I can't speak to the usage of APE in biomass calculations, but there are
two different definitions in use in biomedical applications.
APE = AP(e)-AP(b); AP(e) is from an enriched sample, 1, and AP(b) is from a
baseline sample. AP = 100xR/(1+R)
APE' = 100x(Re-Rb)/(1+(Re-Rb))
In our review (1) we discuss these two formulations and work out their
differences in Table 3 (p. 250).
(1) Brenna Corso, Tobias, Caimi, Mass Spectrom Rev 1997
Sep-Oct;16(5):227-58; Erratum in: Mass Spectrom Rev 1997 Nov-Dec;16(6):382
At 10:35 AM 11/1/2001 +0000, you wrote:
>I have been asked about the definition of atom% isotopic Excess (I). which
>is used in the calculation of biomass evolved C.
>I tried a few books to find out but failed. anybody out there who can help?
>Dr Ahmed S Ayoub
>Postdoctoral Research Scientist
>Agriculture and the Environment Division (AEN)
>Harpenden, Hertfordshire AL5 2JQ
>Telephone ++44(0)1582 763133 x2651
>Fax ++44(0)1582 461366