>Does anyone have the algorith that Thermo uses in Isodat to 
>calculate deltas?  When we go from ratios to delta (for O2) there is 
>differences between our calculations and Isodats on the order of +/- 
>0.01 - 0.02 permil This would not be due to ion corrections since 
>there are none at mass 33 and negligable at mass 34.  Maybe in the 
>way its handling the background?

Greg Michalski, Assistant Professor
http://www.purdue.edu/eas/michalski/
Department of Earth and Atmospheric Sciences
Purdue University
550 Stadium Mall Dr.
Lafayette IN.47907