Xenobiotic conjugates isolation

In the last decade HPLC has become the most powerful tool the metabolism chemist has for isolating xenobiotic conjugates. 

Dramatic improvements in instrumentation and methods used for the identification of xenobiotic conjugates (and other metabolites), notably proton nuclear magnetic resonance and mass spectroscopy, have significantly influenced the strategies for the isolation of conjugates. The recently developed soft ionization techniques make it possible to obtain useful mass spectral information for a wide variety of intact underivatized xenobiotic conjugates. The state of... 

During the recent years several reviews on the analytical methodology and strategy involved in isolating xenobiotic metabolites, including conjugates have been published,... 

For the sake of convenience the isolation process may be arbitrarily subdivided into several Interdependent steps. The xenobiotic conjugates present in solid matrices must be solubilized and separated from the bulk of other materials concomittantly extracted or present in the original liquid sample (enrichment). 

Thereafter the mixtures of xenobiotic conjugates must be separated into individual fractions (separation) which in turn must be ultimately purified (purification) for spectroscopic identification. As the investigator moves from the enrichment via separation to purification steps the methods require less capacity and selectivity, but greater resolution. Suitable methods have to be selected and arranged in a meaningful sequence in order to obtain an adequate, (i.e. a successful and economical) Isolation strategy. 

Although not a plant xenobiotic conjugate, the metabolism of the glycine conjugate of salicylic acid In Isolated perfused rat kidney has been studied (22). The authors were surprised that 20-30% of the dose was hydrolyzed to salicylic acid In that organ, whereas In parallel experiments the liver did not posses this activity. 

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