BUNSEKI KAGAKU Abstracts

Vol. 52 No. 8

August, 2003

Research Papers

Determination of trace elements in squid organs by inductively coupled plasma mass spectrometry and neutron activation analysis

Shinji Oikawa¹, Sung-Jun Song², Takeshi Maeyama¹, Takeshi Kishimoto¹, Kenji Tomura³ and Hideo Higuchi¹

(Received 9 January 2003, Accepted 19 May 2003)

With the aim for an analytical validation of the inductively coupled plasma mass spectrometry method by neutron activation analysis, squid (Todarodes pacificus) was collected from Japanese inshore during 1981 to 1996. The internal organs of squid collected in 1981 to 1988 were dried at 105°C for overnight and ashed for 48 hours at 450°C. Ashed samples were pulverized and homogenized. On the other hand, squid was collected in 1996 for the purpose of concentration factor. The squid was cautiously divided into edible, born, craw, liver, and others by using Teflon scissors and forceps. These samples were also ashed. Determination of nine elements (V, Mn, Fe, Co, Cu, Zn, Rb, Ag and Cd) in the ash and SRM 1572 citrus leaves, SRM 1577b bovine liver, and NIES No. 9 sargasso was carried out by non-destructive neutron activation analysis (INAA) at the TRIGA Mark II reactor of Rikkyo University with the flux of 5×10¹¹ n cm^-2 s^-1. The standards were prepared by impregnating an aliquot of SPEX standard solution into filter paper. For ICP-MS, about 0.5 grams of ash samples and standard reference materials were dissolved into 7 M HNO₃ and then evaporated to dryness. The residue was completely dissolved into 1 M HNO₃ and diluted with pure water. Concentration of 13 elements (V, Mn, Fe, Co, Ni, Cu, Zn, Rb, Ag, Cd, Cs, Ba and Pb) was determined after an addition of internal standard to avoid any instrumental drift. The analytical results of nine elements in squid organs by ICP-MS were agree well with INAA within 10%. Analytical results of the other four elements (Ni, Cs, Ba and Pb) were also confirmed by ICP atomic emission spectrometry, atomic absorption spectrometry and flame photometry techniques. This paper describes the usefulness of ICP-MS for trace elements in squid organs, and an application to determine the concentration factors. Particularly, Co, Zn, Ag, and Cd were concentrated into liver with concentration factors of 10⁵~10⁶. The analysis of trace elements in squid organs was found to be a useful method for studying heavy metal or radioactive contamination in a marine environment.

Keywords : squid; internal organs; heavy metal elements; ICP-MS; neutron activation analysis; concentration factor; marine environment.

Development of a plasma torch sustained by low-flow argon gas and its evaluation of the plasma characteristics and analytical performance for inductively coupled plasma mass spectrometry

Kenjiro Yatabe¹, Masaki Ohata¹, Naoki Furuta¹, Naoki Sugiyama² and Ken'ichi Sakata²

(Received 24 March 2003, Accepted 30 May 2003)

Inductively coupled plasma mass spectrometry (ICP-MS) has a problem of high running cost due to a large consumption of argon gas. In order to solve this problem, a high-efficiency torch (HE torch) was developed as a low-flow argon gas plasma torch for ICP-MS. By using the HE torch, the plasma could be sustained at an argon flow rate of 8 l/min. The sensitivity, the electron number density, the degree of ionization and the ionization temperature of the plasma sustained by the HE torch were evaluated and compared with those of a conventional torch (normal torch). From those results, it was evaluated that the HE torch can be applied to ICP-MS without greatly deteriorating the performance of ICP. Furthermore, it was found that the HE torch had a benefit of a smaller matrix effect due to high concentrations of Na and Ca. The HE torch was applied to a recovery test of tap water and compared with the normal torch.

Keywords : ICP-MS; low-flow argon gas; plasma torch; matrix effect; plasma characteristics.

