Figure 6. Characterization of soluble PNAG prepared from S. epidermidis biofilm material. A 3-µL sample of the PNAG preparation was hydrolyzed with HCl and analyzed by HPAEC-PAD-ESI-MS. Glucosamine (arrowhead) from the deacetylation of N-acetylglucosamine monomers was recorded by PAD. A 50 µM authentic N-acetylglucosamine solution was subjected to the same procedure as a control.