BUNSEKI KAGAKU Abstracts

The forensic discrimination of adhesive cloth tapes often used in crimes was developed using a high-energy energy-dispersive X-ray fluorescence spectrometer with 3-dimensional polarization optics. The best measurement condition for discrimination of the tape was as follows : secondary targets, Rh and Al₂O₃ ; measurement time, 300 s for Rh and 600 s for Al₂O₃ ; 14 elements (Ca, Ti, Cr, Mn, Fe, Ni, Zn, Sr, Zr, Nb, Mo, Sb, Ba and Pb) were used for discrimination. It is found that the combined information of yarn density and the XRF peak intensity of the 14 elements successfully discriminated 29 out of 31 samples, of which 2 probably had the same origin. This technique is useful for forensic analysis, because it is nondestructive, rapid and easy. Therefore, it can be applied to actual forensic identification.

A simple pretreatment method for the determination of 24S-hydroxycholesterol in human cerebrospinal fluid by gas chromatography/mass spectrometry (GC/MS) has been developed. Esterified cholesterol was saponified by a high concentration of potassium hydroxide (25 M, 1 mL) in a small volume (10 mL) of a conical test tube with a stopper made of glass. Next, free cholesterol was extracted with a small volume of n-hexane. The combined extracts obtained by the twice extraction were then applied on a silica cartridge for solid-phase extraction. A slight amount of 24S-hydroxycholestertol was separated from a large amount of cholesterol using n-hexane and ethylacetate as an elution solvent. 24S-hydroxycholestertol and 27-hydroxycholesterol-26,26,26,27,27-D₅ as an internal standard were converted to trimethylsilyl ethers by the trimethylsilyl (TMS) reagent, and then the TMS derivatives were determined by GC/MS. The method was successfully applied to the determination of 24S-hydroxycholestertol in human cerebrospinal fluid from patients of non-neurodegenerative disorders. The pretreatment method reported here was simple and useful for one multi-specimen material pretreatment.

The measurement of impurities, such as water in a source and purge gas, has been important as the semiconductor technology has developed. Trace-gas analysis is also necessary for improving the accuracy of a standard gas because of a requirement for SI traceability in recent years. The accuracy of a standard gas relates to the sensitivity of analytical methods for gas. This paper reviews highly sensitive methods for impurities, such as carbon dioxide, carbon monoxide, argon, oxygen, nitrogen, and water, in a pure gas for the standard gas. This review paper also includes a limit of detections as well as a theoretical consideration of the principle and the limit of detection.

A novel chemiluminescent reagent, umbelliferone, was proposed for the determination of manganese(II) using a FIA system. Umbelliferone, a derivative of coumarin, reacted with manganese(II) to strongly emit luminescence in the presence of hydrogen peroxide. Copper(II) and cobalt(II) emit luminescence weakly in an alkaline solution containing Umbelliferone and a surfactant. Among the examined surfactants, cetyltrimethylammonium bromide (CTAB) provided the highest enhancement of the CL intensity, approximately 36-times higher than that in the absence of a surfactant. Anionic and nonionic surfactants did not show any effect on the CL intensity enhancement. The flow system used had two channels. A carrier (distilled water, line 1) and a hydrogen peroxide solution (line 2) as a oxidizing agent were pumped at 0.72 cm³/min and 0.34 cm³/min, respectively. A sample solution (pH 9) of 50 μL containing manganese(II), umbelliferone and CTAB was injected into the carrier line. The limit of detection of manganese(II) by the proposed method was 0.8 ppt. The determination range of manganese(II) was from 2.4 to 1000 ppt. The conditions for the determination of manganese(II) were as follows : umbelliferone concentration, 5.0×10⁻⁴ mol/L in sample solution ; H₂O₂, 1.9 mol/L in line 2 ; pH in sample solution, 9 ; CTAB, 5.0×10⁻³ mol/L in sample solution ; reaction temperature, 25°C. The proposed method was applied to the determination of manganese(II) in river-water samples. The results of a trace manganese(II) determination in a standard sample showed good agreement with a certified value.

