# Commission Regulation (EEC) No 2568/91 of 11 July 1991 on the characteristics of olive oil and olive-residue oil and on the relevant methods of analysis, Division 5.2.1: Preliminary procedure

Extent: E+W+S+N.I.

Fit the column to the gas chromatograph (point 3.3), connecting the inlet port to the on-column system and the outlet port to the detector. Check the gas chromatography apparatus (operation of gas loops, efficiency of detector and recorder system, etc.).
If the column is being used for the first time, it is advisable to condition it. Run a light flow of gas through the column, then switch on the gas chromatography apparatus. Gradually heat until a temperature of 350 °C is reached after approximately 4 h.
Maintain this temperature for at least 2 h, then regulate the apparatus to the operating conditions (regulate gas flow, light flame, connect to electronic recorder (point 3.3.4), regulate oven temperature for column, regulate detector, etc.). Record the signal at a sensitivity at least twice as high as that required for the analysis. The base line should be linear, with no peaks of any kind, and must not have any drift.
Negative straight-line drift indicates that the column connections are not correct while positive drift indicates that the column has not been properly conditioned.

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Source: https://www.legislation.gov.uk/eur/1991/2568/annex/XX/division/5/division/5.2/division/5.2.1 (the official version)
Page: https://openlegislation.uk/eu-regulation-1991-2568/annex-XX/division-5/division-5.2/division-5.2.1
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.