Neonatal Sprague Dawley rat brain tissue was extracted with methanol, acetonitrile, acetic acid and trifluoroacetic acids (TFA). Among the extractants tested, 0.1 M TFA gave the highest recovery, 73.4 +/- 5.2% (slope of regression of 'added' vs. 'found' and standard error of the slope) of S-sulfocysteine (SSC). The poorest recovery of SSC was found with acetonitrile and 90% methanol extractions (less than 10%). Possible reasons for the low recoveries have been explored. The recovery of SSC from aqueous standards in 0.1 M TFA is 92 +/- 5%. Detection of picomole quantities of SSC has been demonstrated with a combination of the optimized extraction procedures and our previously developed detection system. Supernatant of rat brain homogenate (0.10 M TFA as extractant) was evaporated to dryness in a vacuum centrifuge. Residues were reconstituted with deionized water. Samples were separated on a reversed phase column. The mobile phase was 20 mM aqueous acetate buffer (pH 5.2) containing 0.40 mM cetyl trimethylammonium p-toluene sulfonate and 2 vol.% methanol. Electrochemical detection used dual series gold-mercury amalgam electrodes. For the first time, S-sulfocysteine was detected in normal neonatal rat brain. Its concentration is 0.99 +/- 0.25 pmol/mg brain tissue. The results indicate that TFA, rarely reported an an extractant, efficiently recovers SSC from rat brain tissues.