We have developed a database of calibration curves of 172 agricultural chemicals for GC/MS target screening analysis using two instruments (GCMS-QP2010 Plus and JMS-Q1050GC). We compared the slopes of each calibration curve and the quantification values determined from the calibration curve of each agricultural chemical. The best repeatability was found for the calibration curves constructed using the internal standard of the nearest retention time for each agricultural chemical. Furthermore, maintaining the instrument sensitivity was found to be the most important factor for obtaining good repeatability. The quantification values in the lower limit of the calibration curves of each agricultural chemical were compared. The quantification errors were 5 times or lesser for almost all the agricultural chemicals when employing the database developed using the same instrument. Based on these results, we confirmed that the GC/MS target screening method was useful for analyzing many agricultural chemicals and evaluating the excess with respect to the target value of each agricultural chemical in drinking water. Variation in instrument sensitivity is the main factor influencing the quantification error, and maintaining the detection sensitivity of the instrument is important when applying the target screening method to drinking water samples.

We analyzed 169 agricultural chemicals in raw and drinking water samples by target screening analysis using gas chromatograph-mass spectrometer (GC-MS). To verify the precision of the analysis, we analyzed the same samples using the official method of Japan. Because the ratios of the quantitative values obtained by target screening analysis and the official method were 0.14–2.8, this GC-MS-based target screening method was very useful for simultaneously monitoring a large number of agricultural chemicals and selecting chemicals for routine analysis. The quantitative values of some agricultural chemicals were not in good agreement when the GC-MS instrument was tainted with some matrices and when the detector performance deteriorated. This suggests that the GC-MS conditions are important for target screening analysis. We reanalyzed the data obtained by retrospective analysis and, identified and quantified two new compounds. Therefore, this target screening analysis could be used as a tool to identify unknown compounds.

We conducted a survey of the raw and finished water from 10 water purification plants in the Osaka Prefecture for the presence of ipfencarbazone, a herbicide. Solid-phase extraction-liquid chromatography-tandem mass spectrometry was used as the analytical method for ipfencarbazone detection. Ipfencarbazone was detected in raw water in the range of 0.0013–0.14 µg/L from 6 plants in summer and 0.00077–0.0020 µg/L from 4 plants in winter. In finished water, ipfencarbazone was detected in the range of 0.00066–0.086 µg/L from 5 plants in summer and 0.0014–0.0015 µg/L from 2 plants in winter. The detected ipfencarbazone concentration was compared with the target value (2 µg/L) set by the Ministry of Health, Labour and Welfare. The concentration in none of the samples exceeded the target value. The removal ratio was calculated from the ipfencarbazone concentrations in raw and finished water from each water purification plant. It was evident that ipfencarbazone could be effectively removed by advanced water purification treatment.

We have developed a target screening method based on quadrupole LC-MS/MS using the triggered MRM mode for the rapid and comprehensive detection of pesticides in drinking water. Among the 201 types of pesticides and metabolites, 91 types had a lower limit of quantification of 5 ng/L, and 46 types had a lower limit of quantification of 10 ng/L. In addition, we conducted an additional recovery test (100 ng/L; n＝5 parallel test, 5 times) in drinking water within 41 days after creating the database for screening analysis. The accuracy was found to lie between 70％ and 130％ for 164 types of pesticides and metabolites. The purity of 170 types of pesticides and metabolites, out of the 171 types, was in the range of 50–200％, which was originally set in this study as development target value of the screening method. The parallel precision was less than 30％ for all the 171 types of pesticides, and the indoor precision was less than 35％ for 170 of the 171 types of pesticides. The validation results suggest that this screening method can be effectively employed for drinking water.

The surfactants included in the PRTR system were detected using the notified analytical method for nonionic surfactants in tap water. False positive results were obtained when N,N-dimethyldodecylamine-N-oxide, an amphoteric surfactant, and sodium polyoxyethylene dodecyl ether sulfate, an anionic surfactant, were present in tap water. To clarify the behavior of various surfactants, except nonionic surfactants, in solid-phase extraction, different elution solvents were investigated. The total recoveries of various surfactants in the toluene and methanol fractions ranged from 60％ to 120％. Simultaneous solid-phase extraction-LC/MS was validated for all the surfactants using methanol as the elution solvent. For various surfactants, except for nonionic surfactants and anionic surfactants, the accuracy (recovery rates) and repeatability of analysis satisfied the criteria in the guideline for the validation of the testing method for drinking water provided by the Ministry of Health, Labour and Welfare, Japan. Thus, this screening method can be useful for determining the presence of various surfactants.

In this study, to develop a method for detecting phenols included in the Japanese drinking water quality standards, without using solid-phase extraction, a direct injection method based on liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) using dansyl chloride (DNS-Cl) derivatization was examined. We developed a test method by adding an internal standard solution, carbonate buffer containing phosphoric acid, and DNS-Cl solution to sample water, derivatizing it at a reaction temperature of 60°C, and subjecting it to LC/MS/MS. To evaluate the validity of our method, a spike and recovery test was conducted using tap water dechlorinated by sodium ascorbate and dechlorinated tap water containing copper sulfate and phosphoric acid for sample preservation. The results of the recovery test indicated that two factors, namely the accuracy and repeatability of the calibration curve and the accuracy, repeatability, and intermediate precision of the recovery test, satisfied the Japanese validation guidelines on drinking water analysis. Thus, this method can be useful for detecting phenols in drinking water.

A mechanism of decolorization of model colored wastewater by photo-Fenton process coupled with a carbon material was kinetically investigated. Decolorization process by photo-Fenton process could be divided into two established phases. At the beginning of the photo-Fenton process, the instantaneous and significant decrease in color of the solution was found. In the subsequent phase, the decolorization rate was decreased and then the decolorization was achieved. Therefore, the decolorization rate of the colored wastewater by photo-Fenton process can be expressed by two pseudo-first-order kinetics. On the other hand, the results of adsorption experiments revealed that adsorption of dyestuff in the colored wastewater onto the carbon material follows the Langmuir formula. The kinetic analysis revealed that the photo-Fenton process coupled with a carbon material had a synergistic effect. The synergistic effects could come from the reduction of ferric ions, which is the rate-limiting step in the photo-Fenton reaction, by reactions with hydroxyl groups on the carbon material and regeneration of reduction capacity of the carbon material. Our result facilitates to develop more efficient carbon material to enhance the photo-Fenton process.

Bioaerosols are floating biological particles in the air. They have gained attention as they have an environmental influence on the ecosystem because of their long-range dispersibility. Antarctica, which is almost covered by ice sheets due to low temperatures, is an isolated continent around the sea. In this study, following the 54th Japanese Antarctic Research Expedition, the author visited and conducted bioaerosol observations at the Syowa Station and Langhovde Yukidori Valley, which are designated as Antarctic Specially Protected Area and are far from residential areas; thus, people and related activities are extremely limited. Bioanalysis was conducted using next-generation sequencing. Results revealed that the bacterial compositions at the Syowa Station changed intensely; for example, Betaproteobacteria were predominant between January 12th and 15th, 2013, whereas those at the Langhovde Yukidori Valley were comparatively constant. From the results of the comparisons of the bacterial composition in the bioaerosol between the Syowa Station and Langhovde Yukidori Valley in this study, the bacterial groups thought to be of human origin were significantly different, and even the other bacterial group was significantly different. Because more bacterial groups did not show significant difference, the author revealed that there was little artificial influence at the Syowa Station.