Simple and rapid quantification of chromium, arsenic, and selenium in bituminous coal samples using a desktop energy dispersive X-ray fluorescence analyzer.

In this study, the simple and rapid quantification of Cr, As, and Se in bituminous coal was achieved by energy dispersive X-ray fluorescence (EDXRF) spectrometry using pressed and powdered samples. The accuracy of the EDXRF method was improved by spectral processing optimization so the net intensity of the analytical X-ray line reflected the actual value. The EDXRF method provides results that are comparable to those obtained using traditional chemical analysis methods with two types of samples and it reduces the analysis time by 66% for pellet samples and 90% for powder samples.

Simplified Mercury Extraction from Coal Fly Ash for Quantification of Total Mercury by ELISA-based Immunoassay.

A simplified two-step mercury extraction procedure enabled the selective and reproducible mercury recovery from actual coal fly ash (CFA). The optimized extraction procedure involving conventional enzyme-linked immunosorbent assay (ELISA)-based immunoassay allowed the ultra-sensitive quantification of total mercury content in CFA. The total mercury content of 41 CFA samples were successfully determined using the above-mentioned method, and the results were in agreement with those obtained by standard instrumental analysis (thermal decomposition atomic absorption spectrometry) within a 15% coefficient of variation. Our method for total mercury quantification is not only simple but suitable for management of the mercury content at coal-fired electric power plants and landfill sites, which deal with large amounts of waste CFA.

Development of a novel non-contact and quick-response detector for boron in coal fly ash based on thermal neutron absorptiometry.

Coal fly ash (CFA), a by-product from coal-fired power plants, has many applications. However, there are concerns that the trace elements in CFA-based materials may contaminate groundwater. Therefore, many methods have been developed to rapidly measure these trace elements in CFA in order to management and/or screening their leachability. However, satisfactory methods to measure boron alone have not been reported. In this study, we developed an instrument for the non-contact analysis of boron in CFA samples. This simple instrument consisted of a sealed neutron source, a moderator, a proportional counter, and a signal processing device. The analysis method, based on thermal neutron absorptiometry, can rapidly measure the boron content within five minutes without pre-treatment. We applied the developed equipment to over 200 CFA samples, and excellent correlation was obtained between the proposed and traditional methods. These results indicated that the developed equipment is useful for managing and/or screening boron in CFA.

Development of microchip for rapid pretreatment of trichloroethylene and tetrachloroethylene volatilized from polluted soil.

In the field of environmental analysis, microchip technology has many attractive features and is expected to realize the miniaturization of analytical instruments allowing on-site and multipoint monitoring using this technology. We propose a new soil analytical system for detecting trichloroethylene (TCE) and tetrachloroethylene (PCE) using a microchip. The experimental conditions for the pretreatment microchip were optimized. Under the optimized conditions, the detection limits of TCE and PCE were 15 and 9 ppbv, and the determination limits of TCE and PCE were 62 and 72 ppbv, respectively.

Desorption/ionization on carbon mass spectrometry: study of amorphous-carbon property.

In this study, an amorphous carbon was proposed as a new ionization substrate for laser desorption/ionization (LDI) and its efficiency for soft laser ionization without any matrix molecules was focused on the soft laser ionization effect of the amorphous carbon substrate was compared with that of a stainless substrate by LDI and matrix-assisted laser desorption/ionization (MALDI) using a 266-nm irradiation laser. The result of the amorphous carbon substrate was indicated to have a soft ionization effect similar to the result of MALDI. In addition, from the experimental result achieved by soft laser ionization using not only 266-nm-wavelength but also 355-nm-wave length irradiation lasers, the amorphous carbon substrate had a high degree of generality for selecting a sample similarly to soft ionization. The same experimental condition was carried out for other amorphous carbon substrates with different surface roughnesses in order to clarify the ionization mechanism on the amorphous carbon substrates. From the results, it was suggested that factors besides the difference in surface roughness exist for laser ionization efficiency.

Effect of aspect ratio on chemical reactions on microchip.