We describe a simple and sensitive method for the determination of iodie (I⁻) in iodine-enriched eggs (IEs) by high-performance liquid chromatography (HPLC). I⁻ in a 0.05 g portion of egg yolk and 0.5 g of egg white of IEs were extracted by a solid-phase extraction (SPE) procedure with a cation-exchange and anion-exchange SPE cartridges (Oasis MCX and Oasis WAX). The I⁻ extracts were evaporated to dryness under a vacuum, and the residues were reconstituted in an HPLC mobile phase to prepare 1 mL of analytical sample solutions. A 10 μL aliquot of each sample solution was analyzed by ion-pair reversed-phase HPLC with a UV detector at 225 nm. The method gives good sample clean-up. The relative standard deviation for the determination of I⁻, n＝4, in IE yolk and IE white were 0.8 and 5.5％, respectively. The recoveries of 50 μg of I⁻ spiked per g of IE yolk and 2.5 μg of I⁻ spiked per g of IE white were 92.4 and 96.8％, respectively. The detection limits for I⁻, based on S/N＝3, were 0.76 μg per g of IE yolk and 0.08 μg per g of IE white. We applied successfully the method for the determination of I⁻ in commercial IEs.

In a qualitative test for urine protein by a test paper based on a protein error of tetrabromophenol blue, how the color development changes was examined by experiments and calculations when a pH change in the reaction mixture occurs in immersing a test paper in a urine sample whose pH may vary approximately from as low as 4.6 to as high as 7.8. In an experiment using bromophenol blue, the color development increased due to an increase in the pH of the reaction mixture, and the relative color intensity was closely associated with the magnitude of the pH change and the concentrations of the dye, buffer and protein. That is, even if the pH change by urine samples was equal, the relative color intensity differed with the concentrations of the dye, buffer and protein. It increased with an increase in the dye and buffer concentrations, and with a decrease in the protein concentration. These experimental results coincided well with those obtained by the calculation. It is important that the detection of a urine sample with a low protein concentration is carried out by using a test paper in which the dye concentration is low in order to suppress a false-positive result.

For the purpose of marine environmental radioactivity monitoring, stable Cs and ¹³⁷Cs concentrations were obtained from 214 marbled flounder (Pleuronectes yokohamae) samples collected from off the coast of Ibaraki prefecture in Japan in 2005 and 2006. Prior to the investigation, an analytical method for the determination of Cs in muscle of marbled flounder samples by inductively coupled plasma mass spectrometry (ICP-MS) was seriously considered from the view point of sample preparation (wet way) to a Cs measurement. Since major problems in determining Cs by the ICP-MS is the interference of matrix materials and molecular ions on Cs peak area (m/z 133), a known amount of In (m/z 115) was added to the sample solutions as an internal standard. To check the accuracy of the determination, duplication analysis and standard reference materials were used. Analytical results of Cs in muscles samples by ICP-MS agreed well with duplicated samples, and standard reference materials. The standard length and body weight were obtained from a total of 214 flounder samples. The stable Cs, stable K and ¹³⁷Cs concentrations in muscle were determined by ICP-MS, flame photometry and radiochemical analysis, respectively. The mean standard length correlates closely with the mean body weight. The stable Cs concentration was in proportion to the body weight, also, the ¹³⁷Cs concentration correlated closely with the stable Cs concentration in muscle. On the other hand, a stable K concentration was found to be uniform, and unrelated with ¹³⁷Cs and stable Cs concentrations. The specific activities, the ratio of ¹³⁷Cs/stable Cs in muscle, was found to be 5.5〜6.7 with an average of 6.2±0.35 (SD) among five different size groups of the standard length of marbled flounder samples. From these results, ICP-MS provided useful tools for the determination of a trace amount of Cs in muscle samples, combined with wet way pretreatment techniques. In addition, marbled flounder proved to be a useful species for comparing the radioactivity of fishes in coastal seas around Japan with each other in the environmental radioactivity monitoring program.