A New Procedure for Preparing Uniform Fecal Samples for LSC. Revision.
Interim rept. no. 4, 11 Mar-14 May 80,
CINCINNATI UNIV OHIO DEPT OF ENVIRONMENTAL HEALTH
Pagination or Media Count:
A procedure was developed for preparing uniform fecal samples for LSC counting and study of fecal metabolites. The procedure requires milling of a rat or monkey feces sample with anhydrous Na2SO4 in a stainless steel ball mill. The fine off-white flours that result are passed through a fine wire sieve 18-8 stainless steel wire, 30 holesinch. This sieving increases homogeneity by removing traces of unground material and dietary fiber. Digestion of samples with NaOH and counting total 14C in dioxane-toluene-naphthalene with Cab-O-Sil DTN-C gave reproducible recoveries. This procedure was adequate for 0.25 g and 0.5 g samples but inadequate for 1.0 g samples. In a study of 7 solventdigestants 1 Soluene, 2 NaOH and 3 Protosol extracted the most dpm 14C from feces samples and showed the best reproducibility. Protosol and Soluene digests counted as efficiently in Biofluor as in DTN-C. Ten replicate Soluene digests in Biofluor and 10 replicate NaOH digests in DTN-C showed mean recoveries which matched well NaOH, 40.6 or - 1.0 SD Soluene, 41.3 or - 1.35 SD. Combustion assays for total 14C gave recoveries that agreed well with values obtained by digestion in NaOH, Soluene, and perchloric acid - H2O2. One gram aliquots of 4 milled feces samples were extracted sequentially 3 times with THF and extracted once with Soluene.
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