Atsushi Mizuike

Effects of matrix on spatial profiles of emission from an inductively coupled plasma

Abstract Effects of easily ionizable elements and other concomitants on spatial profiles of analyte emission were studied in an inductively coupled plasma. The measuring system consists of a self-scanning linear photodiode array mounted vertically in the focal plane of a monochromator and a microcomputer for data acquisition and processing. Easily ionizable elements had complex effects on spatial profiles of analyte emission depending on the excitation characteristics of the spectral lines and the operating parameters of the plasma. On the other hand, sulfuric acid simply depressed the emission over the whole observation height independent of the operating parameters. These data are useful for a better understanding of the complex interference effects found in optimisation experiments and may add to an understanding of the excitation mechanisms responsible for them.

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.

Separation and determination of traces of heavy metals complexed with humic substances in fresh waters by sorption on diethylaminoethyl-sephadex a-25

Abstract Copper(II), lead and cadmium complexed with humic and fulvic acids in filtered 1-l samples of fresh water are sorbed on a column containing 0.5 ml of the macroreticular weak-base anion exchanger, diethylaminoethyl-Sephadex A-25 at a flow rate of 20 ml min −1 . Simple metal cations are not sorbed at all. The sorbed trace metals are quantitatively desorbed with 4 M nitric acid batchwise and determined by graphite-furnace atomic absorption spectrometry. For synthetic aqueous solutions containing traces of heavy metals and humic acid, the results are in conformity with those obtained by cationexchange separation. About 80% of the sorbed humic substances are eluted with 0.5 M sodium hydroxide solution from the A-25 column and its quantity is estimated spectrophotometrically at 400 nm.

Emission spectrometry of solutions with a low-wattage microwave discharge

Abstract A low-wattage microwave discharge for the detection of trace elements in solution has been investigated. Aqueous sample solutions were nebulized by an ultrasonic nebulizer, and the solvent was removed by a desolvation facility before introduction of the aerosol into the discharge. Pronounced inter-element effects, both enhancements and suppressions of the emission, were found. The rotational and excitation temperatures of the discharge were determined, and the former was found to be much lower than the latter.

Separation and determination of traces of heavy metals complexed with humic substances in river waters by sorption on indium-treated amberlite xad-2 resin

A nonionic macroreticular styrene/divnylbenzene copolymer, Amberlite XAD-2 resin is pulverized to 1–10 μm and treated with indium ions to saturate traced of cation exchange sites for the quantitative separation of humic complexes from cations. A 100-ml filtered sample is passed through an indium-treated XAD-2 column (16 diameter, 5 mm tall) at pH 5 at a flow rate of 2 ml min− to sorb heavy metals complexed with humic and fulvic acids. Inorganic cations and anions, EDTA complexes and colloidal hydrated iron(III) oxide are not retained on the column at all. The heavy metals sorbed on the column are then ultrasonically desorbed with 0.5 M nitric acid and determined by graphite-furnace atomic absorption spectrometry. The results fo two river water samples obtained are in good agreement with those obtained when the macroreticular weak-base anion-exchanger DEAE-Sephadex A-25 is used.

Investigation of airborne particles by inductively coupled plasma emission spectrometry calibrated with monodisperse aerosols

Abstract An emission spectrometric method for the investigation of airborne particles has been developed. Sample air was directly introduced into an ICP to vaporize and atomize the particles and to excite the atoms or ions. The emission signal from the ICP was observed as a flash for each particle when the particle concentration was sufficiently low. The flashes were converted into electric pulses, which were counted by a pulse height analyzer. Thus, for particles of homogeneous composition the particle concentration and size distribution were determined simultaneously for a given element. To calibrate the measuring system, monodisperse aerosols were prepared by using a vibrating orifice monodisperse aerosol generator. Sodium chloride, calcium nitrate and copper nitrate aerosols were generated using solutions of known concentrations. The concentration and size distribution of copper particles were determined in aerosols generated by a small arc at the switch of a lamp socket when a 200-W lamp was turned off. Most of the particles were less than 1μm in diameter with a peak distribution at 0.7 μm. The smallest particles measurable for calcium oxide and copper were 0.1 and 0.3 μm in diameter, respectively.

Axial profiles of excitation and gas temperatures in an inductively coupled plasma

Abstract A vertically movable horizontal slit driven by a computer-controlled stepping motor was placed close to the front of the entrance slit of a monochromator. The axial channel of the plasma being imaged onto the entrance slit, the observation height was scanned by slicing the image of the plasma with the horizontal slit. Excitation and gas temperature profiles were calculated under various operating conditions from emission profiles of Fe I and OH lines, respectively. From the axial emission and temperature profiles, two excitational regions governed by different excitation mechanisms were postulated along the axis of the plasma. In the first region from 0 to 8 mm above the load coil, low-energy lines were predominantly excited and their emission profiles were controlled mainly by the dissociation rate of molecules. In the second region from 10 to 20mm above the load coil, high-energy lines were predominant and volatilization interferences were small.

Non-spectroscopic matrix interferences in inductively coupled plasma-mass spectrometry

Abstract Fourteen 0.01 M matrix elements with atomic weight from 7 to 207 (Li, B, Na, K, Cr, Zn, Rb, Mo, Cd, Cs, Sm, Ho, Lu and Pb) have been selected to study their interference effects on analyte (Al, Co, Y, In, La and Tl) signals with a commercial ICP mass spectrometer. The parameters investigated affecting the degree of interference were: mass of matrix element and analyte, ionization potential of matrix element, voltage of the first ion lens element and sampling depth. The matrix effect could not be explained by any single mechanism, e.g. collisions of analyte ions with matrix ions in the supersonic expansion region, space charge effect in the ion optical system and shift in ionization equilibria in the plasma, but by a combination of several mechanisms.

Spectral Interferences in the Determination of Phosphorus in Steel by Inductively Coupled Plasma Emission Spectrometry with an Echelle Monochromator

Spectral interferences in the determination of phosphorus in steel by inductively coupled plasma emission spectrometry is studied by using a computer-controlled, scanning echelle monochromator. There is no direct overlap of an iron line on the phosphorus analysis line, P(I) 213.618 nm, although several iron lines that have not been reported in the literature are observed near the phosphorus line. Scatter light, recombination continuum, and the wing of the Cu(II) 213.598 nm line cause background shift, but the interference can be eliminated by using wavelength modulation and lock-in amplification. The NO band interference arising from the entrainment of air into the plasma is observed when the outer gas flow rate is below 10 liters/min. The detection limit of phosphorus in steel is 0.0006% in the present method.

Computer-controlled programmable monochromator with repetitive optical scanner for accurate peak detection and background correction

Abstract A 0.5-m grating monochromator is controlled by a minicomputer for multi-element analysis of solutions with a microwave-induced argon plasma as light source. The monochromator slews at a rate of 3.4 nm s -1 between wavelengths of analytical interest and remains at a particular wavelength until the measurement is made. A vibrating quartz plate placed behind an entrance slit repetitively scans narrow wavelength regions around the spectral lines of interest. Data acquisition is synchronized with the vibration of the quartz plate so that the profile of each line can be obtained and accurate peak detection and background correction are possible.