BUNSEKI KAGAKU Abstracts

The total cyanide contents in the environment and wastewater are strictly regulated, because cyanide compounds are very toxic substances. Generally, total cyanide is determined by the JIS method in Japan. However, many reports have been issued that cyanide ion had been detected in wastewater and waste discharged from factories that do not handle any cyanide compounds. These examples included printed circuit board plating, non-cyanide zinc plating, photographic processing waste solutions, electro-deposited paints, aluminum processing waste, etc.. It was theorized that hydrogen cyanide was formed by the reaction of organic compounds, such as EDTA and nitrogen oxides, during the distillation process or under high-temperature conditions. Recently, free cyanide ion was detected in an electro-less nickel plating bath at room temperature by alkaline fixation. The total cyanide was detected in an absorbed solution of the heavy oil combustion gas and in the effluent of a coal-fired station. This paper describes the cause of cyanide formation based on these examples. In addition, a pretreatment method of total cyanide by JIS was improved, and a new separation procedure for the total cyanide was proposed.

The photometric detection-FIA of L-ascrbic acid (L-H₂A) in colored and turbid aqueous solution is often difficult due to light-absorbing by coloring matter and light-scattering by an insoluble material. A FIA method has been developed for the determination of L-H₂A at the 10⁻⁶ M level in colored and turbid samples. It is based on the reaction of L-H₂A with iodine, and then a photometric measurement of the absorbance for the residual iodine as triiodide at 350 nm. The proposed method consists of two procedures : procedure I can measure the sum peak-height of the both absorbance-decrease (negative-peak) from the background as a result of iodine consumption with L-H₂A and absorbance increase (positive-peak) by the colored and insoluble elements in the sample ; procedure II can measure a positive-peak of the absorbance-increase by the matrix. The detector response corresponding to L-H₂A in the sample was estimated by a correction of the sum peak-height obtained in procedure I with the peak-height of the absorbance-increase in procedure II. The calibration graph was linear over the range 2.7×10⁻⁸ M〜4.5×10⁻⁶ M (4.8〜790 ppb) L-H₂A. The proposed method was successfully applied to the determination of L-H₂A in colored and turbid soft-drink samples without any tedious pretreatment, and the obtained results were compared with those by our previous spectrophotometric method. This method is approximately 50-fold more sensitive than a FIA method of Hernandez-Mendez et al. using iodate as an oxidation reagent of L-H₂A. Good recoveries of L-H₂A added to the sample solutions were achieved by using the proposed method.

Dioxins in six river and three marine sediments at Nagoya City were determined, and an estimation of their sources was performed. The average concentration was found to be from 230 pg g⁻¹ to 59×10³ pg g⁻¹, and the average TEQ concentration was from 0.34 to 56 pg-TEQ g⁻¹. In the distribution of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), the percentage of OCDD was especially high (35〜72％), and the order of HpCDDs was (9〜13％), TeCDFs (3〜11％) and TeCDDs (5〜9％). From a factor analysis, it was considered that three components, such as combustion, commercial PCB and chlorinated pesticides (PCP and CNP), were sources of dioxins in the sediments. Furthermore, the contributions of the sources were estimated from multiple regression analysis. The percentages of TEQ contribution from combustion, commercial PCB, and pesticides were 61〜90％, 6〜39％ and trace level, respectively.

