Mikiya Kitagawa - Academia.edu (original) (raw)

Papers by Mikiya Kitagawa

Journal of Environmental Chemistry, 2011

Summar y Perchlorate concentrations in raw and tap water in Osaka, Japan, were determined by IC-M... more Summar y Perchlorate concentrations in raw and tap water in Osaka, Japan, were determined by IC-MS/MS. The concentrations of perchlorate in raw water and tap water were in the ranges from ＜0． 015 to 0． 48 µg/L and from ＜0． 015 to 0． 82 µg/L, respectively. Except for only a few cases, the perchlorate concentration in each tap water sample was at nearly equivalent level to that in the corresponding raw water. The results indicate that perchlorate in raw water was not removed effectively by the ordinary water treatment methods such as ozonation, granular activated carbon adsorption, rapid and slow sand filtrations. On the other hand, perchlorate was found to be contained in sodium hypochlorite solutions, used in the chlorination process, at wide concentration range between 4． 9 and 5900 µg/L. In the case using disinfectant with the highest perchlorate content, the significant increase in perchlorate concentration in tap water was observed, compared to that in raw water. However, when 2 L of tap water was ingested every day, the corresponding perchlorate intake was estimated to be at most 1． 8 µg/day from the observed perchlorate concentrations in tap water samples. This value was sufficiently lower than the calculated daily intake for a person weighing 50 kg from reference dose value of perchlorate. Therefore, the health risk to humans from perchlorate in tap water in Osaka, Japan, is very low.

Food Hygiene and Safety Science (Shokuhin Eiseigaku Zasshi), 1998

YAKUGAKU ZASSHI, 2006

Many methods for the determination of pesticides residues in food have been reported. Although na... more Many methods for the determination of pesticides residues in food have been reported. Although natural medicines should be conˆrmed as safe as food, only a few methods for the determination of pesticide residues in natural medicines have been reported. In this study, 10 pyrethroid pesticides were detected in natural medicines by GC/MS with negative chemical ionization (NCI). GC/MS with NCI can detect halogenated pesticides selectively, and thus is suitable for the detection of pyrethroid pesticides. This study indicates that GC/MS with NCI is useful for analyzing pyrethroid pesticides in natural medicines.

YAKUGAKU ZASSHI, 2007

Many methods for the determination of pesticide residues in food have been reported. Although nat... more Many methods for the determination of pesticide residues in food have been reported. Although natural medicines should be conˆrmed to be as safe as food, few methods for the determination of pesticide residues in natural medicines have been reported. In this study, 17 organochlorine pesticides were detected in natural medicines using GC/MS with negative chemical ionization (NCI). GC/MS with NCI can detect halogenated pesticides selectively and thus is suitable for the detection of organochlorine pesticides. This study indicates that GC/MS with NCI is useful for analyzing organochlorine pesticides in natural medicines.

Journal of Medical Virology, 2006

Human cytomegalovirus (CMV) is a leading congenital infectious agent in developed countries. In t... more Human cytomegalovirus (CMV) is a leading congenital infectious agent in developed countries. In the past, the incidence of congenital infection has been rather low in Japan because a high seroprevalence of CMV present in young women. However, this seroprevalence has been decreasing in recent years, so that the incidence of congenital CMV infection in Japanese neonates may increase and approach the level seen in other developed countries. The method was used for detecting CMV DNA reported by Barbi et al. [Barbi et al. (1996): Clin Diagn Virol 6:27-32] using a dried blood spot on filter paper, to diagnose congenital CMV infection in Japanese neonates. This method is effective and less laborious than virus isolation both for epidemiological studies and for identifying asymptomatic infected babies. Japanese neonates (1,176) were examined; two of who were asymptomatic were found to be infected.

JOURNAL OF HEALTH SCIENCE, 2000

Journal of Health Science, 2000

Journal of Chromatography B, 2004

Concentrations of mono(2-ethylhexyl)phthalate (MEHP), and di(2-ethylhexyl)phthalate (DEHP), in se... more Concentrations of mono(2-ethylhexyl)phthalate (MEHP), and di(2-ethylhexyl)phthalate (DEHP), in serum of healthy volunteers were determined by high performance liquid chromatography (HPLC) with tandem mass spectrometry (LC/MS/MS). The serum was extracted with acetone, followed by hexane extraction under acidic conditions, and then applied to the LC/MS/MS. Recoveries of 20 ng/ml of MEHP and DEHP were 101 ± 5.7 (n = 6) and 102 ± 6.5% (n = 6), respectively. The limits of quantification (LOQ) of MEHP and DEHP in the method were 5.0 and 14.0 ng/ml, respectively. The concentration of MEHP in the serum was at or less than the LOQ. The concentration of DEHP in the serum was less than the LOQ. Contaminations of MEHP and DEHP from experimental reagents, apparatus and air during the procedure were less than the LOQ and were estimated to be <1.0 and 2.2 ± 0.6 ng/ml, respectively. After subtraction of the contamination, the net concentrations of MEHP and DEHP in the serum were estimated at or <5 and <2 ng/ml, respectively. To decrease contamination by DEHP, the cleanup steps and the apparatus and solvent usage were minimized in the sample preparation procedures. The high selectivity of LC/MS/MS is the key for obtaining reliable experimental data from in the matrix-rich analytical samples and for maintaining a low level contamination of MEHP and DEHP in this experimental system. This method would be a useful tool for the detection of MEHP and DEHP in serum.

