12 results on '"Yumi Ohba"'
Search Results
2. Single-laboratory Validation Study and Surveillance Using an Improved Multiresidue Analytical Method for Veterinary Drugs in Livestock Products by LC-MS/MS
- Author
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Momoka Hayashi, Maki Kanda, Souichi Yoshikawa, Takayuki Nakajima, Hiroshi Hayashi, Yoko Matsushima, Yumi Ohba, Hiroshi Koike, Chieko Nagano, Kenji Otsuka, and Takeo Sasamoto
- Subjects
General Medicine - Published
- 2023
3. Surveillance of Acaricides in Honey
- Author
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Yumi, Ohba, Takayuki, Nakajima, Maki, Kanda, Hiroshi, Hayashi, Chieko, Nagano, Souichi, Yoshikawa, Youko, Matsushima, Hiroshi, Koike, Momoka, Hayashi, Kenji, Otsuka, and Takeo, Sasamoto
- Subjects
Japan ,Tandem Mass Spectrometry ,Honey ,General Medicine ,Acaricides ,Chromatography, Liquid - Abstract
By using the LC-MS/MS method developed by us, we determined the residual amounts of acaricides in honey samples commercially available in Tokyo from April 2015 to March 2021. The results of analyzing 127 honey samples, amitraz was detected in 85 samples at the level of 1.1-34.1 μg/kg. Propargite was detected in 3 samples at 2.4-3.8 μg/kg. None of them was beyond the Japanese MRLs or uniform limits. In these survey for 6 years, amitraz was detected in high rate throughout the year. But, the present results imply that amitraz has been used properly in actual bee-keeping because of no violation of MRL and less fluctuation in the detected levels. On the other hand, propargite was detected at the levels over LOQ in domestic honey samples for the first time in 2020, which may suggest a new trend of acaricide use in apiculture in Japan.
- Published
- 2022
4. Proteomic identification and quantification of Clostridium perfringens enterotoxin using a stable isotope-labelled peptide via liquid chromatography–tandem mass spectrometry
- Author
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Hiroshi Koike, Maki Kanda, Souichi Yoshikawa, Hiroshi Hayashi, Yoko Matsushima, Yumi Ohba, Momoka Hayashi, Chieko Nagano, Kenji Otsuka, Junichi Kamiie, and Takeo Sasamoto
- Subjects
Biochemistry (medical) ,Toxicology ,Pathology and Forensic Medicine - Published
- 2023
5. Monitoring of residual antibacterial agents in animal and fishery products in Tokyo from 2003 to 2019: application and verification of a screening strategy based on microbiological methods
- Author
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Kotaro Sekimura, Yoko Matsushima, Hiroshi Koike, Chieko Nagano, Souichi Yoshikawa, Maki Kanda, Yumi Ohba, Kenji Otsuka, Hiroshi Hayashi, Tsuneo Hashimoto, Takeo Sasamoto, Momoka Hayashi, and Takayuki Nakajima
- Subjects
medicine.drug_class ,Fisheries ,Food Contamination ,Multiple methods ,Toxicology ,Residual ,01 natural sciences ,03 medical and health sciences ,Antibiotic resistance ,Screening method ,Animals ,Medicine ,Tokyo ,Norfloxacin ,0303 health sciences ,Lincosamides ,030306 microbiology ,business.industry ,010401 analytical chemistry ,Public Health, Environmental and Occupational Health ,Food safety ,Anti-Bacterial Agents ,0104 chemical sciences ,Lincomycin ,Fishery ,Tetracyclines ,business ,Food Science ,medicine.drug - Abstract
Residual antibacterial agents in 5909 animal and fishery products in Tokyo, Japan, were investigated over 17 consecutive years (2003-2019). Monitoring of 32 antibacterial agents (lincosamides, macrolides, penicillins, quinorones and tetracyclines) per product was accomplished via two steps: screening (by microbiological methods) and confirmation (by instrumental methods). Microbiological screening methods identified presumptive groups and determined semi-quantitative values. The instrumental methods quantified 81 residues of 11 different antibacterial agents in 72 samples. The screening strategy based on microbiological methods demonstrated the following: (i) the majority of the samples (over 99%) met Japanese regulations, (ii) using multiple methods provided a reliable inspection system with accurate quantitative values and (iii) there was a constant presence of tetracyclines and unexpected residues (lincomycin and norfloxacin) in various products. Thus, this long-term monitoring and screening strategy provided evidence that the frequencies and trends of residual antibacterial agents not only enhance food safety but also help to prevent antimicrobial resistance.
