Aqueous EDTA Research Articles

Thermodynamics of aqueous EDTA systems: Apparent and partial molar heat capacities and volumes of aqueous strontium and barium EDTA

Apparent molar heat capacities and volumes have been determined for Na2SrEDTA (aq) and Na2BaEDTA (aq). Standard state partial molar heat capacities and volumes have been calculated as well as the partial molar properties at 0.1 m ionic strength that are needed for various thermodynamic calculations. Selected enthalpies and stability constants from the literature have been combined with out heat capacities to generate predicted stability constants to 200°C.

Dissolution of Cu 2S in aqueous edta solutions containing oxygen

The mechanism of the reactions taking place in the heterogeneous system: synthetic polydispersive Cu 2S-ethylediaminetetraacetic acid (EDTA)—O 2—H 2O has been investigated. The partial pressure of oxygen and pH of the solution were found to exert a significant effect on the process kinetics. The dissolution rate does not depend, in practice, on the agitation rate and the EDTA concentration exerts an influence only at higher partial oxygen pressures. Dissolution of Cu 2S in aqueous EDTA solutions proceeds in two steps with the formation of CuS as an intermediate. In acid and neutral solutions the final products of dissolution are elementary sulphur and Cu(EDTA) 2- complex ion. The activation energy ΔE = 10.4kJ/mol (2.4 kcal/mol) suggests a diffusion controlled process. In alkaline solutions sulphur is oxidized to the sulphate ion and the dissolution process is kinetically controlled, ΔE = 41.4 kJ/mol (9.9 kcal/mol).

Staining of demineralized cartilage. I. Alcoholic versus aqueous demineralization at neutral and acidic pH.

Demineralization of cartilage with alcoholic EDTA provides cartilage staining that is no better, as measured by scanning microdensitometry, than that of adequately fixed specimens demineralized with aqueous EDTA. Aqueous EDTA is a faster demineralizing agent than alcoholic EDTA. Certain fixatives can preserve maximal proteoglycan staining in articular cartilage even with subsequent rapid demineralization in formate buffer at pH 3.3. Although alcoholic formalin fixation provided optimum quantitative cartilage staining, cetylpyridinium chloride (CPC) in aqueous buffered formalin improved cellular detail, but CPC partially suppressed matrix staining.

Effects of demineralization in an ethanolic solution of triethylammonium EDTA on solubility of bone matrix components and on ultrastructural preservation.

A solution of triethylammonium EDTA in 80% ethanol was evaluated as a demineralizing reagent for bone in comparison with aqueous solutions of EDTA. Biochemical analysis and acrylamide gel electrophoresis of extracts of finely powdered bovine bone showed that most of the macromolecular components of the organic matrix extractable in aqueous EDTA were retained when the triethylammonium EDTA reagent was used. Ultrastructural examination of chick tibias decalcified with the reagents showed a better preservation of cellular morphology, especially the membranous components, and more uniformly distributed ground substance, though slightly less in quantity, when the aqueous reagent was used. Use of the two reagents appears to be complementary, the alkylammonium reagent being more appropriate for use in studies of the organic matrix of bone, including immunohistochemical studies of bone glycoproteins. The aqueous reagent is more appropriate for use in studies of cellular ultrastructure.

Spectrophotometric determination of microamounts of tocopheryl acetate (vitamin E) in multi-vitamin capsules

Micro amounts of vitamin E in multi-vitamin tablets are extracted from aqueous EDTA medium with petroleum ether and are determined after transesterification, by use of iron(III) in the presence of Ferrozine. Vitamin E is determined in concentrations of 40–200 μg per 25 ml of final solution with a relative precision of about 1–2% when the standard addition method is used.

