Thomas R. Sweet

Determination of aluminum and iron by solvent extraction and gas chromatography

Abstract A method which combines solvent extraction and gas chromatography for the determination of aluminum and iron in the same sample is given. The two metals were extracted into benzene with trifluoroacetylacetone and a portion of the benzene layer was injected into a gas Chromatograph. The two chelates gave well resolved symmetrical peaks. The method was tested by analyzing a National Bureau of Standards alloy, number 162A. Copper and nickel, which would normally interfere when present in large amounts, were masked with picolinic acid. In addition a solvent extraction separation of iron from aluminum and a spectrophotometric determination of iron is described.

Spectrophotometric determination of ascorbic acid

Abstract A spectrophotometric method for determining ascorbic acid based on the redox reaction between a copper (II)-2,2′-biquinoline solution and ascorbic acid was developed. The purple color of the copper (I)-2,2′-biquinoline complex formed in a buffered acetone-water solution was measured at 540 nm. Minerals, sugars, and other vitamins do not interfere when present in quantities usually found in pharmaceutical preparations. Ferrous interference was eliminated by treating the sample solution with the cation-exchange resin Dowex 50W-X12. Several single component and multivitamin formulations were satisfactorily analyzed by this method. Its high sensitivity permits measurements of quantities of ascorbic acid to 3.4 μg/ml of sample solution. The procedure is simple, rapid, and suitable for routine control.

The formation constants and solvent extraction of lanthanide complexes of 1,1,1,2,2,3,3-heptafluoro-7,7-di-methyl-4,6-octanedione

Abstract A solution of 0.10 M 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione in carbon tetrachloride was used to study the extraction of praseodymium, samarium, europium, gadolinium and terbium by a back-extraction technique. The pKa and the distribution of the reagent between the organic phase and the aqueous phase, 0.10 M (C2H5)4NClO4, were determined. This β-diketone extracted all the lanthanides studied essentially 100% in the pH range of 5.5–8.5. The distribution data can be explained by the presence of M(fod)3 (fod = reagent anion) in the organic phase, and M3+, M(fod)2+, M(fod)3 and M(fod)3OH− in the aqueous phase. The overall stability constants for the aqueous species were determined. The distribution coefficients for the neutral chelates, the KD,MR3·β30 values, the overall extraction constants, and the separation factors were also obtained.

Anion exchange chromatography of transition metals in tartrate medium

Abstract The tartrate complexes of chromium, molybdenum, nickel, silver cadmium and mercury were studied by the batch equilibration method on Dowex 2X-8 anion exchange resin. From the distribution coefficients obtained for the above metals and for manganese, cobalt, zinc and iron, several column separations were developed. Radioisotopes were used in the batch equilibration studies and in the chromatographic separations.

A chemical investigation of the lamprey eel venom.

Abstract The presence of a lipid, a carbohydrate, and a protein were shown in the lamprey eel venom. The protein was dried and its nitrogen content was determined. The ammoacids of the protein were determined qualitatively by means of paper chromatography, and a quantitative determination of the amino acids was done by ion-exchange chromatography.

Determination of manganese in Naiad mollusc shells by neutron activation analysis

Abstract Naiads from two locations 11 river miles apart on the lower Muskingum River in Ohio were studied to determine whether location, calendar year and species could be correlated with the manganese concentration in the shells of the freshwater bivalve molluscs. Neutron activation analysis was used to determine the manganese concentration. The effect of each of these variables on the manganese content of the naiad shells was observed and discussed.