OMB Meeting Book_9-11-14

ISO/WD

7) Injector temperature: 250 °C

8) Detector temperature: 250 °C

9) Oven temperature program: initial temperature of 60 °C, maintained for 5 min, raised at a rate of 15 °C min-1 up to 165 °C, maintained at this temperature for 1 min and then raised at a rate of 2 °C min-1 up to 225 °C for 20 min.

10) Amount of sample injected: 1.0  l

An example of the GC profile obtained with these conditions is reported in Annex B: Figure B.4

6.11.2 Example 2 - On-column injection mode

1) Column: 100 m length, 0,25 mm internal diameter, 0,2  m film thickness, fused silica capillary column

2) Stationary phase: (cyanopropyl-polysiloxane or equivalent)

3) Carrier gas type: hydrogen

4) Column head carrier gas pressure: 210 KPa (175-225 KPa)

5) Injector temperature: cold

6) Detector temperature: 280 °C

7) Oven temperature program: initial temperature of 60 °C, maintained for 5 min, raised at a rate of 15 °C min-1 up to 165 °C, maintained at this temperature for 1 min and then raised at a rate of 2 °C min-1 up to 225 °C for 17 min.

8) Amount of sample injected: 1.0  l

An example of the GC profile obtained with these conditions is reported in Annex B: Figure B.5

6.12 Resolution

For the accurate quantification of C18:1 TFA (level ≥ 0.5 g/100g fat) , a sufficient resolution between C18:1 trans Δ13/14 and oleic acid (C18:1 Δ9 cis) is required. The resolution is determined with the injection of the qualitative cis/trans C18:1 FAME isomers standard mixture solution (5.13). The resolution is sufficient when R criteria is equivalent or higher than 1.000 (see Annex B: Figure B.3) Inject into the gas chromatograph 1,0 µl of the calibrating solution (5.13). Determine peak width at half height and distance between the left of the chromatogram and the top of peak for C18:1 trans Δ13/14 and oleic acid methyl ester. The resolution criteria R is calculated as follow:

R

) (½)2 ½)1 ( /)1 2 (18.1 W WRt 





Rt

(1)

where

t : distance, in centimetres, between the left of the chromatogram and the top of peak 1 (C18:1 trans Δ13/14);

1R

t : distance, in centimetres, between the left of the chromatogram and the top of peak 2 (oleic acid);

2R

W

: peak width, in centimetres, at half height of peak 1 (C18:1 trans Δ13/14);

½)1 (

W

: peak width, in centimetres, at half height of peak 2 (oleic acid);

½)2 (

The resolution test is acceptable when value calculated for R is equivalent or higher than 1.00 (± 5%)

NOTE

Example of the calculation is given in see Annex B: Figure B.3

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