BUNSEKI KAGAKU Abstracts

The analytical conditions of a double-focusing sector field ICP-MS were optimized to determine the Pb isotope ratios accurately in bullet samples. The following three different types of mass bias corrections were examined to obtain accurate isotope ratios: i) an external correction with a NIST SRM981 standard, (ii) an internal correction with Tl as an internal standard (NIST SRM997), and (iii) both (i) and (ii). Method (i) gave the best result under the present experimental conditions. The relative standard deviations of lead isotopic ratios (²⁰⁸Pb/²⁰⁶Pb, ²⁰⁷Pb/²⁰⁶Pb) for bullet samples (N = 28) were as small as 0.034%, demonstrating that a high-precision lead isotope analysis was possible under almost comparable precision with a multiple collector sector field ICP-MS. It was indicated that this precision is suitable for distinguishing the origin of bullet samples; 87% of handgun bullet samples (N = 15) and 69% of rifle bullet samples (N = 13) were successfully discriminated from each other. The introduction of information concerning the trace element concentration obtained by the same ICP-MS into the lead isotope ratios will afford an almost complete discrimination of the bullet samples.

Nitrophenols (NPs), having effects on human health, are produced in the atmosphere via several pathways. However, the behavior details of atmospheric NPs are not well understood. In this work, daily variations of NPs were investigated by repeating 2-h collection using silica-gel columns followed by HPLC/MS analysis. The collection method was optimized and large-volume injection and in-line preconcentration was automated for the HPLC analysis. The quantification limits by atmospheric-pressure chemical ionization mass analysis for each atmospheric NP ranged between 0.08 and 0.67 ng m⁻³ with a time resolution of 2 h. Clear daily variations were obtained by this method. Whereas NP concentrations were high around noon in the summer, they were maxima before midnight in the winter. This was likely due to a difference in the main mechanism for NP formations: mainly the OH radical and the NO₃ radical initiated the formation reaction in the summer and winter, respectively. In the winter, the total NP concentration was higher than that in the summer especially 2-nitrophenol which accounted for half of all NPs measured. On the contrary, formation of dinitrophenol from mononitrophenol seemed to proceed abundantly in the summer. Also, a seasonal variation was detected from rain water analysis and filter sampling. The concentrations and partition of NPs were different, alowing differences in the polarity and reactivity. It was considered that the NP concentrations changed dynamically in the atmosphere via secondary production, and reactions to disappear.

An inductively coupled plasma-time of flight mass spectrometry coupled with a gas-exchange device (GED-ICP-TOFMS), which could introduce ambient air directly into the ICP, was developed and applied to direct simultaneous multi-element analysis in tobacco smoke in this study. Even if the flow rate and the gas concentration of tobacco smoke as well as the element concentrations in tobacco smoke change due to variations of its burning condition with time and changing environment, GED-ICP-TOFMS is considered to be the real-time multi-element analytical method because ICP-TOFMS measures multi-elements simultaneously. Direct simultaneous multi-element analysis in tobacco smoke was performed by GED-ICP-TOFMS. Elements such as B, Rb, Cd, I, Tl and Pb were detected as peculiar ones in side-stream tobacco smoke. The same elements were also detected in main-stream tobacco smoke, different intensity ratios of elements were observed with respect to those in the side-stream smoke. The possibility to distinguish different tobaccos that can be commercially available could be revealed using the intensity ratios of elements in the side-stream tobacco smokes. The intensity ratios of elements in main-stream smoke showed different ratios compared to those in side-stream ones. The GED-ICP-TOFMS developed in this study is the first analytical method in the world using the GED made in Japan. It is expected to be a real-time, higly sensitive, direct and simultaneous multi-element analytical technique for gas samples as well as environment monitoring, which change dramatically and rapidly with time.

