Storage of oral fluid as dried spots on alginate and chitosan foam - a new concept for oral fluid collection.

Background: In recent years, there has been a major focus on analyzing drug substances from dried mu l volumes of biological fluids, commonly known as dried matrix spotting. Results: 10 mu l oral fluid, spiked with five basic drugs, was collected and stored as dried spots on alginate and chitosan foam, and subsequently dissolved; the drugs were thereafter isolated with electromembrane extraction and analyzed by LC-MS. The correlation coefficients were above 0.9885 for all drugs in the range 25-1000 ng/ml. The reported RSD values were below 15%. Conclusion: Storage of oral fluid as dried spots on alginate and chitosan foam have been investigated for the first time. The extract obtained after electromembrane extraction was directly compatible with LC-MS, and apparently free from co-extracted matrix components.