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Volume 44 (2003)
- Issue 6 Pages 269-
- Issue 5 Pages 213-
- Issue 4 Pages 181-
- Issue 3 Pages 145-
- Issue 2 Pages 77-
- Issue 1 Pages 1-
Volume 44, Issue 2
Displaying 1-10 of 10 articles from this issue
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Originals
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Haruyo OKUNUKI, Hiroshi AKIYAMA, Reiko TESHIMA, Akihiro HINO, Yukihiro ...2003 Volume 44 Issue 2 Pages 77-82
Published: April 25, 2003
Released on J-STAGE: January 21, 2009
JOURNAL FREE ACCESSA liquid chromatography-mass spectrometry (LC/MS) method for determining the enzymatic activity of 5-enolpyruvylshikimate-3-phosphate synthase (EPSP synthase), an enzyme of the shikimate pathway, was developed. EPSP synthase catalyzes the formation of 5-enolpyruvyl-shikimate-3-phosphate (EPSP) from shikimate-3-phosphate (S-3-P) and phosphoenolpyruvate (PEP) in microorganisms and plants. The enzymatic activity of EPSP synthase was assessed by the determination of EPSP after a 30-min incubation with S-3-P and PEP using the LC/MS system. EPSP synthase activity is given in terms of the produced EPSP (pmol/min/mg protein). Glyphosate (N-phosphonomethyl glycine)-tolerant EPSP synthase from the Agrobacterium sp. strain CP4 (CP4-EPSP synthase) in genetically modified soybeans (GM-soybeans) was found to have an enzymatic activity of 736 EPSP pmol/min/mg protein in the presence of 3 nmol of S-3-P. In contrast, the enzyme activity of non-GM-soybeans was 21 EPSP pmol/min/mg protein. The EPSP synthase activity was markedly decreased in the non-GM-soybeans by the addition of glyphosate, but the enzyme activity of the GM-soybeans was only slightly decreased with this treatment. This LC/MS system could also be applicable to the measurement of EPSP synthase activity in different plant species and the detection of herbicide-tolerant EPSP synthase in GM foods.View full abstractDownload PDF (277K) -
Hiroshi FUJIKAWA, Satoshi MOROZUMI2003 Volume 44 Issue 2 Pages 83-88
Published: April 25, 2003
Released on J-STAGE: January 21, 2009
JOURNAL FREE ACCESSRecently we have developed new kinetic methods of bacterial cell estimation in food products by measurement of the increase in bacterial adenosine-triphosphate (ATP) content during incubation using a conventional firefly luminometer [Fujikawa and Morozumi: Jpn. J. Food Hyg. (2002)]. The methods were the end point method and the delay method. We, in this study, evaluated these methods for bacterial concentration estimation in commercial foods. The methods were successfully applied to food products inoculated with Escherichia coli or Staphylococcus aureus. The methods were then used to estimate bacterial concentrations in commercial foods. For estimation, the kinetic parameter values were determined first from the data of bacterial strains studied previously. The bacterial concentrations estimated with these parameter values were slightly smaller than the measured concentrations for most of the food samples. The parameter values obtained with the least-squares method gave better estimations in both methods. The delay method predicted the bacterial concentrations in food products better than the end point method. This study showed that with appropriate parameter values, these methods could be useful tools for bacterial concentration estimation of commercial foods.View full abstractDownload PDF (226K) -
Satoshi TAKATSUKI, Satoru NEMOTO, Kumiko SASAKI, Tamio MAITANI2003 Volume 44 Issue 2 Pages 89-95
Published: April 25, 2003
Released on J-STAGE: January 21, 2009
JOURNAL FREE ACCESSAn LC/MS method was developed for the determination of acrylamide (AA) in processed or cooked foods. AA was extracted with a mixture of water and acetone from homogenized food samples after the addition of 13C-labeled acrylamide (AA-1-13C) as an internal standard. The extract was concentrated, washed with dichloromethane for defatting, and cleaned up on Bond Elut C18, PSA and ACCUCAT cartridge-columns, and then AA was determined by LC/MS in the selected ion recording (SIR) mode. For the LC/MS analysis, four LC columns were connected in-line and the flow of the mobile phase was switched according to a time-program. Monitoring ions for AA were m/z 72 and 55, and those for AA-1-13C were m/z 73 and 56. AA and AA-1-13C were determined without interference from the matrices in all samples. The recoveries of AA from potato chips, corn snack, pretzel and roasted tea spiked at the level of 500 ng/g of AA were 99.5-101.0% with standard deviations (SD) in the range from 0.3 to 1.6%. The limits of detection and quantification of the developed method were 9 and 30 ng/g for AA in samples, respectively.