Metal complexes or chelators were covalently attached to the end of oligodeoxyribonucleotide (ODN) to prepare several ODN conjugates (probes). The sequences of the probes were designed so as to bind neighboring sites on the target. The interaction between functional metal complexes in the probes would generate a specific signal, depending on the sequence of the target serving as a template. The general concept of “DNA labeling by functional metal complexes” was demonstrated by the discrimination of the SNP (single nucleotide polymorphism) base and the recognition of a repetitive sequence. For the former system, a set of DNA conjugates, EDTA-modified and phen-modified ODN (phen = 1,10-phenanthroline), were prepared for the DNA-templated formation of luminescent lanthanide complexes [Ln: Tb(III) or Eu(III)]. When a ternary duplex consisting of the target and the two probes forms, EDTA and phen moieties of the probes face each other and are expected to function as dehydration/capturing units for lanthanide ion, respectively. The characteristic emissions of Tb(III) and Eu(III) ions were clearly observed only in the presence of a fully matched target. Their luminescence lifetimes were 1.26 and 1.34 ms for Tb(III) and Eu(III); they are long enough to be subjected to time-resolved luminescence measurements. Biallelic polymorphism in the thiopurine S-methyltransferase (TPMT) gene, wt/wt (G/G), mut/mut (C/C), and wt/mut (G/C), were distinguished as emissions in green [Tb(III)], red [Tb(III)], and yellow [Tb(III)+Eu(III)], respectively; the colors were identified even by the naked eye. The concept of the cooperative formation of luminescent lanthanide complexes could also be applied to the biomolecular sensor by the concomitant use of an aptamer and a stem-loop structured ODN caring EDTA and phen at its both ends. For the latter system, the [Ru(phen)₂(dppz)]²⁺ (dppz = dipyrido[3,2-a:2',3'-c]phenazine) complex was attached to the 5' end of the short ODN to form conjugates. The sequence is complementary to one unit of the repetitive sequence of human telomere. The complex expands the planar aromatic ring of dppz for an intercalation with the Ru(phen)₂ moiety remaining in a groove. The preference of the tethered [Ru(phen)₂(dppz)]²⁺ complex to the duplex structure should promote the binding of another probe to an adjacent site. That is, a cooperative behavior is expected for probe hybridization when it binds with repetitive sequences. The Δ-isomer of the probe showed a high cooperativity during the recognition of the human telomere repeats, while the Λ-isomer did not. By the addition of a target, the emission intensity of the Δ-isomer modified probe increased to be 6-times higher than before addition. This is the first example of a pair of diastereomeric fluorescent DNA probes that have been studied regarding their cooperativity during hybridization to adjacent sites.

A simplified high-performance determination method using a microplate has been developed as a microanalysis. This review was described with respect to high-sensitive microplate analysis using following reactions, device and method; an autocatalytic reaction with Na₂SO₃/H₂O₂, an oxidative reaction from porphyrinogen to porphyrin, microplate immobilized cationic water-soluble porphyrin and homogeneous liquid-liquid extraction. These proposed methods can analyze trace substance (e.g. metal ion, antigen, endocrine disruptor etc.) in small-volume samples. Furthermore, some visual analyses by counting the number of color changes on the microplate were developed. In conclusion, any method is useful and practical for microplate analysis.

For the titular siloxane-containing alicyclic tetracarboxylic dianhydrides derived from endo⁻ and/or exo⁻5–norbornene-2,3-dicarboxylic anhydride and α,ω-hydrosilyl-origo-dimethylsiloxane, Si–O stretching vibration was investigated. Single absorption was observed for the disiloxane-chain; in contrast, two absorptions were observed for the tri- or longer siloxane-chain. The wavenumber of the higher band showed a constant value; however, the wavenumber of the lower band decreased with the siloxane-chain length, and the intensity of absorption increased. In the trisiloxane and further siloxane-chain, two oxygen atoms bonding with the inner silicon atom have two vibrational modes, namely symmetric and asymmetric. The number of absorption is fixed by a combination of the two vibrational modes. From a quantum chemical calculation, the absorption of the higher wavenumber showed a symmetric vibrational mode; on the other hand, the lower wavenumber showed an asymmetric vibrational mode. In addition, the ratio of the asymmetric vibrational mode increased with the siloxane-chain length. Therefore, it seems reasonable that the absorption intensity of the lower wavenumber side increased with the siloxane-chain length.

