Fully automated photocolorimetric method for dissolved silica in oil well water rich in sulfide and bicarbonate.
A fully automated photocolorimetric method for dissolved silica in oil well water rich in sulfide and bicarbonate is proposed; the method is based on yellow silicomolybdic heteropolyacid. To eliminate the interference of sulfide a treatment with bromate is utilized. The analytical range is 1-30 mg L(-1); with the automatically performed dilution it extends up to 300 mg L(-1), RSD 5.5%.
Studies on the elimination of sulfide interference in the potentiometric determination of chloride using ion selective electrodes in a flow injection system
Detailed investigations have been reported on the application of a common procedure using bromate in nitric acid for the removal of the interference of sulfide in the direct potentiometric determination of chloride using silver-based ion selective electrodes in a flow injection system. It is shown that this procedure is not very efficient and carries a high risk of chloride underestimation. With increasing levels of sulfide the oxidation of chloride to elemental chlorine becomes progressively significant and under certain circumstances virtually no chloride is left irrespective of its initial concentration. Hydrogen peroxide in alkaline medium is proposed as a suitable alternative for the efficient removal of sulfide without any adverse effects on the potentiometric method.
THE IRON-ACETOCARMINE METHOD OF FIXING AND STAINING CHROMOSOMES
A short description of this procedure was given in Vol. 55 of the American Naturalist, pp. 573â€”574. The method has now been used almost daily for five years, and certain improvements have suggested themselves. The solution can be prepared by mixing about equal volumes of glacial acetic acid and water. To this is added powdered carmine in excess. The liquid is then â€ ? just brought to boil, cooled, and decanted. To the red solution there are then added a few drops of a solution of ferric hydrate in 50 per cent. acetic acid, to act as a mordant. The amount of iron varies with different objects. Too much produces a precipitate in a short time. The more