In order to elucidate the mechanism of water purification in tideland, we measured the concentration of elements and chemical states of iron in tideland and canal sediments. Sediment samples were collected from 2 locations : the Yatsu Tideland, and the Shibaura Canal, which wasn’t considered to work as a purification system. The vertical distributions of 30 elements for each sample were determined by instrumental neutron activation analysis (INAA) and neutron-induced prompt γ-ray analysis (PGA). The chemical states of iron in the sediments were measured by ⁵⁷Fe Mössbauer spectroscopy. In the distribution of iron components, pyrite (FeS₂) was found in almost all samples, and its maximum abundance distribution was found in the middle layer of sediments. In the Yatsu tideland, the vertical distribution of paramagnetic high-spin Fe^3＋ and paramagnetic high-spin Fe^2＋ in all sediments was distributed complementarily to pyrite. However, this phenomenon was incompatible in the Shibaura canal, where pyrite was distributed complementarily to paramagnetic high-spin Fe^3＋ and/or paramagnetic high-spin Fe^2＋. This suggests that some amounts of the Fe^3＋, Fe^2＋, or both of them, were consumed for pyrite formation in the middle of the layer. Concerning the elemental distribution, the concentration of Cr was about 50〜60 ppm, and Cd was under the detection limit (＜0.5 ppm) in all sediment samples analyzed for the Yatsu tideland. On the other hand, in the Shibaura canal, Cd and Cr showed higher concentrations, and were condensed in the middle layer of the sediment. Their distribution was related to that of sulfide or hydroxide. This fact is regarded as the “water purification system” in the Shibaura canal. The reaction of sulfur and metals is considered to be the key point of the water purification system.

Various contaminants might be frequently detected in high-performance liquid chromatography/mass spectrometry (LC/MS) experiments. This makes highly accurate qualitative and quantitative analyses of LC/MS difficult. It is necessary to know the identification and origin of the contaminants to prevent them from being mixed. In the present work, we paid attention to any contaminants eluted from vials, septa and syringe filters used for an automatic sampling device and filtration preparation in LC/MS experiments. Some contaminants were identified by LC/MS and MS/MS analysis. In addition, we could specify the contaminant source.

For a highly sensitive analysis of formaldehyde and acetaldehyde in water, a degradation of formaldehyde and acetaldehyde in blank water by ⁶⁰Co γ-ray irradiation was demonstrated. Formaldehyde and acetaldehyde in water were evaluated by using a large-volume injection/column switching/high pressure gradient HPLC system coupled with 2,4-dinitrophenylhydrazine derivatization. By γ-ray irradiation, formaldehyde was decomposed to formic acid, and the resulting formic acid was furthermore decomposed. Acetaldehyde also oxidized to acetic acid upon exposure to γ-rays. In the early stage of γ-ray irradiation for Milli-Q water, the formaldehyde and acetaldehyde in Milli-Q water increased, and many unknown peaks appeared in HPLC chromatograms. The formaldehyde, acetaldehyde and unknown species formed upon γ-ray irradiation may be derived from trace organic mater contained in Milli-Q water. Acetaldehyde and unknown peaks disappeared upon further γ-ray irradiation, and the formaldehyde peak was also diminished. In this report, purification of the DNPH derivatization reagent is also mentioned.

The potassium, calcium, magnesium zinc, manganese, copper and phosphorus contents of 6 milled rice samples were measured by the ICP-OES method in cooperation with 5〜7 laboratories in Japan. According to the protocol that determined the measuring conditions etc., 6 milled blind replicate rice samples were measured, and single result of the contents (mg/kg, as received) of seven elements were reported. The data from which the maximum of one laboratory’s data were removed by Cochran and Grubbs outlier test, and an analysis of the variance were carried out. The range of analysis values for six samples calculated from collaborative trial was as follows, RSD_r (the relative standard deviation of repeatability), RSD_R (the relative standard deviation of reproductibity) and HorRat values of potassium were 1.03〜1.86％, 5.08〜6.93％ and 0.89〜1.13, respectively ; those of magnesium were 1.87〜6.14％, 7.02〜9.99％ and 1.06〜1.44, respectively ; and those of calcium were 1.27〜5.93％, 3.40〜6.46％ and 0.38〜0.70, respectively. The HorRat values of zinc, manganese, copper and phosphorus were 0.32〜0.54, 0.30〜0.65, 0.41〜1.49 and 1.18〜1.43, respectively. The HorRat values of all the elements (potassium, calcium, magnesium, zinc, manganese, phosphorus and copper) being lower than 1.5, showed that the measured results of this collaborative trial were satisfying. Moreover, the results for RSD_R and RSD_r of this trial showed the validity of the measuring method of the inorganic element content in milled rice by the ICP-OES method.