Certification of butyltins and phenyltins in marine sediment certified reference material by species-specific isotope-dilution mass spectrometric analysis using synthesized <Superscript>118</Superscript>Sn-enriched organotin compounds

A new marine sediment certified reference material, NMIJ CRM 7306-a, for butyltin and phenyltin analysis has been prepared and certified by the National Metrological Institute of Japan at the National Institute of Advanced Industrial Science and Technology (NMIJ/AIST). Candidate sediment material was collected at a bay near industrial activity in Japan. After air-drying, sieving, and mixing the material was sterilized with γ-ray irradiation. The material was re-mixed and packaged into 250 glass bottles (15 g each) and these were stored in a freezer at −30 °C. Certification was performed by use of three different types of species-specific isotope-dilution mass spectrometry (SSID–MS)—SSID–GC–ICP–MS, SSID–GC–MS, and SSID–LC–ICP–MS, with ¹¹⁸Sn-enriched organotin compounds synthesized from ¹¹⁸Sn-enriched metal used as a spike. The ¹¹⁸Sn-enriched mono-butyltin (MBT), dibutyltin (DBT), and tributyltin (TBT) were synthesized as a mixture whereas the ¹¹⁸Sn-enriched di-phenyltin (DPhT) and triphenyltin (TPhT) were synthesized individually. Four different extraction methods, mechanical shaking, ultrasonic, microwave-assisted, and pressurized liquid extraction, were adopted to avoid possible analytical bias caused by non-quantitative extraction and degradation or inter-conversion of analytes in sample preparations. Tropolone was used as chelating agent in all the extraction methods. Certified values are given for TBT 44±3 μg kg⁻¹ as Sn, DBT 51 ± 2 μg kg⁻¹ as Sn, MBT 67 ± 3 μg kg⁻¹ as Sn, TPhT 6.9 ± 1.2 μg kg⁻¹ as Sn, and DPhT 3.4 ± 1.2 μg kg⁻¹ as Sn. These levels are lower than in other sediment CRMs currently available for analysis of organotin compounds.     

Certified reference material for quantification of polycyclic aromatic hydrocarbons in sediment from the National Metrology Institute of Japan

The National Metrology Institute of Japan has issued a certified reference material (CRM) of freshwater lake sediment for polycyclic aromatic hydrocarbon (PAHs) analyses. The certification used three extraction techniques: pressurized liquid extraction (PLE) with toluene, PLE with dichloromethane/ethyl acetate (1:1 by volume), and alkaline extraction (1 M KOH in methanol) in combination with microwave-assisted extraction. Both gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/dopant-assisted atmospheric pressure photoionization/MS (LC/DA-APPI/MS) analyses were used. Certified values are provided for 18 PAHs at 1–25 μg kg⁻¹ except for perylene (2.08 × 10³ μg kg⁻¹), and information values are provided for two. Since the values of PAHs in the CRM are much lower than those in other CRMs and are comparable to those found at sites with little human influence, the CRM is suitable for PAH monitoring in sediment and soil samples.     

Determination of phosphorus using capillary electrophoresis and micro-high-performance liquid chromatography hyphenated with inductively coupled plasma mass spectrometry for the quantification of nucleotides

We performed the quantification of phosphorus in deoxynucleotides using capillary electrophoresis (CE) and micro-HPLC (μHPLC) hyphenated with inductively coupled plasma mass spectrometry (ICP-MS). DNA and its component units have conventionally been determined by photometry; however, more selective and sensitive methods are needed for small biological samples. CE and μHPLC offer the advantages of good separation and small consumption of samples, and ICP-MS is a highly sensitive technique for the determination of a chemical element. Therefore, we have developed an interface device for combining CE and μHPLC with ICP-MS for quantifying nucleotides based on phosphorus content. The interface utilizes 4.5 μL/min for nebulizing and effective introduction of the sample into ICP. The samples of nucleotides and free phosphoric acid were well separated in the CE–ICP-MS measurement, and the calibration curves (1–100 μg/mL) of the nucleotides showed a linear (R² > 0.999) increase in intensity. Similarly, the samples of nucleotides were baseline separated using μHPLC–ICP-MS, and the calibration curves of the nucleotides were linear (R² > 0.998). The detection limits of these species and phosphorus in nucleotides using CE–ICP-MS and μHPLC–ICP-MS were 0.77–6.5 ng/mL and 4.0–6.5 ng/mL, respectively. These values were about one or two orders lower than those in a previous report. The sample volumes of these experiments were calculated to be about 10 nL and 50 nL per analysis. Therefore, these analytical methods have the potential to be useful for the determination of biological samples, such as DNA and RNA molecules.     

Synthesis and properties of azo dye aligning layers for liquid crystal cells

The synthesis and properties of azo dyes that can be used for photoaligning liquid crystals (LCs) have been investigated. The structures and the synthetic procedure for the azo dyes are presented. The photoaligning of azo dyes takes place purely due to the reorientation of the molecular absorption oscillators perpendicular to the UV light polarization. The qualitative model for the phenomenon in terms of the rotational diffusion of the azo dye molecules in the field of the polarized light is discussed. The order parameters S = -0.4 (80% of the maximum absolute value S_m = -0.5) were measured from the polarized absorption spectra at the wavelength 372 nm. A temperature stable pretilt angle of 5.3° was obtained by a two-step exposure of the azo dye film using normally incident polarized light followed by oblique non-polarized light. The azimuthal anchoring energy of the photoaligned substrate was A_ϕ ≈10^-4 J m^-2, which is the same as the anchoring of the rubbed polyimide (PI) layer. The voltage holding ratio value of a photoaligned LC cell was found to be even higher than for a rubbed PI layer, which enables the applications of azo dyes as aligning layers in active matrix liquid crystal displays. The thermal stability of the photoaligned azo dye layers is sufficiently high, but UV stability has to be improved, e.g. by polymerization. A new LCD aligning technology based on polymerized azo dye layers is envisaged.     

Unconventional anomalous hall effect in the metallic triangular-lattice magnet PdCrO₂

We experimentally reveal an unconventional anomalous Hall effect (UAHE) in a quasi-two-dimensional triangular-lattice antiferromagnet PdCrO?. Using high quality single crystals of PdCrO?, we found that the Hall resistivity ρ(xy) deviates from the conventional behavior below T*?20 K, noticeably lower than T(N)=37.5 K, at which Cr3+ (S=3/2) spins order in a 120° structure. In view of the theoretical expectation that the spin chirality cancels out in the simplest 120° spin structure, we discuss required conditions for the emergence of UAHE within Berry-phase mechanisms.