• Analytical Science and Technology
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• v.5 no.4
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• pp.425-431
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• 1992

The concentration and determination of trace phosphate ion was studied by $La(OH)_3$ coprecipitaiton. Phosphate ions in 1.0L samples were coprecipitated with lanthanium hydroxide at pH 9.5 adjusted with ammonia solution. The precipitates were floated with the aid of mixed surfactant(1:8 sodium oleate/sodium dodecyl sulfate) and nitrogen gas bubbles. The floated precipitate was collected in suction flask from the solution. The precipitate were washed with dil. ammonia solution and dissolved in sulfuric acid. The phosphate ion in the concentrated solution was finally determinated by UV/VIS spectrophotometry using the molybdenium blue method. The proposed method could be applied to the determination of phosphate ion in tap water and river water.

• Bulletin of the Korean Chemical Society
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• v.16 no.7
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• pp.582-588
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• 1995

The preconcentration and determination of trace Cd(Ⅱ), Cu(Ⅱ), Pb(Ⅱ), Mn(Ⅱ) and Zn(Ⅱ) in water samples were studied by the precipitate flotation using La(OH)3 as a coprecipitant. The analytes were quantitatively coprecipitated by adding 3.0 mL of 0.1 M La(Ⅲ) solution in a 1,000 mL water sample and adjusting the pH to 9.5 with NaOH solution. After the addition of the 1:8 mixed surfactant solution of each 0.1% sodium oleate and sodium lauryl sulfate, the solution was stirred with a magnetic stirrer for 10 minutes. The precipitates were floated to the surface by bubbling with nitrogen gas and collected in a small sampling bottle. The precipitates were dissolved in nitric acid and then the solutions were diluted to 25.00 mL with a deionized water. The analytes were determined by flame atomic absorption spectrometry. This procedure was applied to the waste water analysis. This technique was simple, convenient and especially rapid for the analysis of a large volume of sample. And also, from the recoveries of better than 92% which were obtained from real samples, this method could be judged to be applicable to the preconcentration and quantitative determination of trace elements in water samples.

• Journal of the Korean Chemical Society
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• v.38 no.9
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• pp.667-675
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• 1994

The precipitate flotation using $La(OH)_3$ as a coprecipitant was studied for the simultaneous determination of trace three elements in a sea water. Several experimental conditions such as pH, coprecipitant and surfactant were investigated with an artificial sea water. To remove the influence of Cr(VI) the Cr(VI) was reduced to Cr(III) using $NaBH_4$ prior to the flotation. Trace amounts of Cu(II), Co(II) and total Cr in 1.0 l sea water was coprecipitated together with the precipitation of $La(OH)_3$ in the solution of pH 9.8 adjusted with 3.OM NaOH solution. The precipitate was floated by using a mixed surfactant (1 to 8 of each 0.5% ethanolic sodium oleate and sodium dodecylsulfate solution) by bubbling a nitrogen gas. The floats was separated and filtrated from the mother liquor by suction. The precipitate was dissolved in 7.0 M $HNO_3$ solution and then marked to 25.0 ml with a deionized water. These elements were determined by graphite fumace atomic absorption spectrophotometry. This method was applied to determine the elements in the sea water of the Eastern and Western coasts. And the recoveries were over 90.0% in the samples into which given amounts of the analyte elements were spiked.

• Analytical Science and Technology
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• v.5 no.1
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• pp.51-56
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• 1992

A method to determine the trace level of arsenic in scalp hair by the hydride generation(HG)-inductively coupled plasma(ICP) spectrometry is described. The optimum conditions for the generation of arsine($AsH_3$), and the interference effects from the concomitant ions were studied. Severe interference effect from Ni(II) is circumvented by the coprecipitation of arsenic with $La(OH)_3$. The detection limit of arsenic is 0.3ppm and the arsenic contents in scalp hair ranged 10~20ppb.