Ikuo Atsuya

Preconcentration by coprecipitation of lead and selenium with Ni/pyrrolidine dithiocarbamate complex and their simultaneous determination by internal standard atomic absorption spectrometry with the solid sampling technique

In order to determine concentrations below pg/kg level of Pb and Se in water sarrples, the direct simultaneous determination of solid samples by graphite furnace-AAS using a miniature cup technique is applied to coprecipitation samples obtained by using a combinat- ion of ammonium pyrrolidine dithiocarbamate (APDC) and Ni as a carrier element. In the present work, the internal standard method was employed for AAS determination. In case of using the internal standard method weighing was not necessary. Examinations on the coprecipitation of Pb and Se with the Ni-APDC complex have been carried out. Detection limits for Pb (11) and Se (IV) are 30 ng and 70 ng/L, respectively, based on 100-mL sample volume. Precision (relative standard deviation of 10 determination- s) of the determination of Pb and Se at concentration of 0.05 pg/L was 6.9 and 4.5 %, respetively.

Determination of vitamin B12 as cobalt by electrothermal atomic absorption spectrometry using the solid sampling technique

SummaryAn investigation has been carried out to establish a rapid method for the determination of vitamin B12 as cobalt in solid pharmaceutical samples by electrothermal atomization atomic absorption spectrometry with the solid sampling technique using an inner miniature cup. Calibration graphs of peak area versus mass of the element were constructed by use of a synthetic reference material (SyRM). The SyRM is prepared by coprecipitation of cobalt ions with magnesium(II) 8-quinolinate. In order to determine the accuracy of the proposed method, three pharmaceutical preparations were analyzed according to the proposed method using standardization against the SyRM and the results obtained compared with those when solutions of the same samples were analyzed by other techniques. There is good agreement between the results obtained from the proposed and the other method. The detection limit for cobalt in a solid pharmaceutical preparation is 0.15 ng/mg (i.e. 4 ng/mg of vitamin B12) for a typical sample mass of 1.0 mg.

A new solid-liquid extraction sampling technique for direct determination of trace elements in biological materials by graphite furnace atomic absorption spectrometry

Abstract A new solid-liquid extraction sampling technique with graphite furnace atomic absorption spectrometry is based on the quantitative extraction of the element of interest from the biological powdered samples into a liquid phase of 1 mol 1 −1 nitric acid solution. Examinations of the conditions for sample preparation using solid-liquid extraction (i.e. the effect of concentration of nitric acid, sample mass and ultrasonication time on the extraction) have been carried out in order to obtain 100% extraction of cadmium, copper, lead and manganese from powdered biological samples to the liquid phase. 100% of extraction of these metals is successfully carried out using 1 mol 1 −1 nitric acid, and separation of solid phase and liquid phase is done by using a centrifuge (20 min, 4000 rev min −1 ). The proposed method is applied to the determination of cadmium and lead at 0.1 μ g −1 levels and of copper and manganese at 10 μ g −1 levels in powdered biological samples. These analytical results are ascertained by microwave induced nitrogen plasma-mass spectrometry. Detection limits for cadmium, copper, lead and manganese are, respectively, 0.012 μ g −1 , 0.829 μ g −1 , 0.082 μ g −1 and 0.125 μ g −1 in solid samples, when 50 mg of powdered biological samples is extracted in 5 ml of 1 mol 1 −1 nitric acid and then 10 μ l of extracted solution is measured. Precisions of the determination (relative standard deviation at five determinations) of cadmium, copper, lead and manganese are 3.4%, 3.1%, 3.9% and 3.1%, respectively.

Direct determination of trace amounts of arsenic in powdered biological samples by atomic absorption spectrometry using an inner miniature cup for solid sampling techniques

ZusammenfassungZur direkten Arsenbestimmung in NBS und NIES-Referenzmaterialien sowie Meeresorganismen durch AAS wurde ein in einen entsprechenden Ofen einsetzbarer Minaturbecher verwendet. Als Matrixmodifikator wurde ein Gemisch von 3 M Schwefel- und 4 M Salpetersäure mit 60 μg Ni benutzt. Die optimalen Bedingungen wurden durch detaillierte Untersuchungen gefunden. Empfindlichkeit und Genauigkeit des Verfahrens wurden mit der Methode der Arsinerzeugung mit nachfolgender AAS oder ICP-AES verglichen. Relative Standardabweichungen von 3–10% für 7–15 ppm As wurden gefunden.SummaryA new easy solid sampling technique with atomic absorption spectrometry by using an inner miniature cup in conjunction with the cupped type furnace was proposed for the direct determination of arsenic in NBS, NIES standard materials and marine organisms. A mixture of 3 M sulfuric and 4 M nitric acid solution containing 60 μg of nickel was successfully used as the matrix modifier for the powdered samples examined. Optimum experimental conditions were determined based upon detailed examinations for the trace amount determination of arsenic in these samples. Analytical sensitivity and accuracy of this method were compared to the arsine generation followed by atomic absorption or ICP emission spectrometry. The standard deviations for 7–15 ppm As were found to be 3–10%.