THE REDUCTION AND QUENCHING OF PHOTOEXCITED FLAVINS BY EDTA

Abstract—Riboflavin was irradiated anaerobically in aqueous EDTA solutions over the pH range 2.5–10. In other dye systems (Bonneau and Pereyre, 1975), only the trivalent anion of EDTA was found to have significant reactivity for photoreduction. For riboflavin, the reactivity begins with monoanionic EDTA, and the reactivity is markedly increased as the charge increases. This suggests that the charge on the reductant is more important to the electron transfer process for riboflavin than the formation of a nonhydrogen bonded nitrogen site on EDTA. At high concentrations of EDTA in the pH range 4–8, quenching of the photoreduction occurs, which can be explained by an energy transfer between the excited singlet state of riboflavin and trianionic EDTA, possibly as an association complex. The rate constants for the photoreduction of riboflavin by the monovalent, divalent, and trivalent anions of EDTA are 1.0 times 107M‐1 s‐l, 4.8 times 10′M‐1 s‐l, and 2.0 times 108M‐1s‐1, respectively. The rate constant for the singlet state quenching by trianionic EDTA is 3 times 109M‐l s‐1, and the limiting quantum yield for intersystem crossing for riboflavin in aqueous solution is 0.50 ± 0.05.

Demineralization in organic solvents by alkylammonium salts of ethylenediaminetetra-acetic acid

1. Insoluble salts of alklaine earth metals (e. g. calcium phosphate) dissolve in non-aqueous solvents containing EDTA salts of organic cations (e.g. tetraethylammonium). 2. Bone is efficiently demineralized in ethanolic trimethylammonium EDTA. Retention in the matrix of water-soluble materials (e.g. proteoglycan) is much better than in standard aqueous EDTA demineralization procedures.

Glycosaminoglycans and Glycoproteins Isolated from Rabbit Femur1

1. Complex carbohydrate fractions were extracted successively with 40% aqueous EDTA (pH 7.4) and 6M urea (PH 7.8) FROM ACETONE-DRIED bone powder of rabbit femur. 2. The carbohydrate fraction extracted with EDTA (E=Fr) was separated into five fractions,D1approximatelyD5 by DEAE-Dephadex A-50 column chromatography. Chemical and infrared spectral analyses, and enzymatic digestion indicate that D2 contained lessacidic glycoprotein, D3 contained sialoglycoprotein, D4 contained a low sulfated proteokeratan sulfate-like substance, and d5 contained glycoprotein-bound chondroitin sulfate A plus protein-free chondroitin sulfate A. 3. Two fractions, HU-D1 and HU-D2, were isolated from the carbohydrate fraction extracted with urea (HU-Fr) by successive digestion with collagenase [EC 3.4.99.5] and pronase, followed by gel-filtration on Sephadex G-100 and then DEAE-Sephadex A-50 column chromatography. HU-D1 and HU-D2 contained a low sulfated keratan sulfate-like substance linked to peptide and glycopeptide-bound chondroitin sulfated keratan sulfate-like substance linked to peptide and glycopeptide-bound chondroitin sulfate A, respectively. 4. The present findings indicate that rabbit femur contains low sulfated proteokeratan sulfate-like substances with varying sulfate contents and glycoprotein-bound chondroitin sulfate A as the principal glycosaminoglycans. The macromolecules bound more tightly to the tissue contain much more sulfate than the corresponding loosely bound ones.

The soluble cuticular proteins from three arthropod species: Scylla serrata (decapoda: portunidae), Boophilus microplus (acarina: ixodidae) and Agrianome spinicollis (coleoptera: cerambycidae)

1. 1. Proteins were isolated from cuticles of Scylla serrata, Boophilus microplus and Agrianome spinicollis by extracting each successively with water, squeous KCl and 7 M ure and for the Scylla cuticle also with aqueous EDTA. Boophilus cuticle contained almost no protein soluble in water or aqueous KCl. The protein fractions were analyzed for their amino acid composition and investigated by gel electrophoresis and isoelectric focusing. 2. 2. For any one species the fractions were similar in amino acid composition and each fraction contained a number of proteins. Those from Agrianome had the lowest molecular weights, those from Boophilus the highest. 3. 3. The isoelectric points of the major protein components from Scylla and Agrianome were similar (pH 3·35-pH 5·7) but those from Boophilus were higher (pH 6·7-pH 8·9). 4. 4. The results support an hypothesis that the large number of protein species in cuticles may be brought about by protein polymorphisms.