- Published
- 2021
6. Determination of Antibacterial Agents for Animals in Swine Muscles by Microbiological Screening and LC-MS/MS
- Author
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Yoko Matsushima, Hiroshi Koike, Yumi Ohba, Kenji Otsuka, Hiroshi Hayashi, Maki Kanda, Chieko Nagano, Souichi Yoshikawa, Tsuneo Hashimoto, Takeo Sasamoto, Momoka Hayashi, and Kotaro Sekimura
- Subjects
Chromatography ,Swine ,Chemistry ,General Medicine ,Mass spectrometry ,Anti-Bacterial Agents ,Preparation method ,Japan ,Tandem Mass Spectrometry ,Lc ms ms ,False positive paradox ,Animals ,Geobacillus stearothermophilus ,Muscle, Skeletal ,Food Analysis ,Chromatography, Liquid - Abstract
The determination of antibacterial agents for animals in swine muscles was improved by microbiological screening and liquid chromatography-mass spectrometry (LC-MS/MS) analyses. In the first instance, the residual drugs were extracted from the samples using the Na2EDTA-McIlvaine buffer (pH 6.0). Subsequently, the agents were purified utilizing a PLS-3 cartridge and extracted with acetonitrile. Considering the microbiological methods, the sensitivities of the investigated drugs were higher and the test plate conditions were improved using a new reference organism Geobacillus stearothermophilus. As a result, a microbiological screening approach able to detect 33 drugs at MRL was developed in Japan. Remarkable, no false positives were detected. Moreover, the same preparation method enabled rapid and reliable microbiological screening, resulting in efficient screening with no undeterminable results.
- Published
- 2020
7. Quantification of staphylococcal enterotoxin type A in cow milk by using a stable isotope-labelled peptide via liquid chromatography–tandem mass spectrometry
- Author
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Hiroshi Hayashi, Junichi Kamiie, Takeo Sasamoto, Yoko Matsushima, Yukiko Nakagawa, Kotaro Sekimura, Tetsuya Shindo, Maki Kanda, Tsuneo Hashimoto, Yumi Ohba, Hiroshi Koike, Kenji Otsuka, Akihiko Hirai, and Chieko Nagano
- Subjects
Health, Toxicology and Mutagenesis ,Food Contamination ,Enterotoxin ,Toxicology ,Mass spectrometry ,Enterotoxins ,chemistry.chemical_compound ,Tandem Mass Spectrometry ,Liquid chromatography–mass spectrometry ,Animals ,Trichloroacetic acid ,Reproducibility ,Chromatography ,Chemistry ,Stable isotope ratio ,Public Health, Environmental and Occupational Health ,General Chemistry ,General Medicine ,Repeatability ,Milk ,Isotope Labeling ,Cattle ,Peptides ,Digestion ,Chromatography, Liquid ,Food Science - Abstract
In this study, the staphylococcal enterotoxin type A (SEA) contaminant was quantified in cow milk by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with the use of a stable isotope-labelled peptide of SEA as an internal standard. SEA was cleaned up in a two-step process that included pH control and trichloroacetic acid (TCA) precipitation. The pH control phase eliminated other proteins. TCA precipitation cleaned up SEA without special equipment. An appropriate enzyme-to-protein ratio maximised tryptic digestion. A desalting process guaranteed the stable retention of SEA-digested peptides. The coverage of amino-acid sequences (>10%) clearly identified the toxin's presence. SEA was accurately quantified using LC-MS/MS based on a multiple-reaction monitoring mode. The developed method was validated based on spiked recovery tests at 50 and 100 µg kg-1 conducted with two samples collected on a daily basis for five days based on Japanese validation guidelines. The new method exhibited good accuracy which ranged from 80% to 82%. The relative standard deviations of repeatability were 13-14% and the relative standard deviations of within-laboratory reproducibility were 13-18%. These standard deviations satisfied the criteria of the Japanese validation guidelines. The quantification limit was estimated to be 10 µg kg-1.
