Showing papers on "Phosphotungstic acid published in 1985"

Caesium ion-selective electrode based on 15-crown-5-phosphotungstic acid precipitates

Abstract: A caesium ion-selective PVC membrane electrode based on 15-crown-5-phosphotungstic acid (PW) precipitates as the neutral carrier was prepared. The electrode gave a linear response with a Nernstian slope of 60 mv decade–1 within the concentration range 10–1–10–4M CsNO3. The selectivity and response time of the electrode were investigated and it was found that the electrode exhibited good selectivity for caesium in comparison with alkali, alkaline earth and some transition metal ions. The effects of pH, addition of ethanol and anions present in the test solutions were also studied.

Demonstration of sialic acid groups in the glomerular basement membrane of the rat with phosphotungstic acid at low pH.

Abstract: This paper reports an unrecognized aspect of phosphotungstic acid staining at low pH. It provides an on-section staining method in which sialic acid-containing molecules can be demonstrated in the laminae rarae of the rat glomerular basement membrane. The staining in the basement membrane became negative after perfusion with the following cations: protamine sulphate, hexadimethrine, Alcian Blue, Ruthenium Red and Toluidine Blue. Blocking ws not achieved with Alcian Blue at about pH 1. The staining was also abolished after mild methylation and demethylation restored the contrast. This is suggestive of the involvement of carboxyl groups. Prior digestion with pronase, trypsin and neuraminidase rendered the laminae rarae negative, whereas hyaluronidase, chondroitinase ABC and crude heparinase were without effect. This indicates that sialic acid groups are detected by this method and that heparan sulphate does not interfere. The staining of the epithelial plasma membrane, also carrying sialic acid groups, remained positive after neuraminidase treatment. It is presumed that this method can be applied successfully for detecting changes in the sialic acid content of the laminae rarae in rat glomerular basement membranes under normal and pathological conditions.

Preparation of hydroquinone monoether

Abstract: PURPOSE:To obtain the titled compound useful as a raw material for medicines, perfumes, antioxidants, polymerization inhibitors, stabilizers for synthetic resins, etc., by reacting a hydroquinone with an alcohol in the presence of a heteropoly acid such as phosphomolybdic acid. CONSTITUTION:A hydroquinone of formula I (R is H, alkyl, aryl, etc.; m is 1 or 2; X and Y are H, or both may form naphthalene ring, alkyl, etc.) is reacted with an alcohol of the formula ROH (R is alkyl, alkynyl, etc.) to give a hydroquinone monoether of formula II. In the process, the reaction is carried out in the presence of a heteropoly acid, i.e. heteropolymolybdic acid or heteropolytungstic acid obtained by condensing metal or nonmetal ions selected from P, As, Si, Ge, Sn, Ti, Zr, B, Ce, etc. around molybdic acid or tungstic acid, preferably phosphotungstic acid.