Direct analysis of solid samples by atomic absorption spectrometry, following preconcentration of trace elements from seawater with 8-hydroxyquinoline

Summary8-Hydroxyquinoline (8-HOQ) was used for the preconcentration of Cd, Cu, Mn, Pb and Zn from seawater prior to their determination by graphite furnace atomic absorption spectrometry using an inner miniature cup for solid sampling technique. The metal ions in seawater were precipitated quantitatively in the pH range 7–8.5 with 8-HOQ alone. The precipitate thus formed was directly analysed by an atomic absorption spectrometer equipped with a specially deviced graphite furnace and miniature cup. The present method was confirmed to be highly reliable for analysis of seawater. Detection limits (3δb) for Cd(II), Cu(II), Mn(II), Pb(II) and Zn(II) are 1.4, 10, 5, 10, and 6 ng l−1, respectively, for the analysis of a 400-ml portion of seawater samples. Corresponding precision of 6–14% is typical for determination 5-fold above the detection limits.

The use of an inner miniature cup for direct determination of powdered biological samples by atomic absorption spectrometry

Abstract An inner miniature cup has been devised for the direct determination of powder samples by Zeeman atomic absorption spectrometry with an electrothermal graphite furnace of a crucible type. The use of Zeeman instruments has solved a problem of the background absorption, and the use of the inner miniature cup has overcome the difficulty of inserting powder samples weighing less than 1.0 mg into a graphite furnace without loss of sample. This method has been applied to the direct determination of Pb, Cd, Zn, Cu, Mn and Cr in NBS standard samples such as bovine liver, orchard leaves etc.,

Preconcentration by coprecipitation of submicrogram amounts of copper and manganese with 8-quinolinol and direct electrothermal atomic absorption spectrometry of the precipitates

Abstract Copper and manganese in water samples at levels at or below the μg kg −1 level are determined by graphite-furnace atomic absorption spectrometry, after coprecipitation with 8-quinolinol followed by direct measurements on precipitate in a specially-designed furnace. The two metal ions are coprecipitated quantitatively in the pH range 7.0–8.5 with magnesium ions as carrier. The detection limits for copper and manganese are 12 and 14 ng kg −1 , respectively, for 300-ml portions of water samples analyzed.

Comparison of standard materials for the establishment of calibration curves in solid sampling graphite furnace atomic absorption spectrometry. Direct determination of copper in powdered biological samples

SummaryThe selection of standard materials for the establishment of calibration curves is one of the most important problems in the direct analysis of biological samples by GFAAS. Three kinds of standard materials, NBS tomato leaves, coprecipitates with magnesium oxinate and Ni/DMG/PAN were investigated. It was found that it is possible to use both the NBS-SRM and the synthetic reference material prepared by coprecipitation with magnesium oxinate as standard materials for the direct determination of copper in several biological samples issued from NBS and NIES. However, too low results are obtained when the synthetic reference material prepared by coprecipitation with Ni/DMG/PAN is used. In order to clarify this, the effects of nickel and magnesium were examined and the role of magnesium was discussed.

Determination of manganese in iron and steels by u.h.f. plasma-torch emission spectrometry

Abstract The determination of manganese in iron and steels by u.h.f. plasma torch spectrometry is described. The intensity of the Mn II 257.16-nm ion line decreased with increasing concentration of iron, whereas the intensity of the Mn I 403.07-nm atom line increased; only the Mn I 279.48-nm atom line showed constant intensity as the concentration of iron increased. This behavior can be explained in terms of plasma temperature. The effects of acids were examined; the influence of small amounts of diverse elements was depressed by a large amount of iron. A simple and rapid method for the determination of manganese in iron and steels was established, the relative standard deviation being 2.6 % for 0.10 % Mn.

Determination of some rare-earth elements by plasma-jet emission spectrometry

Abstract The effects of a magnetic field on spectral intensities in plasma-jet spectrometry were examined, and detection limits for rare-earth elements were calculated. Plasma-jet emission spectrometry was applied to the determination of lanthanum, yttrium and gadolinium in a monazite sample from which thorium had been separated. A standard addition method was used in order to improve accuracy, and the internal standard and background compensation method was applied to measurements of spectral line intensities to achieve good precision. The coefficient of variation was 1.51% for 50 μg La ml −1 .