BUNSEKI KAGAKU Abstracts

A simple and highly selective and sensitive extraction spectrophotometric method is presented for the determination of trace amounts of zinc in environmental water samples. The method is based on the separation and preconcentration of zinc as its thiocyanate complex by aqueous biphasic extraction and subsequent determination by spectrophotometry. As a chromogenic reagent for the spectrophotometric determination of zinc, 5-(5-Bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]-phenol (5-Br-PAPS) was used. Aqueous biphasic extraction can be performed by dissolving polyethylene glycol and sodium sulfate in a water sample. A rapid phase separation technique for this aqueous biphasic system was developed using thermal convection so that the extraction of zinc can be accomplished within 7 minutes without mechanical centrifugation. The calibration curve is linear in the concentration range of 0〜200 μg L⁻¹ and the determination limit calculated with ten-times the standard deviation of the reagent blank value is 1.6 μg L⁻¹. Interferences from foreign metal ions were removed by separation with aqueous biphasic extraction and masking with suitable reagents for individual metal ions. The proposed method was applied to the determination of zinc in tap water and river water samples. The obtained results were in good agreement with those obtained by inductively coupled plasma atomic emission spectrometry.

The authors have developed a simple, rapid analytical method to be used with water samples for 68 high fish toxicity pesticides. Forty-eight components of those were measured with gas chromatography/mass spectrometry (GC/MS). Twenty components that are difficult to be measured with GC/MS were measured with liquid chromatography/tandem mass spectrometry (LC/MS/MS). For the pesticides to be measured with GC/MS, distilled water with standard pesticides was loaded in a macroporous diatomaceous earth column. As a result of studying the dissolution medium, when 150 mL of ethyl acetate was used, 87〜101% of recovery, which was a satisfactory value, was obtained for all components. As the result of a recovery test with distilled water, mineral water and river water as samples by combining the GC/MS measurement under this condition and the LC/MS/MS measurement for which the sample was directly diluted in acetonitrile, 84〜105% of recovery, which was a satisfactory value, was obtained for all components. The operation time of this method is as short as approximately one hour. Moreover, as an advantage, sample quantities necessary for the analysis are as small as 20 mL for GC/MS and 5 mL for LC/MS/MS ; therefore, the total quantity is 25 mL. It is expected that this method will play an important role for clarifying the causes of fish mortality incidents.

The production area of coffee beans becomes a brand name, which gives reputations for the products, which is related to the price. This leads to room for mislabeling the products by unscrupulous market dealers. A rapid and easy method for the analysis of trace-element composition of coffee beans, which could be a good indicator of their production area, was studied in the present work. Coffee beans of 6 different regions (Brazil, Colombia, Vietnam, Indonesia, Tanzania, Guatemala) were analyzed by using a highly sensitive X-ray fluorescence spectrometer with three dimensional polarization optics. The experimental conditions were optimized so as to analyze 6 elements (Mn, Fe, Ni, Rb, Sr, Ba) in coffee beans, and linear calibration curves were obtained for the quantitative analysis of those elements. The analytical results were used in principal-component analysis to classify the coffee beans according to the geographical origin, which results in a successful characterization of the 6 production areas. It is found that roasted beans can be used with the same criterion as their green beans. Consequently, a rapid and easy way for the characterization of the geographic origin of coffee beans has been established in this study.

A new method was developed for the quantitative determination of heparin and its related compounds. This method is based on color reactions of ternary complex formation among Iron(III), o-carboxyphenylfluorone and heparin in the presence of a nonionic surfactant. Beer’s law was obeyed in the range of 0.1〜1.2 μg/mL for heparin. The molar absorptivity and the relative standard deviation were 4.6 × 10⁶ L mol⁻¹ cm⁻¹ and 1.33% (n = 5), respectively. The effect of some coexisting substances in the reaction have been investigated, and results show that the selectivity of the method is good. The proposed method should be very useful for a simple and sensitive determination of heparin and its related compounds.

The simultaneous determination of inorganic nitrogen species (nitrite, nitrate, and ammonium ions) in lake and river-water samples was examined by ion chromatography. Nitrite and nitrate ions were separated on a monolith type of ODS columns equilibrated with DDAB (dilauryldimethylammonium bromide) using 0.5 M sodium chloride＋5 mM phosphate buffer (pH = 5.0) as the eluent and they were detected by UV at 225 nm. Whereas ammonium ion was detected at 710 nm as an indophenol blue derivative after the post-column reaction of ammonium in the presence of dichloroisocyanurate and 1-naphthol. Calibration curves of all ions showed good linearity (more than R² = 0.998) in the range of 0〜10 mg/L. The concentration and pH of reagents, the length of reaction coil, and the flow rate of eluent were optimized. The detection limits (S/N = 3) of nitrite, nitrate, and ammonium ions were 0.2, 0.7, and 2.7 μg/L, respectively. Also, the repeatability (0.1 mg/L, n = 5) was below 0.15% (retention time), 1.13% (peak area), and 0.88% (peak height). The present method was applied to the simultaneous determination of inorganic nitrogen species in lake and river-water samples. The recovery by analysis of spiked samples was in the rage of 94〜108%.

