The polarographic determination of aluminium

New simple and sensitive spectrophotometric determination of fluoride in drinking groundwater has been developed using aluminium-resorcin blue complex. The method is based on the reaction of fluoride with the coloured complex to produce colourless aluminium fluoride complex and releasing of the free ligand. The relationship of the reaction of flu-oride with the complex is sixth-order polynomial function. The reaction reaches equilibrium at fluoride concentration of 0.054 mM. The equilibrium constant (Keq) was calculated as 1.12 × 1014. Beer-Lambert law is obeyed in the range 0.0 - 0.024 mM of fluoride (0.0 - 1.0 mg·L-1). The molar absorptivity at 502 nm is 6.45 × 103 L·mol-1·cm-1. Fluoride concentration higher than 1.0 mg·L-1 can be measured after proper dilution. The sensitivity, detection limit, quantitation limit, and the percentage recovery of 0.75 mg·L-1 fluoride for the method were found to be 0.357 μg·ml-1., 0.07 mg·L-1, 0.2 mg·L-1, and 101.1 respectively.

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Spectrophotometric Determination of Fluoride in Groundwater Using Resorcin Blue Complexes

Acids like hydrogen fluoride, hydrazoic and fluoroacetic have been shown to prevent the germination of ascospores of N. tetrasperma when dormant spores are treated. On the other hand, propionate, cysteine and others are ineffective when used in this way. When activated ascospores were treated, much lower concentrations of the acids were sufficient to poison the spores. As in other systems, these substances are most effective at a pH below their pKa.

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[Physiology of the cell surface of Neurospora ascospores; entrance of anions and non-polar compounds].

The formation of metal chelates of two hydroxytriphenylmethane dyes,viz., aurintricarboxylic acid (Aluminon, AAC) and sulphodichlorohydroxydimethylfuchson dicarboxylic acid (Chrome Azurol S, CAS) has been reviewed. The former forms coloured water soluble chelates with beryllium(II), aluminium(III), copper(II), iron(III), scandium(III), yttrium(III), rare earths, platinum metals, thorium(IV) and uranium(VI). CAS yields coloured chelates with beryllium(II), magnesium(II), aluminium (III), indium(III), copper(II), cadmium(II), titanium(IV), zirconium(IV), hafnium(IV), iron(III), platinum metals, scandium(III), yttrium(III), lanthanum (III), rare earths, thorium(IV) and uranium(VI), in aqueous solution. Results of the detailed studies on the characteristics, compositions and the stabilities of the metal chelates have been reported. The use of the water-soluble chelate formation in the colorimetric determination of the metal ions has been described.

Chelate formation of metals with hydroxytriphenylmethane dyes and its analytical applications

The use of chrome azurol S for the colorimetric determination of quadrivalent vanadium is described. The reagent forms a violet coloured chelate (λmax = = 580 nm) with the metal at pH 4.0±0.2. Beer's law is followed with 0.203 to 3.40 ppm of metal. The sensitivity is 0.02μg/cm2 (Sandell) and 0.2μg/cm2 (practical). Many ions interfere.

E. A. Terry

Papers

The determination of microgram quantities of fluoride