Food Microbiology, 2013

The Bacillus cereus emetic toxin cereulide causes foodborne intoxication, which may occasionally ... more The Bacillus cereus emetic toxin cereulide causes foodborne intoxication, which may occasionally result in severe disease, and even death. To differentially diagnose the emetic-type of foodborne disease caused by B. cereus and assess the safety of commercial food, we developed a rapid method to quantitate cereulide. This method was combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis for the extraction of cereulide from food using a normal-phase silica gel cartridge. The limits of detection and quantification were 0.1 and 0.5 ng of cereulide ml(-1), respectively. Spiked cereulide was reproducibly recovered with over 67% efficiency from nine diverse foods implicated in cereulide food poisoning. The recovery rate, reproducibility, and intermediate precision for this single laboratory validation using boiled rice were 87.1%, 4.4%, and 7.0%, respectively. Further, we detected a wide range of cereulide concentrations in leftover food and vomitus samples from two emetic foodborne outbreaks. LC-MS/MS analysis correlated closely with those acquired using the HEp-2 cell assay, and quantitated cereulide from 10 food samples at least five times faster than the bioassay. This new method will provide clinicians with an improved tool for more rapidly and quantitatively determining the presence of cereulide in food and diagnosing food poisoning caused by cereulide.

Chemosphere, 2001

Development of an analytical method for polybrominated diphenyl ethers (PBDEs) in ®sh and their c... more Development of an analytical method for polybrominated diphenyl ethers (PBDEs) in ®sh and their concentration in Japanese marine ®sh were investigated. Fish homogenate was extracted with diethyl ether/hexane 1 3. The extract was cleaned up by automated gel permeation chromatography (GPC) and then by mini-column chromatography, which consisted of three layers of silica gel and sulfuric acid-impregnated silica gel. The PBDE fraction was concentrated and injected into a GC/MS with negative chemical ionization (NCI).

Chemosphere, 2003

The time-trend and recent concentrations of polybrominated diphenyl ethers (PBDEs) in Japanese mo... more The time-trend and recent concentrations of polybrominated diphenyl ethers (PBDEs) in Japanese mother's milk were investigated. The time-trend of 16

Bulletin of Environmental Contamination and Toxicology, 2001

Analytical Sciences, 2009

A highly sensitive and simple method for the analysis of chlorothalonil was presented using a liq... more A highly sensitive and simple method for the analysis of chlorothalonil was presented using a liquid chromatograph/mass spectrometer equipped with an atmospheric pressure photoionization (APPI) source. Chlorothalonil is one of the most extensively used fungicides. The major degraded product of chlorothalonil, 4-hydroxy-2,5,6-trichloroisonaphthonitrile (4OH-TPN), was also quantified with sensitivity similar to that of chlorothalonil. The method was applied to the determination of chlorothalonil in aqueous environment and food samples. The method detection limits (MDLs) of chlorothalonil for aqueous samples and cucumber were determined to be 0.18 and 3.2 ng g-1 , respectively. At several estuarial locations, chlorothalonil was detected with a maximum of 1.1 ng L-1. On the other hand, 4OH-TPN was detected not from estuaries but from rivers with a maximum of 14 ng L-1 .

Journal of the Food Hygienic Society of Japan (Shokuhin Eiseigaku Zasshi), 2007

A simple and rapid method using refractive index high-performance liquid chromatography (RI-HPLC)... more A simple and rapid method using refractive index high-performance liquid chromatography (RI-HPLC) was developed for the determination of polysorbates (PS) in processed foods. PS were extracted with ethyl acetate containing 5 methanol. The extract was cleaned up on a multimode cartridge (300 mg) and an Alumina-N cartridge (500 mg) to remove fats and food color. HPLC separation was performed on a C18 column (4.6 i.d.150 mm) with methanol as the mobile phase. The recoveries of PS80 from nine kinds of foods fortified at the levels 1ῌ5 g/kg were 80ῌ99. The limit of quantitation for PS80 in foods was 0.10 g/kg. The proposed method was applied to Worcestershire sauce that was PS-positive by TLC, and PS was confirmed to be present as PS80 at the concentration of 0.13 g/kg.

Environmental Health and Preventive Medicine, 2006

Objective: Because the analysis of polychlorinated biphenyls (PCBs) in 1970's was performed using... more Objective: Because the analysis of polychlorinated biphenyls (PCBs) in 1970's was performed using a packed column gas chromatograph with an electron capture detector to determine total-PCB concentration, analytical data obtained by this analysis do not meet the requirement for the risk assessment of PCB congeners. In this context, the present study was carried out to reevaluate the congeneric analysis data by analyzing breast milk fat specimens that have been kept frozen. Methods: PCB congeners in human breast milk were analyzed by high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS) using a capillary column for the selected ion monitoring (SIM) of PCBs. Results: Twelve major PCB congeners were detected in breast milk. The concentrations of all congeners of PCBs in breast milk were found to decrease annually, and their changes over time differed greatly for each congener. Between 1973 and 2000, almost no changes in the proportions of the 12 congeners of heptachlorinated biphenyls (HpCBs) and hexachlorinated biphenyls (HxCBs) were found whereas a marked and a slight decrease in the proportion of pentachlorinated biphenyls (PeCBs) and tetrachlorinated biphenyls (TeCBs), respectively, were observed. Conclusions: The PCB contamination of the Japanese population is estimated to be largely caused by seafood intake, but the proportions of PCB congeners in fish commodities were different from those in breast milk. The absorption, metabolism and therefore the accumulation of PCBs in the human body differ greatly depending on the congener.