- Published
- 2019
8. Simultaneous determination of nine acaricides and two metabolites in comb honey by LC/MS/MS
- Author
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Kotaro Sekimura, Tsuneo Hashimoto, Chieko Nagano, Maki Kanda, Takeo Sasamoto, Hiroshi Hayashi, Yumi Ohba, Kenji Otsuka, Yukiko Nakagawa, Takayuki Nakajima, Hiroshi Koike, and Youko Matsushima
- Subjects
Chromatography ,Chemistry ,Acaricide ,Health, Toxicology and Mutagenesis ,010401 analytical chemistry ,Public Health, Environmental and Occupational Health ,Honey ,General Chemistry ,General Medicine ,010501 environmental sciences ,Toxicology ,01 natural sciences ,Comb honey ,0104 chemical sciences ,Tandem Mass Spectrometry ,Lc ms ms ,Acaricides ,Chromatography, Liquid ,0105 earth and related environmental sciences ,Food Science - Abstract
We developed a method for the simultaneous determination of acaricides in comb honey using LC/MS/MS. Because methods for honey analysis had not previously been applied to comb honey, we modified three techniques for sample preparation and LC/MS/MS conditions. First, we used a modified QuEChERS method that changed the extraction solution from ethyl acetate to acetonitrile. Second, we replaced the InertSep® MA-1 (30 mg, 1 ml) clean-up cartridge with an Oasis® HLB (60 mg, 3 ml). Third, we changed the ionisation mode from ESI to atmospheric pressure chemical ionisation (APCI). With these modifications, sample matrices had no effect on the identification and quantification of analytes, using an external solvent calibration curve. We verified this new method with nine acaricides and two metabolites on comb honey and honey samples from three different honey origins. The trueness ranged from 74.0 to 99.4%. The relative standard deviation of repeatability (RSD
- Published
- 2018
9. Development of an alternative approach for detecting botulinum neurotoxin type A in honey: Analysis of non-toxic peptides with a reference labelled protein via liquid chromatography-tandem mass spectrometry
- Author
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Kotaro Sekimura, Yumi Ohba, Kenji Otsuka, Hiroshi Koike, Takeo Sasamoto, Junichi Kamiie, Momoka Hayashi, Yoko Matsushima, Hairoshi Hayashi, Tsuneo Hashimoto, Chieko Nagano, Souichi Yoshikawa, and Maki Kanda
- Subjects
0303 health sciences ,Chromatography ,Botulinum Neurotoxin Type A ,Chemistry ,Health, Toxicology and Mutagenesis ,010401 analytical chemistry ,Public Health, Environmental and Occupational Health ,Food Contamination ,General Chemistry ,General Medicine ,Honey ,Toxicology ,01 natural sciences ,0104 chemical sciences ,03 medical and health sciences ,Liquid chromatography–mass spectrometry ,Tandem Mass Spectrometry ,Botulinum Toxins, Type A ,Peptides ,Peptide sequence ,Food Analysis ,030304 developmental biology ,Food Science ,Chromatography, Liquid ,Plant Proteins - Abstract
In this study, we developed a reference labelled protein containing the partial amino acid sequence of botulinum neurotoxin type A (BoNTA). We also applied it as an internal standard to detect specific and non-toxic peptides originated from BoNTA in honey with the use of liquid chromatography-tandem mass spectrometry (LC-MS/MS). Original proteins in the honey sample were collected through a two-step process that included solubilisation and trichloroacetic acid (TCA) precipitation. Solubilisation by adding water enabled processing of proteins in honey. TCA precipitation collected proteins without specific binding. The combination of protein alkylation and an appropriate enzyme-to-protein ratio ensured feasibility of tryptic digestion. A desalting process eliminated a large amount of salts and other tryptic peptides in the honey sample. The use of the reference labelled protein enabled compensation for tryptic digestion efficiency and electrospray ionisation efficiency based on LC-MS/MS measurement. After the peptide selection and protein BlastP analysis, five unique peptides were chosen. The non-toxic peptides originating from BoNTA were reliably detected using LC-MS/MS based on a multiple-reaction monitoring mode. Detection of several peptides ensured screening of BoNTA in honey samples. Based on the responses, the proteotypic peptide LYGIAINPNR was selected as the quantitative peptide. Due to maintaining the relative ion ratios, the selective transition completely identified the non-toxic peptides. The intensity of the transitions established a detection limit of BoNTA estimated to be 9.4 ng mL
- Published
- 2020
10. [Determination of Antifungal Drugs in Fish and Livestock Products Using LC-MS/MS]
- Author
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Yoko Matsushima, Tsuneo Hashimoto, Kotaro Sekimura, Yumi Ohba, Chieko Nagano, Kenji Otsuka, Yukiko Nakagawa, Maki Kanda, Hiroshi Hayashi, Hiroshi Koike, and Takeo Sasamoto
- Subjects