Development of a desktop-sized thermal lens microscope

Shinichiro Hiki¹, Manabu Tokeshi², Akihide Hibara³ and Takehiko Kitamori^2,3

(Received 9 May 2003, Accepted 13 June 2003)

A desktop-sized thermal lens microscope (DT-TLM) having high sensitivity and wide applicability was developed. The operationality of the DT-TLM compared with that of a big-sized TLM has been remarkably improved by simplifying the optics and optimizing the optical configuration. In order to evaluate the performance, the DT-TLM was applied to the ultrasensitive detection of a non-fluorescent molecule (dye: Sunset Yellow) in water. The concentration dependence of the thermal lens signal (calibration curve) showed good linearity in the range of 1×10^-8~1×10^-7 M. From the value of twice the standard deviation (2σ) of this calibration curve, the lower limit of the quantitative determination was estimated to be 1.10×10^-8 M. The lower limit of detection was estimated as 8.27×10^-9 M from the conditions of the signal-to-noise ratio S/N=2. These obtained values were almost the same as that of the big-sized TLM.

Keywords : thermal lens effect; thermal lens microscope; ultra high sensitive detection; non-fluorescent molecule.

Determination of rare earth elements in river water by fully automated on-line column inductively coupled plasma mass spectrometry using iminodiacetate chelate resin as a column

Seiya Mito¹, Masaki Ohata¹ and Naoki Furuta¹

(Received 24 March 2003, Accepted 17 June 2003)

In order to determine ultra-trace levels of rare earth elements (REEs) in river water, fully automated on-line column inductively coupled plasma mass spectrometry (ICP-MS) using iminodiacetate chelate resin as a column was developed in this study. The determination of REEs in a river-water reference material (SLRS-3) was conducted by using the developed method. The obtained results were in good agreement with the recommended values. This developed method was applied to the determination of REEs in Kanda River, which flows through the center of Tokyo, and the distribution patterns of REEs were evaluated. As a result, the positive anormalies of Gd in REEs patterns were found for both river water filtered with a 0.45 µm membrane filter and that filtered and heated with nitric acid. It is considered that the positive anormaly of Gd can be attributed to the outflow of Gd compounds, which are used for MRI (magnetic resonance imaging) contrast medium.

Keywords : river water; on-line column; ICP-MS; iminodiacetate resin; Gd anormaly.

Preparation of anti-cadmium-EDTA complex monoclonal antibody and its binding specificity

Kei Tawarada¹, Kazuhiro Sasaki², Naoya Ohmura², Norio Matsumoto² and Hiroshi Saiki²

(Received 8 April 2003, Accepted 20 June 2003)

To develop a convenient immunoassay for the detection of heavy metals, an anti-cadmium EDTA monoclonal antibody (So26G8) was prepared and characterized for its binding affinities towards other metal complexes with EDTA. The cross reactivities of the antibody for metal free EDTA and its complexes with Ca, Cu, Fe, Hg, Mg, Ni, Pb and Zn were less than 0.73% compared with Cd-EDTA. The equibrillum binding constant (K_d) towards Cd-EDTA was determined to be 5.9×10^-7 M, and these towards Cu-EDTA, Zn-EDTA and Hg-EDTA were approximately 1.0×10^-4 M. In addition, EDTA complexes with the other metals and metal free EDTA were 1000-fold or 10000-fold greater than K_ds compared with Cd-EDTA. This antibody can be applied to a kinetic exclusion assay to quantify Cd in the presence of EDTA. The dynamic range of the assay was from 4.5 ppb to 2.8 ppm.

Keywords : anti-cadmium EDTA monoclonal antibody; immunoassay; screening; heavy metals.

