E

Protein cr o

FIGURE 6.3 C 1s NEXAFS spectra of protein (albumin), polysaccharides (sodium alginate), lipid(1-Palmitoyl-2-Hydroxy-sn-Glycero-3-Phosphocholine), and nucleic acid (calf thymus DNA). All spectra except that of DNA were recorded with the ALS 7.0.1 STXM. The spectrum of DNA was recorded on ALS 5.3.2 STXM. (Copyright American Society for Microbiology, Lawrence, J.R. et al. Appl. Environ Microbiol: 69: 5543-5554, 2003.)

285 290 295 300 305 Energy (eV)

285 290 295 300 305 Energy (eV)

x-ray analyses also have potential for application to biofilm-floc materials having been used for bacterial cell-metal interaction studies.33

6.2.4.1 STXM Limitations

Limitations to STXM include: suitability of the model compounds relative to biofilm/floc material, data acquisition without undue radiation damage, requirement for very thin samples (<200 nm equivalent thickness of dry organic components, less than 5 micron of water when wet), use of fragile silicon nitride windows, sample preparation, that is, encapsulation in a wet cell, and absorption saturation distortion of analysis in thick regions of a specimen.

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