Formaldehyde (HCHO) is used in the workplace and comes from an adhesive used in the manufacture of resins, plastics, coatings, and fabrics. HCHO emitted from the furniture and walls in the rooms injures the eyes, nose and respiratory organs, and causes allergies, which is called the Sick building syndrome. We designed and synthesized new colorimetric HCHO-sensing molecules that possess an enaminone structure. As an application of a sensing molecule, a hand-held instrument to monitor indoor HCHO gas (FP-30) and formaldehyde test paper (Dr. Sick House) has been developed and is commercially available. The present paper describes technical explanations about the sensing molecule and monitoring devices, as well as their trends.

It has been highly required to analyze environmental or biological micro-particles noninvasively and nondestructively, since they have each characteristic function in the surface and inside the individual particle. Magnetophoretic velocimetry is a novel migration method, that allows us to measure the magnetic susceptibility of a single micro-particle, and can satisfy this requirement. A high magnetic field gradient generated by a superconducting magnet and a pair of pole pieces were used, in order to enhance the sensitivity of magnetophoretic velocimetry. The apparatus for observation of magnetophoresis in the gradient was constructed. The magnetic susceptibility of a micro-droplet adsorbed by a paramagnetic Dy(III) complex was measured, and reciprocally depended on the radius of the droplet. Dy(III) on the interface could be determined from this dependency. Furthermore, a photo-induced spin transition of single microcrystal of Co-Fe Prussian blue analogues could be observed from an abrupt increase of magnetophoretic velocity after pulse laser irradiation.

ABS resin disk certified reference materials (CRMs) for heavy-metal analysis (NMIJ CRM 8105-a, NMIJ CRM 8106-a, NMIJ CRM 8115-a and NMIJ CRM 8116-a) were evaluated using an energy dispersive X-ray fluoresence (ED-XRF) analysis. The homogeneities of elements for both among-disks and within-disk were evaluated by ED-XRF analysis without any sample pre-treatment, which were similar to those evaluated by ICP-MS analysis after a sample digenstion procedure. The normalized XRF sensitivities for Cd, Cr and Pb in different ABS resin disk CRMs were compared, and the differences among them for those ABS resin disks that have similar matrices were observed. Moreover, Hg in those ABS resin disk CRMs was stable for long-term X-ray irradiation during ED-XRF analysis.

A new atomic absorption spectrometry (AAS) equipped with a wavelength-variable laser has been investigated in order to satisfy the potential needs for measuring of the concentration of dense atomic vapor to control the quality of products in the field of manufacturing premises. The application of AAS is limited because the intensity of the hollow cathode lamp (HCL) is so weak that the dynamic range is narrow in spite of its versatility and simple device configuration. A wavelength-variable laser was applied as the light source of AAS. In the case where the center wavelength of the laser was fit to the absorption maximum of Mn, the measurable region of the absorbance would be magnified by more than one hundred compared with the conventional method. The absorbance was proportional not to the Mn solution concentration, but to the logarithm of the concentration in the high absorbance region. The calculated results of the absorbance supported the experimental results.

A methyl benzoate extraction procedure was studied for determining small amounts of phenol compounds in waste in the 4-aminoantipyrine spectrometry. The proposed procedure was as sensitive as the typical chloroform extraction procedure. The precision of repeated tests (n = 4) was ca. 0.7% on phenol solution (0.20 μg as phenol/mL). The detection limit was 0.004 μg as phenol/mL. Good results were obtained in recovery tests using both waste water and river water.

Titania powders with different crystallinity were prepared from alkoxide-derived amorphous titania powders by heat-treatments at temperatures of less than 600°C. The amorphous and anatase contents of titania powders were analyzed by measuring the heat of crystallization in DSC and by X-ray diffraction measurements with the Rietveld method. Amorphous powders showed an exothermic peak due to the crystallization of amorphous to anatase at around 360°C in DSC. The heat of crystallization was 163 J/g. The amorphous contents of titania powders decreased with an increase of the heat-treatment temperature. On the other hand, the amorphous powder began to crystallize under a heat treatment at 300°C in the XRD profile. The intensity of diffraction lines attributed to anatase became stronger with an increase of the heat-treatment temperature. The amorphous contents of titania powders decreased with the heat-treatment temperature in an analysis of the Rietveld method. There are linear relationships between the amorphous contents and the temperature in both results from DSC and the Rietveld methods. We examined the relationship between the crystallinity of the tiatnia powders and their photocatalytic activity. The photocatalytic performances of titania powders were evaluated upon the removal of acetaldehyde. The results showed that the photocatalytic activity of titania powders increased with an increase of the anatase contents.