Comparison of SPE with LLE

Flunitrazepam and morphine are used here as examples for this comparison. 

The comparison between SPE and LLE shows that with LLE both acidic and neutral components such as barbiturates and ibuprofen are detected. This can be seen from Fig. 7-7. 

7-amino-flunitrazepam by solid phase extraction (SPE) compared with liquid-liquid extraction (LLE) 

The sample preparation procedures described above can be used for the majority of drugs of abuse. Exceptions include cannabis, LSD and one or two others. A special preparation technique is used to determine these substances, but this is not discussed further here. 

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