External standardisation procedures

Two synthetic internal standards are used (nor-DCA and nor-CA) to perform an external standardisation method. Calibration curves for each compound are built, starting from known amounts of standards ranging from 0.02 pg to 0.2 pg. BA standards are prepared and analysed as described in below in section 5.4.5.3 Analytical, Procedure . 

A disadvantage of the split injection technique is the uncontrollable discrimination with regard to the sample composition. This applies particularly to samples with a wide boiling point range. Quantitation using external standardisation is particularly badly affected by this. Because of the deviation of the effective split ratio from that set up, this value should not be used in the calculation. Quantitation with an internal standard or alternatively the standard addition procedure should be used. 

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