The method was applied to the analysis of AA in various processed or cooked food samples purchased from retail markets. High levels of AA were found in potato chips and French-fried potato (467-3,544 ng/g). Fried and sugar-coated dough cakes (karinto) contained 374 and 1,895 ng/g. Corn snacks contained 117-535 ng/g of AA. Roasted foods (such as roasted sesame seed, roasted barley (mugi-cha), roasted tea (hoji-cha), coffee beans and curry powder) contained 116-567 ng/g of AA. Foods made from fish, egg and meat contained lower levels of AA than the plant-based foods. Foods containing much water showed a tendency to have low levels of AA compared with dry foods.
The proposed method was applicable to the analysis of AA in variety of processed foods.View full abstractDownload PDF (246K) -
Takiko SUGITA, Yoko KAWAMURA, Masako TANIMURA, Rieko MATSUDA, Tatsuhir ...2003 Volume 44 Issue 2 Pages 96-102
Published: April 25, 2003
Released on J-STAGE: January 21, 2009
JOURNAL FREE ACCESSDaily oral exposure of babies to phthalate was estimated on the basis of the mouthing time of infants and the oral concentration of diisononyl phthalate (DINP) released from polyvinyl chloride (PVC) toy specimens.
Total mouthing time, including the use of pacifiers, ranged widely from 11.4 min to 351.8 min with the mean of 105.3±72.1 min. The mean of the total mouthing time without pacifiers was 73.9±32.9 min.
The average amount of DINP in saliva was 92.4±56.8 μg/10 cm2/hr, ranging from 13.2 μg/10 cm2/hr to 240.4 μg/10 cm2/hr.
The exposure of phthalate in two different trials was estimated by the method of Monte Carlo simulation, one with the total mouthing time with pacifiers and the other with the total mouthing time without pacifiers. The average exposure in the former trial was 21.4 μg/kg/day and the 95th percentile was 65.8 μg/kg/day, while in the latter it was 14.8 μg/kg/day and the 95th percentile was 35.7 μg/kg/day.View full abstractDownload PDF (746K) -
Motoh MUTSUGA, Yoko KAWAMURA, Chiseko WAKUI, Tamio MAITANI2003 Volume 44 Issue 2 Pages 103-109
Published: April 25, 2003
Released on J-STAGE: January 21, 2009
JOURNAL FREE ACCESSPolyvinyl chloride gloves containing di(2-ethylhexyl) phthalate are restricted for food contact use. In their place, disposable gloves made from nitrile-butadiene rubber (NBR) are used in contact with foodstuffs. Some unknown substances were found to migrate into n-heptane from NBR gloves. By GC/MS, HR-MS and NMR, their chemical structures were confirmed to be 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (used as a plasticizer), 4,4'-butylidenedi(6-tert-butyl-m-cresol), a mixture of styrenated phenols consisting of 2-(α-methylbenzyl)phenol, 4-(α-methyl-benzyl)phenol, 2,6-di(α-methylbenzyl)phenol, 2,4-di(α-methylbenzyl)phenol and 2,4,6-tri(α-methyl-benzyl)phenol (used as antioxidants), and 2,4-di-tert-butylphenol, which seems to a degradation product of antioxidant. Migration levels of these compounds were 1.68 μg/cm2 of 2,4-di-tert-butylphenol, 2.80 μg/cm2 of 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, 46.08 μg/cm2 of styrenated phenols and 4.22 μg/cm2 of 4,4'-butylidenedi(6-tert-butyl-m-cresol) into n-heptane, respectively. The content of total styrenated phenols was 6,900 μg/g in NBR gloves.View full abstractDownload PDF (646K)