Trueness and precision of two integration methods in chromatography

Rieko Matsuda¹, Masatake Toyoda² and Yuzuru Hayashi¹

(Received 24 April 2003, Accepted 18 June 2003)

Two integration methods for measuring the peak areas and heights in chromatography are compared with special emphasis on trueness and precision. The most important difference of the methods is the integration region which is determined to cover the entire area of a peak. In the traditional integration method, the integration region can vary depending on the actual noise on the peak signal, but it is fixed for every noisy peak in the other method (called TOCO). For the traditional method, large biases are found and the resulting calibration lines have positive intercepts, but there are no such disadvantages for TOCO. The precision is almost comparable to both the methods. It is concluded that both methods have no significant problems in practical use. A fundamental obstacle of the traditional method, when the standard deviation of measurements is estimated, is pointed out.

Keywords : Chromatography; Precision; Trueness; Accuracy; Integration.

Technical Papers

Simultaneous determination of arsenic, bismuth, antimony and selenium in steels by high power nitrogen microwave induced plasma atomic emission spectrometry coupled with hydride generation technique

Akihiro Matsumoto¹, Atsuyoshi Oheda² and Taketoshi Nakahara²

(Received 10 February 2003, Accepted 15 May 2003)

An annular-shaped high power nitrogen microwave induced plasma atomic emission spectrometry with the hydride generation method is described for the simultaneous determination of arsenic, bismuth, antimony and selenium in steels. Under the optimized experimental conditions, the best attainable detection limits at As I 228.812, Bi I 223.061, Sb I 231.147 and Se I 196.026 nm lines were 7.80, 131, 14.50 and 28.99 ng/ml for arsenic, bismuth, antimony and selenium, respectively. The linear dynamic ranges for As, Bi, Sb and Se were 10 to 30000, 300 to 30000, 30 to 30000 and 100 to 30000 ng/ml in concentrations, respectively. The presence of several diverse elements was found to cause more or less a depressing interference with the proposed technique. Of the several pre-reductants examined, hydrochloric acid for antimony and selenium, and potassium iodide for arsenic were found to be the most preferable to reduce Sb(V) and Se(VI) to Sb(III) and Se(IV), and As(V) to As(III), prior to hydride generation, respectively. When arsenic, bismuth, antimony and selenium in steels were determined simultaneously, a large amount of Fe(III) in the solution caused a severe depressing interference, while the presence of Fe(II) showed little or no significant interference. Of the several interference-releasing agents examined, thiourea was found to be the most preferable to reduce Fe(III) to Fe(II). The concentrations of total arsenic, bismuth, antimony and selenium in steels were determined simultaneously by use of the standard additions method. The results obtained by this method were in good agreement with their certified values.

Keywords : high power nitrogen microwave induced plasma; atomic emission spectrometry; hydride generation method; simultaneous determination of arsenic bismuth antimony and selenium; steels.

Relative sensitivity factors for the analysis of aluminum in iron and titanium matrices by glow discharge mass spectrometry

Shinji Itoh¹, Hitoshi Yamaguchi¹, Nobuo Sakuma², Toshiyuki Hobo³ and Takeshi Kobayashi¹

(Received 9 May 2003, Accepted 3 June 2003)

We sought the concentration dependency of the RSF-values of Al in Fe and Ti matrices, each in 0 to 100 mass% in glow discharge mass spectrometry. For the Fe matrix, we measured 29 iron and steel standard reference materials (SRMs) and two pure aluminum (Fe concentration 0.54 and 0.25 mass%) samples to obtain the RSF-values. Also, we measured 18 titanium alloy SRMs and two pure aluminum (Ti concentration 0.0072 and 0.0059 mass%) samples for the Ti matrix. With regard to the Fe matrix, the RSF-value of the two pure aluminum samples was 1.216, slightly smaller than that of the Fe matrix. However, we could accurately determine Al concentration by using 1.355 as RSF_Al,Fe for a routine analysis with concentration ranges of less than 1 mass%. For the Ti matrix, the RSF_Al,Ti of the 14 titanium alloys, whose Al concentrations were 3 to 8 mass%, was 2.218 and the RSD was 3.98%. The RSF-values of the TiAl intermetallic compound (Al concentration 33.46 mass%) sample and the pure aluminum were 2.495 and 2.488, respectively, which were slightly greater than those of the titanium alloys. Therefore, for the Ti matrix, it will be necessary to compensate the quantification with respective RSF values for concentration ranges above and below 10 mass%.

