Nishikawa Keisoku Co.

Yokohama-shi, Japan

Nishikawa Keisoku Co.

Yokohama-shi, Japan
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Miyazaki T.,Nippon Steel Kankyou Engineering Co. | Miyazaki T.,Kyushu Institute of Technology | Kadokami K.,University of Kitakyushu | Sonoda Y.,Nippon Steel Kankyou Engineering Co. | And 4 more authors.
Bunseki Kagaku | Year: 2011

The reproducibility of measurement results by automated identification and quantification system with a database (AIQS-DB) for GC-MS, which can determine a large number of chemical substances without using their standard substances, has been studied to evaluate the dispersion and to identify the causes of an increase of the dispersion. The reproducibility was examined with 4 GC-MS in 4 laboratories using 114 substances comprising a wide range of physicochemical properties that are difficult to be measured with a GC. As a result, when the performance of a GC-MS passed the designated criteria, the reproducibility of quantification results of 47 substances was almost the same as that obtained by the conventional method that prepares calibration curves before sample analysis. Although the reproducibility of 42 substances was slightly lower than that by the conventional method, the reproducibility is sufficiently reliable, except for in cases that require a high reliability. However, the dispersion of the results of 25 substances was large under the GC conditions used in this study, which indicates that AIQS-DB can only be used as screening for these substances. The causes that affect the dispersion of quantification results are functional groups and the structures of the molecules. The effects of the functional groups are hydroxyl >= amino>nitro group. The effects of the number of them is multiple> single. The position of them can also have different effects: farther>nearer. In the case of the structure of molecules, the effects are as follows: side chain> straight chain> single benzene>multiple benzenes. © 2011 The Japan Society for Analytical Chemistry.

Sugitate K.,Agilent Technologies | Sugitate K.,Kanazawa University | Yamagami T.,Nishikawa Keisoku Co | Yamagami T.,University of Kitakyushu | And 3 more authors.
Analytical Sciences | Year: 2012

Fenthion, fenthion sulfoxide, fenthion oxon sulfoxide and fensulfothion showed two different mass spectra in GC/MS, depending on their concentrations. The base peaks shifted to lower levels by 1 m/z at lower concentration, and no retention time shifts were observed. The "shifted base peaks" were not obtained by a general EI fragmentation. The product ion scan spectra of the "shifted base peaks" were coincident with those of molecular ions of their corresponding sulfides. These phenomena can be ascribed to the conversion of sulfoxide into sulfide by the dominant deoxidation reaction than EI fragmentation in an ion source. Adding polyethylene glycol 300 (PEG300) into a test solution prevented sulfoxide deoxidation. © The Japan Society for Analytical Chemistry.

Nakamura S.,Agilent Technologies | Yamagami T.,Nishikawa Keisoku Co. | Ono Y.,Nishikawa Keisoku Co. | Toubou K.,Shinkawa Electrical Co. | Daishima S.,Agilent Technologies
Bunseki Kagaku | Year: 2013

A method for determining 305 pesticides by GC/MS using synchronous SIM/Scan acquisition is described; 111 pesticides that could not be detected adequately in the scan mode among the 305 pesticides were selected for SIM acquisition. The other 194 pesticides were acquired in the scan mode. The SIM/Scan method allowed us to detect 301 pesticides at 0.02 ppm (test solution) in a single run. The method dramatically increases the number of compounds in a single run with high sensitivity. The recovery of the method was tested by a replicate analysis (n = 3) of seven agricultural products spiked with standards at 0.05 ppm using sample preparation based on the Ministry of Health, Labour and Welfare. Good recoveries were obtained for about 80 % of pesticides with values of between 70 and 120 %. Furthermore, screening software with deconvolution (NIST AMDIS) using the database of the mass spectra and retention times of 429 pesticides is also described. Scan data in SIM/Scan acquisition was used for screening. The software was useful for screening 429 pesticides in non-spiked agricultural products by optimizing the AMDIS settings. © 2013 The Japan Society for Analytical Chemistry.

Taira J.,Okinawa National College of Technology | Tsuchiya A.,Nishikawa Keisoku Co. | Furudate H.,Nishikawa Keisoku Co.
Food Science and Technology Research | Year: 2012

The natural vaporized aroma compounds present in awamori shochu were determined by a threestage volatile organic compound (VOC) concentration technique consisting of on-line GC combined with MSD and PFPD. Several short-chain esters appear to predominantly contribute to the fruity aroma, including ethyl formate, methyl formate, ethyl propionate, and ethyl butyrate, which are typically contained in the natural vaporized aroma of awamori. Compounds that act as stimulant flavor compounds, including 2-methyl propanal, 3-methyl butanal, pentanal, hexanal, octanal, nonanal, and the ketones 2-butanone, 4-methyl-2-pentanone, 2-heptanone, and 3-octanone, were also detected as minor components. Sulfur compounds that impart strong odor/flavor, such as dimethyl trisulfide, benzothiazole, dimethyl trisulfide, and benzothiazole, were detected initially, but their levels tended to decrease with aging. We also found that ethers, including tetrahydrofuran and 1,1-diethoxyethane, increased in aged awamori. Thus the profiles of these compounds changed during aging, resulting in a milder and sweeter flavor. These results suggest that the natural vaporized aroma would contribute to the initial characteristics of the unique awamori aroma.

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