1. Dissolve 100ug DNA in 200ul distilled water.
2. Add MgCL2 and sodium acetate to the final concentration of 15mM and 10mM, respectively.
3. Incubate with 2 units DNAse I at room temperature for 15 minutes.
4. Add ammonium bicarbonate to the final concentration of 100mM, and then incubate with 2mU phosphodiesterase at 37oC in water bath for 2 hours.
5. Add 1 unit of alkaline phosphatase and incubated at 37oC water bath for another 1 hour.
6. Air dry the solution with degraded DNA. Derivalize produced deoxyribose to its aldonitrile acetate form as usual for analysis on GC/MS spectrometer.