Keywords : relative sensitivity factor of aluminum; Fe and Ti matrices; glow discharge mass spectrometry.

Storage stability and decomposition products of a cyanide-ion standard solution

Kazuhiro Shikakume¹ and Hisakuni Sato²

(Received 28 April 2003, Accepted 6 June 2003)

The storage stability of a cyanide-ion standard solution (0.1~10 mg l^-1, 1000 mg l^-1) was investigated for 6 months. The concentration of the cyanide-ion solution, the concentration of the alkali to be added, the type of container and the storage temperature were chosen as the factors in the experimental design. The concentration decrease became large when the storage temperature was high at either concentration level of cyanide ion. The concentration change for 6 months in preserving at 5°C was -1.1~-4.8% at 0.1~10 mg l^-1 and was -0.8~-1.6% at 1000 mg l^-1. There was a case in which a solid material that may have been a filler dissolved out from the container, itself, when the cyanide solution was preserved in a high-density polyethylene container over a period of 2 months at 20°C. In addition, the concentrations of the cyanide, ammonium and formate ions after long-term storage(24~38 months) were measured. The concentrations of the ammonium and formate ions were coincident with theoretical concentrations the assumed that one mole of cyanide ion changed into one mole of ammonia and one mole of formic acid.

Keywords : cyanide ion standard solution; storage stability; decomposition products.

Multi-elemental determination of trace elements in deep seawater by inductively coupled plasma mass spectrometry with resin preconcentration

Takashi Sumida¹, Tetsuya Nakazato² and Hiroaki Tao²

(Received 21 April 2003, Accepted 9 June 2003)

A miniaturized column (ca. 3 mm i.d., 40 mm length), packed with a chelating resin (0.2 g) with iminodiacetic acid groups (Muromac A-1), was tested for the preconcentration of trace elements in seawater. After preconcentration, the column was washed with ammonium acetate buffer (pH 5.5) and water to remove the major elements, such as Ca and Mg, and was then eluted with 4 ml of 2 mol l^-1^ nitric acid. Twenty-six trace elements were determined by inductively coupled plasma mass spectrometry and inductively coupled plasma emission spectrometry. The necessary volume of the seawater sample was only 200 ml. The recoveries for most of the elements tested were over 90%, although those for Al, V and Th were around 70%. The trueness and precision were evaluated by analyzing a standard reference material of seawater (NASS-4, NRC Canada). The observed values obtained with the present method showed good agreement with the certified values. The present method was also applied to deep seawater samples collected at Muroto, Japan. A difference in the rare earth element pattern, especially the Ce anomaly, between the deep seawater sample and the surface seawater sample was observed, as well as the differences of the concentrations of many trace elements.

Keywords : column preconcentration; chelating resin; ICP-MS; ICP-AES; deep seawater; trace elements.

Determination of 4-nonylphenol in river-water samples by LC/MS using solid-phase sorbents

Hisatake Narasaki¹

(Received 20 March 2003, Accepted 18 June 2003)

4-nonylphenol in river-water samples was determined by liquid chromatography/mass spectrometry (LC/MS) using solid-phase sorbents. The water-samples contained some inorganic salts and humic substances (humic and fulvic acids). Since humic substances have a wide range of molecular weights, they interfere with the determination of 4-nonylphenol. Water (300 ml) spiked with 100 ng of deuterated 4-nonylphenol (the surrogate) at natural pH was applied to Accell QMA (strong anion-exchange sorbent) and C₁₈ cartridges successively using a concentrator at a flow rate of 20 ml min^-1. Humic substances were sorbed to the Accell QMA cartridge, while 4-nonylphenol and deuterated 4-nonylphenol (surrogate) were mainly sorbed to the C₁₈ cartridge. After the C₁₈ cartridge had been eluted with 5 ml of ethyl acetate, the eluent was dehydrated with anhydrous sodium sulfate. The eluent was evaporated to dryness at 40°C under a stream of nitrogen gas. The residue was dissolved in 1 ml of acetonitrile. The concentration of 4-nonylphenol was determined by the operating conditions as shown in Table 1. When the water-samples were densely colored, the humic substances in them could not be completely removed by the above-mentioned procedure. The determination limit of 4-nonylphenol was 10 ng ml^-1. 4-nonylphenol was chemically decomposed by the action of free chlorine in tap water, while it was not easily decomposed in pure water by boiling.