Parallel two-phase laminar flow, which is formed when two solutions flow in microchannels, has been developed and has advanced unique research in the area of microchip analysis. In two-phase laminar flow, channel size has a significant effect on the efficiency of chemical reactions. However, the sizes of microchannels vary greatly in many studies. In this paper, we report on the effect of microchannel size on chemical reactions on a microchip. Aspect ratio is defined as the ratio of depth to width of a microchannel. Five microchips with different aspect ratios (from 0.50 to 2.00) were fabricated by mechanical machining. The reaction of nitrous acid and Saltzman reagent was carried out on these microchips and the absorbance was measured on-line in a capillary tube, which was attached to the outlet on the microchip. The results showed that the color reaction occurred more efficiently as the aspect ratio increased. This result is expected to be useful when determining the size of microchannels.

Integration of the cleanup process: pretreatment of polycyclic aromatic hydrocarbons from diesel exhaust particles on silica gel beads in a microchannel.

This paper presents an integrated microfluidic system that performs cleanup for polycyclic aromatic hydrocarbons (PAHs) from diesel exhaust particles on silica gel beads in a microchip. A column chromatography phase was constructed by filling the silica gel beads into a microchannel that had a dam structure 25 microm high. The height of the dam structure was determined according to the rate of the wet etching. This work on the cleanup of PAHs from diesel exhaust particles showed that the microchip-based system has the same performance as the conventional method on the solid phase extraction column and has some advantages, such as less reagent consumption and shorter pretreatment time, over the conventional method.

Direct analysis of diesel exhaust particles by fragmentation-free mass spectrometry using ion attachment mass spectrometry.

We analyzed diesel exhaust particles immediately by fragmentation-free mass spectrometry using ion attachment mass spectrometry (IA-MS). IA-MS can be used to measure labile organic compounds without any fragmentation. Ionization without fragmentation can be performed because a neutral molecule becomes an adduct ion by the attachment of Li(+) with a small amount of energy by the Coulomb force. A third-body gas, such as 100 Pa N(2), removes any excess energy of the adduct ion and makes it stable. The aim is to be able to measure the preprocessing of the sample promptly using this analysis. In a direct analysis of diesel exhaust particles using IA-MS, many compounds (including some unknown chemicals) were detected. In the mass spectrum consisting of the ion peaks of many compounds, it is possible that the source and load factor to the environment are considered as one index.

Specific dual beam fluorometry analysis of benzo[a]pyrene and benzo[k]fluoranthene in diesel exhaust particulate samples.

We developed a specific analysis method for benzo[a]pyrene (B[a]P) and benzo[k]fluoranthene (B[k]F) using dual beam fluorometry. B[a]P and B[k]F exhibited two specific fluorescence intensities (up to 10-fold) compared with 22 other polycyclic aromatic hydrocarbons (PAHs) at 370 nm excitation and 429 nm emission wavelengths, and similarly at 395 nm excitation and 429 nm emission wavelengths. The concentrations of these compounds in diesel exhaust particles were calculated from two calibration curves determined using a mixture of 24 PAH standards. The precision of this detection method was compared with that of conventional high-performance liquid chromatography/fluorescene detector (HPLC/FLD), and our method gave accurate values within the analytical standard deviations. The monitoring method developed in this study will enable more rapid and easier detection.

Development of a micro dual beam fluorometric detector specific for microchip analysis of benzo[a]pyrene and benzo[k]fluoranthene in diesel exhaust particulate samples.

We developed a device and some systems for detecting benzo[a]pyrene (B[a]P) and benzo[k]fluoranthene (B[k]F). The device uses a UV light-emitting diode that emits light with a wavelength of 370 nm and a violet laser diode that emits light with a wavelength of 395 nm as excitation light sources. The detection method is based on the following observation: characteristic fluorescence is emitted from both B[a]P and B[k]F, with intensities up to 10 times greater than those from 22 other polycyclic aromatic hydrocarbons (PAHs). The excitation and emission wavelengths for fluorescence from B[a]P and B[k]F are 370 and 429 nm, and 395 and 429 nm, respectively. Further, we calculated their concentrations in diesel exhaust particles by means of two calibration curves determined using a mixture of 24 PAHs. The detection limits of the proposed device with a microchip are 5.58 microg L(-1) for B[a]P and 6.03 microg L(-1) for B[k]F. We applied this method to analyze B[a]P or B[k]F contained in three types of diesel exhaust particles, and the results agreed well with those obtained by liquid chromatography.