Michael Cefola

Chelation of cobalt, nickel and copper with glutamic acid

Abstract Stabilities of chelates of glutamic acid with bivalent cobalt, nickel, and copper have been determined by potentiometric titration. Stability was seen to increase with electronegativity, second ionization potential, and atomic number of the metal.

The determination of arsenic and antimony in biologic material.

Abstract A method for the estimation of arsenic and antimony in biologic material is presented. It involves the evolution of arsine and stibine into a pyridine solution of silver diethyldithiocarbamate. The resulting color(s) are read spectrophotometrically. A new absorbing column is described which increases sensitivity and facilitates cleaning. Results are tabulated showing the excellent sensitivity and precision attained with the technique. Results of actual Medical Examiner cases are also presented.

Stability constants of 6-mercaptopurine with copper(II) and nickel(II)

Abstract Measurements of the stability constants of 6-mercaptopurine with Cu(II) and Ni(II) show that a stronger complex is formed with copper than with nickel and that 6-mercaptopurine forms a stronger chelate with these cations than those of 6-hydroxypurine or 6-aminopurine. Qualitative tests also indicate possible chelation with Hg(II) and Co(II).

The crystal structure of ammonium tris[4,4,4-trifluoro-1-)2-furyl)-1,3-butanedione]cadmium(II)

Abstract The crystal structure of ammonium tris[4,4,4-trifluoro-1-(2-furyl)1,3-butanedione]cadmium(II), NH 4 [Cd(C 8 H 4 O 3 F 3 ) 3 ], has been determined using 655 visually estimated reflection intensities. Full matrix least squares refinement led to R = 0.086 and Rw = 0.070. The space group is R 3 and there are six molecules in the triply primitive hexagonal cell which has a = 18.46(3) and c = 14.68(2) A . The structure consists of discrete NH + 4 cations, and anions containing hexacoordinated cadmium with the three bidentate ligands related by a crystallographic three-fold axis. The geometry of the coordination sphere is distorted 30–40% from the expected octahedron towards a trigonal prism. This distortion appears to be due to the proximity of the small cation to the coordinating ligand oxygen atoms. X-ray powder patterns of the corresponding chelates of the divalent metals Mn, Fe, Co, Ni and Zn inidcate that these compounds are isostructural with the Cd chelate.

The bromometric determination of bulk enol content of β-diketones that undergo rapid tautomerization

Abstract The bulk enol content observed for the model compound, 2,4-pentanedione as determined by bromometric methods depends on the time interval between addit

Trends in stabilities of some metal chelates of glutamic acid derivatives

Abstract Acid dissociation constants and copper (II) chelate formation constants have been compared for glutamic acid and seven variations of the glutamic acid molecule. Results show the effects of varying the substituents on the ligand molecule, a useful technique when designing chelators for specific purposes. Metal ion specificity was also measured in one case by varying the metal ion with a particular ligand. The constants obtained by several mathematical procedures were in relatively good agreement.

Determination of mercury in biological substances

Abstract A sensitive, simple method for the spectrographic determination of mercury in human tissue and body fluids is presented. The procedure includes an enrichment step wherein the mercury is deposited on copper dust in a manner analogous to column chromatography. Over-all sensitivity is estimated at less than 1 μg of the metal in the sample material. Results are tabulated showing good recovery and reproducibility of amounts up to 10 μg. Levels of mercury found in actual instances of suspected metal intoxication are also presented.

The use of pyridine-2-azo-p-dimethylaniline as an indicator in glacial acetic acid

Abstract Pyridine-2-azo- p -dimethylaniline is suggested as an indicator in the titration of amines (aniline, butylamine, p -phenylenediamine and ethylenediamine) with perchloric acid in glacialacetic acid medium. The precision obtainable is much better than that with crystal violet indicator. The pyridine dye can also be used satisfactorily in the titration of sodium carbonate and sodium acetate.

An evaluation of some simple sulfonic acids as nonaqueous titrants

Abstract The simple aliphatic and aromatic sulfonic acids show evidence of possibilities as new titrants in a glacial acetic acid medium. Excellent precision is obtained in potentiometric titrations with both ethane- and methane sulfonic acids with a standard deviation of 0.2%. Benzenemonosulfonic and naphthalenesulfonic acids both give an average precision of 0.4%. In visual titrations with with crystal violet indicator, the color changes at the end-point are very sharp. The chief advantage of these acids as titrants lies in the fact that they dissolve readily in glacial acetic acid and can be titrated to give reproducible results with the glass-calomel electrode system. None of the sulfonic acids tested was as strong a titrant as perchloric acid, but, unlike perchloric acid, they did not form precipitates or gels in the titration with potassium acid phthalate.

THE PREPARATION AND ISOLATION OF METALLO GLUTAMIC ACID COMPLEXES.

Two methods are described for the preparation and isolation of glutamic acid complexes of some alkaline earth and transition metals. The ammonium salt is also included. Most of the preparations show satisfactory agreement between analytical and theoretical values. Discrepancies may possibly be due to lack of knowledge of the extent of hydration, insufficient re-crystallizations and polymer formation.