Determination of silica in silicates by formation of 12-molybdosilicic acid and redox titration of molybdenum(III).
An indirect titrimetric method for the determination of silica in silicates is described. A boron trioxide-lithium carbonate (10:1) mixture is used as flux and the melt is dissolved in an acidic molybdate solution to form 12-molybdosilicic acid. The yellow complex is extracted with methyl isobutyl ketone (MIBK) and, after removal of the co-extracted molybdate reagent, is decomposed with alkali. The resultant aqueous phase is acidified and passed through a Jones reductor to convert the molybdenum(VI) into molybdenum(III), which is then titrated with potassium permanganate. The method has high precision and accuracy. Phosphorus, titanium, zirconium and vanadium, in amounts that may occur in silicate rocks, do not interfere; at least 5% P(2)O(5), 5% TiO(2), 2% ZrO(2) and 0.5% V(2)O(5) are permissible. Fluorine (at least 2%) can also be tolerated when lithium metaborate is used as flux.
An indirect sequential determination of phosphorus and silicon by atomic-absorption spectrophotometry
Phosphorus and silicon are determined sequentially as phosphate and silicate in a single aliquot of solution by an amplification procedure. Phosphomolybdic acid, H3PO4(MoO3)12, is formed and selectively extracted away from silicate and excess of molybdate reagent into isobutyl acetate. After adjustment of the acidity of the remaining silicate solution, silicomolybdic acid, H4SiO4(MoO3)12, is extracted into butanol. The twelve molybdate ions associated with each phosphate and silicate ion are determined by direct atomic-absorption spectroscopy in the isobutyl acetate and butanol phases in a nitrous oxide-acetylene flame at 3132 A. With this procedure 0·08 to 1 p.p.m. of phosphorus, and 0·08 to 1·2 p.p.m. of silicon can be determined in the same solution. The most suitable conditions for the determination have been established, and a study of the effect of other cations and anions is presented.
Letting Women in? Gender Mainstreaming in Regional Policies
Gender mainstreaming has over the last ten years become the dominant strategy of integrating gender issues in public policy. This article presents regional policy as a broad and increasingly important policy field to study, and analyses gender mainstreaming in this policy field in the Norwegian and the Swedish contexts. How do problem representations surrounding “gender equality” and “gender mainstreaming” produce meanings of gender as well as construct possibilities for change? The article shows that, despite some differences between the two countries, gender mainstreaming in regional policy can to a large extent be read as meaning “women”. Women are in this context given a narrow subject position and are constructed as lacking what it takes to produce sustainable regional growth. The concluding discussion highlights the relations between the implementation of gender mainstreaming and neo‐liberal political trends.