The determination of traces of ammonium-nitrogen in aqueous solution by optical emission spectrometry with a high-frequency inductively coupled argon plasma source

A method for the determination of low levels of ammonium ion in solution by optical emission spectrometry with an inductively coupled argon plasma source operated at 27 MHz is presented. The ammonium ion is oxidized with sodium hypobromite in alkaline medium, the evolved nitrogen is passed into the argon plasma, and the NH emission intensity produced in the plasma at 336.0 nm is monitored. A practical detection limit of 0.1 μg N ml^-1 for 5-ml aqueous sample solutions has been obtained. The method has been applied to the determination of the exchangeable ammonium content of soil samples.     

Some spectrofluorimetric applications of the cerium(IV)-cerium(III) system

Cerium(III) ions in dilute sulphuric acid medium exhibit a characteristic fluorescence which has its excitation maximum at 260 nm and its fluorescence emission maximum at 350 nm. By utilising the osmium-catalysed redox reaction between cerium(IV) and arsenic(III), microgram amounts of arsenic (7.5–37.5 μg) may be determined by spectrofluorimetric measurement of the ceriurm(III) produced. The principle may be applied to the determination of several other ions which cannot yet be determined by direct spectrofluorimetry, e.g.. Fe(II) (5.6–28 μg), oxalate (8.8–44μg). Osmium(VIII) (0.05–0.2 μg) and iodide (0.6–2.5 μg) may be determined by their catalytic action.     

Atomic emission spectrometry with an induction-coupled high-frequency plasma source: The determination of iodine,mercury, arsenic and selenium

The application of an inductively coupled high-frequency plasma source to the determination of iodine, mercury, arsenic and selenium by atomic emission spectrometry at wavelengths less than 200 nm is described. Optimal conditions have been established, and the spectral interference effects at different atomic lines for each element have been investigated. With the type of instrumentation employed, the determination of iodine at 183.04 nm, mercury at 184.96 nm, arsenic at 189.0 nm and selenium at 196.09 nm is recommended to minimize spectral interferences. No chemical or physical interferences resulting from the influence of foreign ions on the solute vaporization process have been noted.     

Ion-interaction chromatography of dithiocarbamates on βBondapak CN and LiChrosorb RP-8 stationary phases in the presence of tetraalkylammonium salts

Dithiocarbamates are examined by high-performance liquid chromatography on βBondapak CN and LiChrosorb RP-8 bonded phases using ion-interaction with tetraalkylammonium salts. The effects of the tetraalkylammonium cation and its inorganic co-anion on solute retention are considered. The response for sodium diethyldithiocarbamate is linear over the range 1–500 μg ml^?1, with a detection limit of 0.1 μ ml^?.     

Spectroscopy in separated flames-II The use of the separated air-acetylene flame in long path atomic absorption spectroscopy

The application of a separated air-acetylene flame to the determination of several elements by long-path atomic-absorption spectroscopy is described. The factors which govern the stability and reproducibility of the separated flame have been investigated. High sensitivity and stability and low background absorption are obtained in the the determination of zinc, iron, copper, mercury, magnesium and silver by the method described.     

Determination of platinum metals and gold by optical emission spectrometry with a radiofrequency inductively-coupled argon plasma source

Optimum operating conditions in a 2-kW inductively-coupled argon plasma source for the detection of the elements platinum, palladium, rhodium, ruthenium, iridium, osmium and gold have been established. Detection limits obtained for aqueous solutions introduced into the plasma by pneumatic nebulization range from 1.5 ppb (Rh) to 34 ppb (Ir). No interelement effects caused by chemical interference have been observed between the elements investigated or from a number of base metals; several spectral interferences were observed with the spectrometer employed. The effect of the presence of mineral acids on the nebulization of sample solutions is reported.     

Determination of trace amounts of antimony by spectrofluorimetry in hydrobromic acid medium at liquid nitrogen temperature

Trace amounts of antimony(III) may be determined in 6M hydrobromic acid by measurement of the red fluorescence of its bromide complex at -196 degrees , the optimum wavelengths of excitation and emission (360 and 586 nm respectively) being used. Calibration graphs are linear between 0.01 and 0.25 ppm. The effect of the presence of 50-fold molar amounts of 55 foreign ions has been studied. Of the ions studied, only iron(III) and tellurium(IV) interfere, and these may be tolerated at the 50- and 20-fold levels respectively. A 1000-fold molar amount of arsenic(III) causes no interference.     

The application of a piezoelectric scanning Fabry-Perot Interferometer to the study of atomic line sources—III: Use of the channeled spectra produced with a continuum source for studies of the absorption line-width for calcium atoms in flames

An instrumental arrangement has been developed for the interferometric study of the half-width of atomic lines in absorption using a spectral continuum source. The variation of observed half-width of the calcium absorption line at 422·67 nm with calcium concentration has been examined in air-acetylene and nitrous oxide-acetylene flames supported as cylindrical flames with and without flame shielding and at long path burners. Extrapolation of the curves obtained to zero added calcium concentration in the flame may allow for correction for self-absorption and flame characteristics and calculation of collisional broadening half-widths and damping constants (a-parameters).