• Journal of the Korean Chemical Society
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• v.54 no.3
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• pp.283-286
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• 2010

A sensitive and reproducible method for the flotation-spectrophotometric determination of zirconium is reported. The method is based on the complex formation zirconium and xylenol orange (XO) which is floated in the interface of aqueous phase and n-hexane by vigorous shaking. By discarding the aqueous solution and n-hexane, the adsorbed complex on to the wall of a separating funnel was dissolved in a small volume of methanol solvent and its absorbance was measured at 429 nm. The effect of different parameters such as pH, concentrations of HCl, and XO, and volume of n-hexane flotation dissolvent, standing and shaking time were studied. The calibration curve was linear in the range of 7-120 ng $mL^{-1}$ of zirconium with a correlation coefficient of 0.9991. The limit of detection (LOD) was 5.8 ng $mL^{-1}$. The relative standard deviation (RSD) for seven replicate measurements of 50 and 110 ng $mL^{-1}$ of zirconium were 4.4 and 3.0%, respectively. The method was successfully applied to the determination of zirconium in water samples.

• Journal of the Korean Chemical Society
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• v.35 no.4
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• pp.389-396
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• 1991

The pre-concentration and determination of ultratrace arsenic in water samples was studied by the precipitate flotation technique. The arsenic in 1.0l of water sample, in which all suspended materials were filtered out, was coprecipitated together with La(OH)$_3$ precipitates at pH 8.5${\pm}$0.1. After the precipitate was made to be hydrophobic by adding mixed surfactant of 1 : 8 mole ratio of sodium oleate and sodium dodecyl sulfate, it was floated with the aid of tiny bubbles of nitrogen gas in a flotation cell. The floated precipitate was quantitatively collected on a micropore glass filter by the suction, dissolved with small volume of 1.0M sulfuric acid, and accurately diluted to 25.00ml with a de-ionized water. Total arsenic was spectrophotometrically determinated by forming silver diethyldithiocarbamate complex of arsine generated from arsenic in the concentrated solution. The calibration curve was linear up to 20ng/ml in the original solution. Analytical results showed that contents of arsenic in a campus wastewater and a river water were 8.2ng/ml and l.0ng/ml, respectively, and their recoveries were 93${\%}$ and 90${\%}$ in water samples which a given amount of arsenic was added into. From above result, it could be concluded that this method was applicable to the determination of arsenic in various kinds of water at low ng/ml levels.