolution of, at least, 0,1 mg.
7.2 Glass maceration flasks, with a stopper made of glass, metal, or any other material not absorbing TCA and an appropriate capacity to the sample size.
7.3 Glass flasks (vial), with 10 ml minimum capacity (solution shall occupy at least 50 % of the vial capacity) with a septum and an appropriate stopper.
7.4 SPME? fibre.
EXAMPLE 100 μm PDMS.
7.5 Heating source, for the vial (7.3), set between 30 °C and 50 °C.
7.6 Automatic stirring system, for the SPME.
7.7 Appropriate gas, of chromatographic purity.
7.8 Gas chromatograph, with a mass detector, MS, or an electron capture detector, ECD.
7.9 Low-polarity fused silica capillary column.
EXAMPLE Length of 30 m, internal diameter of 0,25 mm, film thickness of 0,25 μm; stationary phase: copolymer of 5 % diphenyl and 95 % dimethyl polysiloxane.
8 Sampling
The size of the sample to be tested shall be in accordance with the sampling standard (ISO 17727) or agreed between customer and supplier.
9 Procedure
9.1 Calibration
The set of calibration solutions for TCA is obtained by adding known concentrations of analyte to the wine simulant. Standard solutions from 0,5 ng/L to 10 ng/L can be used.
The calibration curve obtained shall be evaluated regularly and whenever any large change is recorded by the GC-MS or GC/ECD.
9.2 Sample preparation
Intact straight cork stoppers are subjected to maceration for 24 h ± 2 h at room temperature, using enough wine simulant, to keep the stoppers entirely immersed, and then analyse the macerate.
EXAMPLE 1 20 corks (45 × 24) mm, in a 1 L flask.
EXAMPLE 2 50 stoppers (45 × 24) mm, in a 2 L flask.
For bar-top stoppers, cut off the flange before maceration.
For granulated cork, 40 g of granulated cork are subjected to maceration for 24 h ± 2 h at room temperature in a 2 L flask, using enough wine simulant to keep the granulated cork entirely immersed, and then analyse the macerate.
For cork discs, 20 cork discs are subjected to maceration for 24 h ± 2 h at room temperature in a 0,5 L flask, using enough wine simulant to keep the granulated cork entirely immersed, and then analyse them acerate.
For cork stoppers for sparkling wines, immerse in the wine simulant only the discs of natural cork and 1 cm of the agglomerate without cutting the stoppers, for 24 h ± 2 h at room temperature, and then analyse the macerate.
9.3 SPME
9.3.1 Test portion
Take a volume of the solution to be tested not greater than 50 % of the vial capacity (7.3).
EXAMPLE 1 For a vial (7.3) of 20 mL, take 10 mL, in such a way that the fibre does not touch the liquid.
The test portion should be saturated with NaCl (approximately 0,30 g/mL).
Add the internal standard solution, 12 %, v/v ethanol/water, to the test portion in the vial (7.3) in such a way that the ethanol content and the total volume of the liquid do not change significantly.
EXAMPLE 2 100 µL internal standard solution/10 mL total liquid.
The concentration of the internal standard solution shall be in the calibration curve range and shall be as close as possible to the specification.
9.3.2 Adsorption
Adjust the time and temperature in the headspace, according to the fibre used.
EXAMPLE Fibre PDMS 100 µm, 15 min in the headspace, stirring at a temperature of 35 °C ± 2 °C.BS ISO 20752 pdf download.