Dynamic sequential extraction procedure using a four-channel circulating flow system for extracting Hg from soil samples.

Mercury (Hg) is harmful to the human body. Its physical properties and toxicity differ greatly depending on its chemical form. The quantification of soluble Hg in soils or sediments is crucial for preventing further environmental contamination by Hg sources such as products, processes, and storage. In this study, the risk of leachable Hg that release from soil to the hydrosphere was evaluated by the sequential extraction procedure (SEP), a speciation method of a targeted element based on the solubility of its various compounds. The SEP, which consists of a four-channel circulating flow system (FCFS), was developed to reduce the time and amount of liquid required for SEP of leachable Hg in the Bloom method, which is a conventional SEP for Hg in a solid sample. The SEP with FCFS was optimized by considering the impact of extractant volume, circulation extraction time, and flushing of the extraction line. In the three-step (Fraction 1-3) sequential extraction of leachable Hg in soil samples, the optimized SEP with FCFS required 45 mL of extractant and 2.5 h, while the common batch SEP required 75 mL of extractant and 49 h. Furthermore, the combination of the SEP with FCFS for the leachable forms (Fraction 1-3) and the batch method for the insoluble forms (Fraction 4-5) was applied to the five-step SEP of Hg from CRM-JSAC0403. The sum of Hg concentrations that were classified into five fractions was in good agreement with that obtained from the batch method for all extraction, indicating that there are no significant differences in the concentrations extracted from the four channels.

Simple mercury determination using an enclosed quartz cell with cold vapour-atomic absorption spectrometry.

A simple method for determining total inorganic mercury (Hg) in solution using an enclosed quartz cell applying cold vapour-atomic absorption spectrometry (CV-AAS) can reduce sample volume, reductant, and cost compared with those of official methods. The Hg determination under the optimised conditions achieves precision similar to that of conventional CV-AAS.

Optical Etching to Pattern Microstructures on Plastics by Vacuum Ultraviolet Light.

We proposed and demonstrated an optical dry etching method for transferring a pattern on a photomask to a surface of plastics by decomposing the irradiated area using the high energy of vacuum ultraviolet light (VUV) at room temperature and pressure. Two kinds of wavelengths of 160 nm and 172 nm were used as the vacuum ultraviolet light, and the patterning performances for polymethyl methacrylate (PMMA) and polycarbonate (PC) were compared. As a result, it was revealed that proportional relationships were obtained between the etching rate and the irradiation dose for both wavelengths, and the cross-sectional profiles were anisotropic. In addition, both PMMA and PC were etched at a wavelength of 160 nm, whereas PC could not be etched at a wavelength of 172 nm, suggesting that it correlates with the bond dissociation energies of the molecular bonds of the materials and the energies of the photons. Furthermore, by combining this method with the optical bonding method that we had previously developed to bond surfaces irradiated with VUV, we have demonstrated a method for fabricating microfluidic devices by irradiating only with VUV. This paper shows that this technique is a new microfabrication method suitable for simple and mass production of plastic materials.