Vol. 59 No. 4
The definition, property, application fields and purification facilities of ultra-pure water are first overviewed based on recent achievements in the technologies of water recycling and reductions in chemical consumption. Then, an ion-adsorption filter for removing ppt levels of ionic impurities from ultra-pure water, and functionalized ultra-pure water for precision cleaning in the fields of semiconductor and flat-panel displays are described as recent achievements in ultra-pure water technology.
A spectrophotometric flow injection method is proposed for the determination of formaldehyde (HCHO) in wastewater. The condensation of HCHO with hydroxylamine sulfate produces formaldoxime. In this reaction hydroxylamine decreases in proportion to the concentration of HCHO. Residual hydroxylamine reduces the iron(III)-1,10-phenanthroline (phen) complex to a red iron(II)-phen complex (λmax = 510 nm). Therefore, the decrease in hydroxylamine can be monitored by measuring the decrease in the absorbance at 510 nm. Consequently, HCHO can be determined indirectly. A standard/sample solution containing HCHO is injected into a water carrier solution so that a negative FIA peak can be obtained. Under the optimized experimental conditions, HCHO in an aqueous solution was determined over the concentration range of 0.25〜1.0 mg L−1. The limit of detection (S/N = 3) was 20 μg L−1 HCHO. The relative standard deviation values (n = 4) were 2.03, 0.80 and 0.27% for the responses at 0.25, 0.50 and 1.00 mg L−1. The sampling throughput was 15 samples h−1. Analytical results for 5 wastewater samples were obtained with no significant difference between the proposed method and an official method.
A calibrational relation between the emission intensity ratio and the atomic ratio was investigated in a Ni–Zn binary alloy system when a low-pressure argon laser-induced plasma was employed as the excitation source. The sampling amount of the alloy samples was drastically reduced compared to a pure Zn sample, indicating that Zn atoms became less evaporated due to alloying with Ni. The Ni–Zn binary alloy has several metallurgical phases depending on the chemical composition : α-phase (Ni solid solution with Zn), β-phase (NiZn intermetallic compound), and γ-phase (NiZn3 intermetallic compound), which could each suppress the evaporation of Zn atoms. Calibration curves for several pairs of Ni and Zn emission lines did not follow a linear relationship, even when several measuring conditions such as the gate width and the delay time were varied. The reason for this would be that the evaporation behavior of Zn is different among the alloy phases and their metallurgical structures in the Ni–Zn alloy system.
A method of in-situ transmission X-ray diffraction (XRD) under a hydrothermal condition has been developed using a newly designed autoclave cell in combination with high-energy X-rays from a synchrotron-radiation source. The autoclave cell has X-ray windows made of thin beryllium foil, which enables one to obtain XRD patterns without any interference signals from the window materials. This method was applied to an in-situ investigation of a tobermorite formation reaction. It has been revealed that there are at least two pathways for tobermorite formation with different intermediate materials, which occur sequentially rather than simultaneously.
The factors influencing the accuracy of the concentration for a volatile organic compound (VOC) standard solution in its preparation procedure were evaluated by designing experiments using an orthogonal arrays table (L18). The factors tested were A : kinds of solvent, B : air-space volume in vessel, C : period after picking up bottles of raw material from freezer and D : storage temperature of stock solution. Eighteen kinds of trans-1,2-dichloroethylene solutions that had different sets of the four factors were prepared and measured by gas chromatography. The results showed that the air-space volume in the preparation vessels had the largest influence on the accuracy for a concentration of the VOC standard solution. Three 1000 mg L−1 1,1-dichloroethylene solutions were prepared from stock solutions (100000 mg L−1), which had different air-space volumes (9%, 39%, 70%) in the vessels, respectively. The measured concentrations of the three 1000 mg L−1 solutions decreased along with an increase in the air-space volume for the stock solution. These results were in good agreement with the calculated values based on Raoult’s law using the vapor pressures of 1,1-dichloroethylene and methanol. At a 9% air-space volume of the vessel, 0.070% of 1,1-dichloroethylene and 0.013% of methanol were calculated to be vaporized. When the vapor pressure of solute was higher than that of the solvent, a larger influence on the concentration of solute was expected. When solutions were prepared with a 5% or less air-space volume of the vessel, however, the influence on the accuracy of the concentration became a minimum (less than 0.01%). Moreover, the air-space volume of the sample vials for GC measurements was also found to influence the accuracy of the concentrations of VOC compounds of higher vapor pressure.