Keywords : 4-nonylphenol; river water; solid-phase sorbents; liquid chromatography/mass spectrometry.

Preparation of a microplate and its evaluation for spectrophotometric multi-sample determination using homogeneous liquid-liquid extraction

Atsushi Manaka¹, Shukuro Igarashi¹ and Hisashi Suzuki²

(Received 17 April 2003, Accepted 18 June 2003)

Homogeneous liquid-liquid extraction is an excellent method as a rapid, simple and powerful preconcentration technique. On the other hand, there are some problems when this extraction method is used for multi-sample determination with a microplate. Especially, the problems of light passage and the concentration rate concerned with the volume of the sample must be resolved. Three kinds of original microplates {(Type A(96 wells), Type B(8 wells), and Type C(96 wells)} were made and their properties were examined. As a result, the concentration rate was found to be 3.8 fold for Type A, 23 fold for Type B, and 17 fold for Type C. Ninety-six sample solutions containing Fe(II) ion were simultaneously determined in the range of 10^-8 M to 10^-6 M by preconcentration using homogeneous liquid-liquid extraction {perfluorooctanoic acid (PFOA^-)/acetone/H⁺ system}. The total analytical time for one sheet of the original microplate was 15 min.

Keywords : homogeneous liquid-liquid extraction; original microplate; spectrophotometric determination; multi-sample determination.

Notes

Determination of sparteine in human serum by column-switching HPLC with electrogenerated chemiluminescence detection using tris(2,2'-bipyridine) ruthenium(II)

Kazuo Uchikura¹ and Naomi Satou¹

(Received 18 April 2003, Accepted 4 June 2003)

A sensitive column-switching high-performance liquid chromatography with a tris(2,2'-bipyridine) ruthenium(II) electrogenerated chemiluminescence detection method for the determination of sparteine (SP) in human control serum is described. The procedure is based on the enrichment of SP on column 1, followed by transfer of SP to column 2. Column 1 was a Shim-pack MAYI-ODS (10×4.6 mm, SHIMADZU, Tokyo, Japan). Column 2 was a CAPCELL PACK C₁₈ (150×4.6 mm, SHISEIDO, Tokyo, Japan). The electrogenerated chemiluminescence detector was an ECR COMET-3000KANAGAWA (Comet, Kawasaki, Japan). The mobile phase of column 1 was composed of a 15 mM KH₂PO₄ buffer at pH 6.0 containing 10 mM octanesulfonate-CH₃CN (98:2, v/v) and at a flow rate of 0.5 ml/min. The mobile phase of column 2 was composed of 150 mM KH₂PO₄ buffer at pH 4.0 containing 10 mM 1-octanesulfonate-CH₃CN (73:27, v/v) and at a flow rate of 1.0 ml/min. The reagent solution was 0.3 mM Ru(bpy)₃²⁺ in 10 mM H₂SO₄ and at a flow rate of 0.45 ml/min. The sample in the control serum was directly injected to the HPLC. The linear dynamic range was 125 fmol-2 nmol/ml. The mean recovery for 1 nmol/ml was 98%. The limit of quantitation was 125 fmol/ml and the intermediate precision (CV) was 1.8% (1 nmol/ml, n=5).

Keywords : sparteine; chemiluminescence; rutheniumu complex; HPLC.

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