BioTrap 500 MS is a new online-extraction column with the advantages that it can be used in a wider pH range, from 2-10. This property makes extract ion of basic compounds at high pH and acidic compounds at low pH. Under those conditions the compounds will be uncharged and will bind with higher affinity to the inner hydrophobic surface. No ion-pair agent is needed in order to obtain high recovery and efficiency, which makes BioTrap 500 MS compatible with mass spectrometry.

Extraction of amines

General extraction method for amines

The BioTrap 500 MS column is pH stable, which means that amines can be extracted at high pH where the substance is uncharged. The uncharged compound has higher affinity to the inner surface of the BioTrap 500 particle which leads to an increase of the recovery. The general method for basic compounds has been applied in the chromathogram in figure 1, where mianserin has been extracted and analysed from serum.

The conditions used for fluoxetine.

The conditions used for propranolol

The conditions used for mianserin

If mass spectromety is used as detector, the pH has to be adjusted in the analytical column so that the amines enter the detector charged.

By using this general extraction method, it becomes easier to develope methods for amines.

Extraction of acids

General extraction method for acids

Extraction of acids is optimal at low pH where the acid is uncharged and will bind with high affinity to the inner surface of the extraction column and give high recovery. This general method can only be applied together with a mass spectrometry, when the injection volume is small, <50 µl, and the acids are charged by adjustment of the pH in the analytical column. Figure 2 shows the separation of naproxen after the extraction with BioTrap 500 MS column using the general method for acids.

The conditions used for naproxen.

More information about BioTrap 500

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