Part A. Chemical neutron activation analysis of aluminum in biological samples. Part B. Stereochemical consequences of chlorine substitution reactions with (2S,3S)dl-2-chloro-3-fluoropentane and (2S,3S)dl-3-chloro-2-fluoropentane in the gas, liquid and solid phase

A. A method was developed for determination of aluminum in biological samples by anion exchange chromatography and neutron activation analysis (NAA). The samples were digested with nitric acid at 65$\sp\circ$C, converting the aluminum to Al$\sp{+3}$. The remaining solids were dissolved with dilute tiron solution, and the pH adjusted to six with ammonium hydroxide. The tiron forms a negative complex with aluminum, which is retained on the anion exchange resin. To remove the interfering ions ($\sp{31}$P, $\sp{24}$Na, $\sp{37}$Cl) present in biological material, ammonium citrate was eluted through the resin. The aluminum was stripped from the resin with nitric acid. Fractions eluting from the column were assayed for aluminum content using NAA. The aluminum recoveries were determined to be quantitative by the method of additive spikes. Urine, bone and tissue samples were analyzed for aluminum content. B. Previously reported recoil halogen-for-halogen substitution reactions of diastereomeric compounds in the gas, liquid and solid phases occurred predominantly with retention of configuration. The stereochemical consequences of translationally excited chlorine-for-halogen substitution reactions in 2,3-dihalopentanes were studied in the gas, liquid and solid phases. (2S,3S)-dl-3-chloro-2-fluoropentane and (2S,3S)-dl-2-chloro-3-fluoropentane were prepared stereospecifically from cis-2-pentane. The purified diastereomers were individually activated by thermal neutrons, and the $\sp{38}$Cl-labeled substitution products separated by capillary-radio-gas chromatography. Two substitution reactions pathways were found. Retention of configuration was determined to be the dominant pathway for $\sp{38}$Cl-for-X (X = Cl,F) substitution reactions. The percent retention of configuration in the $\sp{38}$Cl-for-Cl substitution was found to be phase-dependent, while the $\sp{38}$Cl-for-F substitution was found to be relatively phase-independent. The results of the present study are consistent with previous studies