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....more on calcite, anti-freeze, etc. Scott Carpenter pointed out that... >The problem of anti-freeze is one of how easily it is removed from the >sample - thus solubility of anti-freeze and the porosity of the sample >must be considered. >Also, can't you drain the anti-freeze, clean the saw (thoroughly) and >fill it with water ? Yes, Scott, you are absolutely correct on both of the above points. Also, i think a comparison between samples cut using water & new anti-freeze (followed by cleaning to remove the anti-freeze) might be instructive at the outset... just to see if there are really any differences. >Particulate matter from previous cuttings should not be a problem unless >the pores (if there are any) fill with debris...repeated ultra-sonic >cleaning will help here. The propensity for a process, such as sawing, to cause contamination in a sample is going to increase as sample size (or C & O content) decreases. I don't know what sort of samples Ethan is working with, but with small samples, i don't think even the most scrupulous cleaning measures would be good enough if that sample was cross-contaminated with C- & O- rich particulates (especially other carbonates!). Maybe i sound TOO cautious, but i've had to do too many analyses over again because of stuff just like this! Dave Wayne \_/o \_/o \_/o \_/o \_/o \_/o \_/o \_/o \_/o \_/o \_/o \_/o \_/o Chemical Sciences & Technology Div. CST-8, MSG-740 Los Alamos National Laboratory Los Alamos, NM USA 87545 Phone: 505-665-5933 <OR> 505-667-9868 FAX: 505-665-4737 e-mail: [log in to unmask] http://mwanal.lanl.gov/Homepages/113674 \_/o \_/o \_/o \_/o \_/o \_/o \_/o \_/o \_/o \_/o \_/o \_/o \_/o