Archaeological finds from ancient tombs provide very important information about the ancient world. Vermilion (mercury sulfide, HgS) has often been found in grave burialsites, which was used not only to preserve dead bodies, but also to represent the authority of the buried persons. It is considered that the origin of burial vermilion may reveal information about the culture, civilization, political status and so forth in an ancient society. To elucidate the origin of burial vermilion, we have been analyzing the lead isotope ratios in natural ore (cinnabar ore) samples from several mines (Japan: Nara, Mie and Tokushima prefectures. China: Guizhou, Hunan and Shaanxi) and burial vermilion from several ancient Japanese burial mounds built in the 2nd to 4th centuries for a comparison. For isotopic measurements of lead, we employed TIMS (thermal ionization mass spectrometry) and MC-ICP-MS (high-resolution ICP-MS equipped with a multi-collector). The lead isotopes in cinnabar ore exhibited clear local characteristics, and the origin of the cinnabar ore could be distinguished from the lead isotope compositions. Furthermore, it was deduced that three of the vermilion samples in ancient tombs built around the 4th century originated from the Kinki region, and that the vermilion sample from the Ohburo-minami remains originated from Hunan or Guizhou. For two samples (Nishidani and Tatetsuki ancient tombs), the origin was unclear. However, the lead isotope compositions imply that they may have originated from north-east China. The results of this study show that isotopic measurements of lead can be a powerful tool to distinguish the sources of vermilion from remains. We will additionally perform systematic isotopic analyses of lead for several cinnabar ore samples in order to establish a distribution map of lead isotopes, and also measure the lead isotopes for vermilion from other ancient tombs to determine the source of vermilion.

Eight kinds of catechins are well known because of their antioxidant activity and chemopreventive effects against cancers. The determination of eight kinds of catechins {GC: (−)-gallocatechin; EGC: (−)-epigallocatechin; C: (+)-catechin; EC: (−)-epicatechin; EGCg: (−)-epigallocatechin gallate; GCg: (−)-gallocatechin gallate; ECg: (−)-epicatechin gallate; CG: (−)-catechin gallate} in bottled green tea drinks by high-performance liquid chromatography (HPLC) with an ultraviolet detector (UV) on a cholesteryl group stationary phase column has been developed. This analytical method provides high linearity of the calibration curve as well as both repeatability and reproducibility. The correlation coefficient of the working curve of calibration were estimated to be from 0.9998 to 0.9987 for eight kinds of catechins in the concentration range from 5 mg L⁻¹ to 150 mg L⁻¹. The limits of detection (LOD) calculated on 3σ at 10 mg L⁻¹ were 0.39 mg L⁻¹ for GC, 0.74 mg L⁻¹ for EGC, 0.07 mg L⁻¹ for C, 0.33 mg L⁻¹ for EC, 0.28 mg L⁻¹ for EGCg, 0.35 mg L⁻¹ for GCg, 0.18 mg L⁻¹ for ECg, and 0.19 mg L⁻¹ for CG. The limits of quantification (LOQ) calculated on 10σ at 10 mg L⁻¹ were 1.29 mg L⁻¹ for GC, 2.48 mg L⁻¹ for EGC, 0.24 mg L⁻¹ for C, 1.09 mg L⁻¹ for EC, 0.94 mg L⁻¹ for EGCg, 1.17 mg L⁻¹ for GCg, 0.62 mg L⁻¹ for ECg, and 0.65 mg L⁻¹ for CG. Good results (the recoveries were 85.5–109.6% and the relative standard deviations were 2.5–4.9%) were obtained in recovery tests by using bottled green tea drinks. This proposed method could be successfully applied to the determination of eight kinds of catechins in bottled green tea drinks.

In this study, we determined the carbon stable isotope ratios of the extract (δ¹³C_Ex) and alcohol (δ¹³C_Alc) in commercially-supplied Mirin in order to confirm them as a potential index for verifying the raw-material origins. The δ¹³C_Alc values of the Mirin, to which brewing alcohol was added (−14.6 ± 4.0‰), are significantly higher than that of the Mirin, to which Shochu was added (−26.0 ± 1.7‰). The δ¹³C_Ex values of the Mirin are significantly higher by sugar addition (+sugar; −17.1 ± 3.3‰, −sugar; −26.1 ± 1.0‰). Old-style Mirin, which was made from rice, koji, and Shochu shows lower δ¹³C_Alc and δ¹³C_Ex values (δ¹³C_Alc; −25.8 ± 1.1‰, δ¹³C_Ex; −26.6 ± 0.9‰) than those of new-style Mirin, which includes brewing alcohol and sugar as raw materials (δ¹³C_Alc; −16.3 ± 0.8‰, δ¹³C_Ex; −19.8 ± 0.7‰). Mirin-like seasonings (fermentation seasoning and Mirin-type seasoning) and Akumochizake used like Mirin were also analyzed; their δ¹³C_Alc and δ¹³C_Ex showed higher values upon the addition of brewing alcohol and sugar, respectively. These results suggest that the δ¹³C_Alc and δ¹³C_Ex values in commercially supplied Mirin are useful for the confirmation of sugar, brewing alcohol, and Shochu addition as raw-material origins.