Glycosaminoglycans isolated from rabbit femur.

Complex carbohydrate fraction (E-Fr) was extracted with 40% aqueous EDTA (pH 7.4) from the acetone-dried bone powders of rabbit femur. E-Fr was separated into five fractions, CPC-S Fr, 0.3 M Fr, 0.5 M Fr, 0.75 M Fr and 1.0 M Fr by the successive chromatography on a CM-Sephadex C-25 column and a CPC (cetylpyri-dinium chloride)-cellulose column. Subsequently, CPC-S Fr was purified by the chromatography on a DEAE-Sephadex A-50 column. The resulting major fraction (CPC-S-M) was identified as a sulfated glycoprotein-like substance carrying a small amount of chondroitin sulfate A. On the other hand, 0.75 M Fr and 1.0 M Fr were purified separately by the rechromatography on a CPC-cellulose column. The purified preparations of 0.75 M Fr and 1.0 M Fr were identified as a glycoprotein-bound chondroitin sulfate A and protein-free chondroitin sulfate A, respectively.

The extraction of chromium (iii) from aqueous edta by solutions of tetra- n-hexylammonium chloride in dichloroethane

When a solution of chromium (III) in aqueous ethylenediaminetetraacetic acid (H 4Y) is equilibrated with a solution of the liquid anion-exchanger tetra n-hexylammonium chloride in 1,2-dichloroethane, only the violet complex CrY(H 2O) − is extracted as the ion pair NR 4 +CrY(H 2O) − (where R = n-hexyl) over the pH range 3.6–6.0. Maximal extraction occurs at pH 4.7 and the extraction constant ▪ The formally neutral species CrHY(H 2-O) and the anionic species CrY(OH) 2- and CrY(OH) 2 3- are not extractable.

Application and evaluation of the lead-adenosine triphosphatase method in skeletal tissue.

Application and evaluation of the lead-ATPase histochemical method in skeletal tissue has demonstrated an intracellular localization of enzyme activity. The skeletal tissue was demineralized for 72 hr in cold 10% aqueous EDTA adjusted to pH 7.2. Frozen sections were cut and placed on cold albumenized slides, oriented, thawed, dried in a cool air stream, and fixed for 10 min in cold (−2 to −3 C) 10% formalin buffered with Na-acetate and adjusted to pH 7.2. The sections were washed, treated with 10% EDTA for 20 min at room temperature, rewashed, and incubated for an optimal period of 30 min at 37 C. in the lead-ATP medium of Wachstein and Meisel. Following incubation the sections were washed, treated for 1 min with 1% (NH4)2S, rewashed, immersed for 30 min in 10% buffered formalin, dehydrated, cleared, and mounted. Evaluation of the substrate specificity suggests that other phosphatases associated with skeletal tissue do not complicate the ATPase reaction.

Methods for the demonstration of lipid applied to compact bone.

Sections of compact bone were cut from the diaphysis of the femur, tibia, and humerus from dogs and monkeys. These sections were either ground thin and decalcified, or decalcified and subjected to frozen sectioning. Decalcification of the sections was effected by immersion in either Decal, 10% formic acid, 10% formic acid-sodium citrate (pH 4.5) or 20% aqueous EDTA. Sections were routinely stained with oil red O, Sudan black B, or Fettrot 7B. In addition, Nile blue A and phosphine 3R were also employed. Sections stained with phosphine were viewed with a fluorescence microscope. Control sections were extracted with lipid solvents prior to application of the staining procedures. The results indicate that lipid is present in compact bone within the osteocytes, lacunae, canaliculi, and organic matrix. The significance of the lipid in these sites, particularly extracellularly, is unknown.