Flotation of traces of silver and copper(II) ions with a methyl cellosolve solution of dithizone.

Microgram quantities of silver and copper(II) ions in aqueous solutions are collected on dithizone precipitates, which are then floated with the aid of small nitrogen bubbles. This separation technique has been successfully applied to the atomic-absorption spectrophotometric determination of down to a tenth ppm of silver and copper in high-purity lead and zinc metals.

Emission spectrometric detection of metal chelates separated by gas chromatography.

An emission spectrometric detector is used in the determination of metal acetylacetonates. Spectra are excited in the plasma of a 2450 MHz electrodeless discharge. Measuring the intensities of the atomic emission lines of aluminium, beryllium and chromium after gas chromatography provides a highly sensitive and selective method for the determination of the acetylacetonates of these metals. Detection limits are 100 ng for aluminium, 0.01 ng for beryllium and 1 ng for chromium. An analytical procedure is proposed for beryllium down to 10 ppm in aluminium.

Solid-liquid extraction as a preconcentration technique in trace element analysis Extraction of trace impurities from metal chlorides.

Microgram quantities of iron, cobalt, copper, zinc and cadmium are extracted with various aqueous, organic and mixed solvents from chlorides of sodium, potassium, nickel, cadmium, barium and lead prepared by evaporation of aqueous sample solutions. An ultrasonic field accelerates the extraction, and satisfactory trace recoveries and separation factors are achieved in several systems within a reasonable time. The application to a polarographic determination and a two-stage separation technique are also described.

Polarographic determination of impurities in high-purity phosphorus.

Square-wave and radio-frequency polarographic techniques in phosphoric acid-potassium chloride media are applied to the simultaneous determination of copper, lead and cadmium in highpurity red phosphorus down to a level of 0.1 ppm. In addition ca. 0.01 ppm of cadmium is determined by R.F. polarography in potassium sulphate base electrolyte after cation-exchange separation.