Drug ,Reproducibility ,Chromatography ,Veterinary Drugs ,Antifungal Agents ,Meat ,business.industry ,Chemistry ,Antifungal drugs ,media_common.quotation_subject ,Reproducibility of Results ,Food Contamination ,General Medicine ,Repeatability ,Matrix (chemical analysis) ,Cartridge ,Seafood ,Tandem Mass Spectrometry ,Animals ,Livestock ,business ,media_common ,Chromatography, Liquid - Abstract
We developed an analytical method for determining 15 antifungal drugs, 2 antiparasitic drugs, and 3 veterinary drugs in fish and livestock products using LC-MS/MS. First, 50% ethanol was added to their products, and the mixture was homogenized to reduce drug degradation. Thereafter, 20 drugs were extracted from the pretreated sample mixture using acetonitrile. Cleanup was performed using an alumina-N SPE cartridge. Finally, chromatographic separation was performed using a fully porous octadecyl silanized silica column. The new method is applicable to fish in which the matrix hampers accurate analysis. It was validated on 8 fish and livestock products. Drug recovery rates ranged from 70.2 to 109.3%, RSDs of repeatability were
- Published
- 2019
11. Identification and quantification of cereulide in cow's milk using liquid chromatography-tandem mass spectrometry
- Author
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Akihiko Hirai, Yoko Matsushima, Hiroshi Koike, Kotaro Sekimura, Chieko Nagano, Tetsuya Shindo, Maki Kanda, Hiroshi Hayashi, Yukiko Nakagawa, Takeo Sasamoto, Tsuneo Hashimoto, Yumi Ohba, and Junichi Kamiie
- Subjects
0301 basic medicine ,Health, Toxicology and Mutagenesis ,030106 microbiology ,Food Contamination ,Toxicology ,Mass spectrometry ,03 medical and health sciences ,chemistry.chemical_compound ,Milk products ,Liquid chromatography–mass spectrometry ,Tandem Mass Spectrometry ,Depsipeptides ,Animals ,Chromatography, High Pressure Liquid ,Chromatography ,Public Health, Environmental and Occupational Health ,food and beverages ,General Chemistry ,General Medicine ,Repeatability ,Cereulide ,Raw milk ,Milk ,chemistry ,Calibration ,Cattle ,Food Science - Abstract
In this study, the presence of cereulide in cow's milk was identified and quantified using our validated method with liquid chromatography-tandem mass spectrometry. Cereulide was concentrated using protein acid-precipitation and extracted from the precipitate by using acetonitrile twice. The combination of protein acid-precipitation and extraction sufficiently eliminated the matrix compounds from the milk and a further clean-up step utilising solid-phase extraction could be omitted. For robustly measuring the samples and keeping the MS devices clean, the extraction solution was diluted 10-fold using methanol. Owing to the minimisation of the interferences caused by fragmentation patterns, multiple reaction monitoring information-dependent acquisition-enhanced product ion spectra enabled the characterisation and identification of cereulide. Besides the matrix effect (-4%), an external solvent calibration curve was adapted for accurate quantification. The method was validated using fortified recovery tests, at two concentrations (10 and 50 µg kg
- Published
- 2018
12. [Determination of Cyromazine in Livestock Products by LC-MS/MS on an Anion-Cation Exchange Mode ODS Column]
- Author
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Yumi Ohba, Chieko Nagano, Hiroshi Hayashi, Maki Kanda, Hiroshi Koike, Yoko Matsushima, Kotaro Sekimura, Yukiko Nakagawa, Yuki Okutomi, and Tsuneo Hashimoto
- Subjects
Anions ,Chromatography ,Chemistry ,Calibration curve ,Triazines ,Eggs ,Extraction (chemistry) ,General Medicine ,Repeatability ,Cyromazine ,Ion ,chemistry.chemical_compound ,Cartridge ,Milk ,Tandem Mass Spectrometry ,Cations ,Animals ,Ammonium ,Methanol ,Food Analysis ,Chromatography, Liquid - Abstract
Cyromazine in livestock products was determined using a validated LC-MS/MS method. There are three key points in our methods. First, the extraction was performed with two solutions, methanol and pH 3.0 McIlvaine buffer. The process was optimized for each type of sample. Secondly, cleanup was performed using a reversed-phase and strong cation exchange mixed-mode cartridge. The cartridge was washed with 0.14% ammonium solution. Thirdly, the chromatographic separation was performed on an anion-cation exchange mode ODS column. There was no matrix effect on the extraction and determination for five livestock products. The quantification was carried out using an external standard calibration curve. This new method satisfies the Japanese guideline criteria. Recovery ranged from 77.2 to 92.1%, the relative standard deviation of repeatability (RSDr) was under 2.2%, and RSDwr was under 6.1%. Residual cyromazine was detected in raw milks and eggs.
- Published
- 2018
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