The determination of 9 corticosteroids in environment samples by a liquid chromatography/mass spectrometry (LC/MS) was established, and was applied to river water. After river-water samples were filtered through a glass microfiber filter, GF/B, these filtrates were passed through a solid-phase extraction cartridge and extracted corticosteroids. Extraction solutions were concentrated and re-fused by acetonitrile, and the resulting extracts were directly injected into the LC/MS system. The mobile phase used was acetonitrile - ammonium acetate buffer (pH 5.0) for gradient elution and detected by MS. Under the optimum analytical conditions, the correlation coefficients of calibration curves were more than 0.9971, and the limits of detection (S/N = 3) were in the range of 0.7〜2.4 ng/L. The recoveries of corticosteroids from river water spiked at 10 ng/L were 56.2〜110%. This method was satisfactorily used for the determination of corticosteroids in river-water samples.
An estimation of the chemical composition of cement in hardened mortar by an electron probe microanalyzer was studied. Mortar was prepared with ordinary Portland cement in accordance with JIS R 5201. Two square areas of 400 micrometer by 400 micrometer in the mortar were subjected to mapping analysis to quantify nine major elements of cement. The size of a pixel for analysis was fixed at 1 micrometer by 1 micrometer. Quantified values of each element (as oxide) in each pixel were converted by treating their sum as 97% and retaining their relative ratios. The average of the converted composition for many pixels was caluculated, and it was regarded as the estimated composition of cement. The average for all 160000 pixels was higher in SiO2 than the actual chemical composition of cement. Silica sand uesd as an aggregate was considered to be the reason for the high SiO2 in the estimated composition. It was clarified that the exclusion of pixels correspond to aggregate was important for a proper estimation. The discrimination of pixels correspond to cement and aggregate and exclusion of pixels correspond to aggregate based on value of SiO2 and CaO made it possible to obtain the estimated composition closer to the actual one compared to the estimated composition with all pixels.
ISO 24293 : 2009 describes a new international standard method for the determination of 13 individual 4-nonylphenol (4-NP) isomers in non-filtered samples of drinking water, wastewater, ground water and surface water using solid-phase extraction and gas chromatography/mass spectrometry. To validate this method, 17 laboratories from 3 different countries participated in an interlaboratory trial to determine its performance characteristics. The interlaboratory trial was evaluated according to ISO 5725-2, and included four triplicate non-filtered water samples : surface river water with low (RW1) and high (RW2) concentrations of 4-NP standard spiking and wastewater with low (WW3) and high (WW4) concentrations of 4-NP standard spiking. The repeatability variation coefficients (within-laboratory precision) varied for all isomers, ranging from 4.4% to 21.6%. The reproducibility variation coefficients (between-laboratory precision) were found to be 24.9 ± 6.4% for RW1, 30.6 ± 10.7% for RW2, 63.3 ± 34.6% for WW3, and 36.6 ± 13.5% for WW4. Proficiency testing concerning the ability of analytical laboratories was performed based on ISO/IEC Guide 43-1, “Proficiency testing by interlaboratory comparisons”. The laboratories were evaluated using z scores based on a robust method ; 8 to 13 laboratories (71% to 92%) were estimated to be “satisfactory (| z | ≦2)”, 0 to 1 laboratories (0% to 10%) as “questionable (2＜ | z | ＜3)”, 1 to 3 laboratories (7.7% to 23%) as “unsatisfactory (| z | ≧3)” for all water samples tested.
It was a problem that soil organic matter overlapped on quantitative analysis for nonvolatile oils in polluted soil. A selective quantitative analysis for oil using TLC/FID was attempted for the purpose of a properly/quantitative determination of oil only in polluted soil. Soil organic matter as the interfering substance of the analysis were fractionated with the development of TLC. Moreover, the development distance of TLC was extended so as to divide up the measurement with FID in order to improve of the division between the soil organic matter and the oils. Accordingly, the types of soil organic matter separated from the oils, and the influence for the quantitative analysis of oils in polluted soil was successfully reduced.
The concentrations of chlorate (ClO3−) and bromate (BrO3−), generated from sodium hypochlorite (NaClO) used as bactericidal agents in a swimming pool collected in Yokohama, were higher than environmental quality standards for water pollution in Japan. In this study, we investigated the effect of chlorate and bromate on the potassium permanganate consumed, KMnO4 in the swimming pool. It was found that potassium permanganate consumed decreased upon the addition of chlorate and bromate to tap and swimming-pool water, while the total organic carbon (TOC) concentration was not affected. The effect of bromate on the potassium permanganate consumed was about 18-times higher than the effect of chlorate, although the mechanism was not cleared. Our results suggested that careful attention is required concerning sanitation of a swimming pool, even though the potassium permanganate consumed as organic pollutants was low.