Notes
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Maki KANDA, Keiko USHIYAMA, Kyoko IGUSA, Mitsunori MURAYAMA, Masakazu ...2003 Volume 44 Issue 2 Pages 110-113
Published: April 25, 2003
Released on J-STAGE: January 21, 2009
JOURNAL FREE ACCESSA simple and rapid determination of anticoccidial drug residues, diclazuril (DCZ) and nicarbazin (NCZ), in chicken tissues has been developed. DCZ and NCZ were extracted with acetonitrile from chicken liver, muscle, and fat. The extract was rinsed with n-hexane saturated with acetonitrile and then evaporated. The residue was dissolved in 1.4 mL of acetonitrile-methanol (1 : 1), then 1.0 mL of n-hexane saturated with acetonitrile-methanol (1 : 1) was added, and the mixture was partitioned by the addition of 0.6 mL of water. DCZ and NCZ in the aqueous layers were determined by HPLC on an Xterra RP-18 column with acetonitrile-0.5% ammonium acetate containing 0.01 mol/L tetra-n-butylammonium hydrogen sulfate (43 : 57) as the mobile phase. The mean recoveries (n=5) of DCZ and NCZ spiked in chicken tissues at the maximum residue levels were 92.0∼95.6% (CV 2.4∼3.0%) and 87.3∼89.4% (CV 1.7∼2.8%), respectively. The detection limits of DCZ and NCZ were 0.01 and 0.004 μg/g, respectively.View full abstractDownload PDF (418K) -
Kouko HAMAMOTO, Yasuharu MIZUNO, Ryoji KOIKE, Ryozo YAMAOKA, Toshio TA ...2003 Volume 44 Issue 2 Pages 114-118
Published: April 25, 2003
Released on J-STAGE: January 21, 2009
JOURNAL FREE ACCESSA reversed-phase HPLC method with ultraviolet detection using p-nitrophenyl hydrazine as a pre-column derivatizing reagent was investigated for the determination of the antibiotic spectinomycin (SPCM) in muscle, liver, kidney and fat of chicken and swine. SPCM was extracted from samples with 10% trichloroacetic acid saturated with EDTA-2Na, and then cleaned up with coupled Sep-Pak Plus PS-2 cartridges. The detection limit of SPCM was 0.02 μg (potency)/g. Recoveries of SPCM ranged from 77.4 to 97.4% for chicken tissues and from 74.5 to 91.8% for swine tissues. The present method was used for the analysis of chicken tissues after the 11th day of withdrawal (SPCM-medicated drinking water : 500 mg (potency)/L, for 7 days), and swine tissues after the 14th day of withdrawal (SPCM-medicated feed: 100 mg (potency)/kg, for 7 days). Results showed that SPCM concentrations were lower than the MRLs in all tissues.View full abstractDownload PDF (491K) -
Yoshiaki AMAKURA, Tomoaki TSUTSUMI, Kumiko SASAKI, Masatake TOYODA, Ta ...2003 Volume 44 Issue 2 Pages 119-125
Published: April 25, 2003
Released on J-STAGE: January 21, 2009
JOURNAL FREE ACCESSThe cleanup procedure for the determination of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (PCBs) in food samples using a disposable pre-packed multi-layer silica gel column (multi-layer dioxin tube; D-tube) was evaluated. The blank test showed the need for conditioning of the column with n-hexane. To compare the method with the D-tube and the conventional method for the analyses of actual food samples, seven food samples (spinach, komatsuna, rice, salmon, beef, egg and butter) were extracted by shaking with acetone-n-hexane or n-hexane after alkaline treatment, and then the extracts were cleaned up by use of the D-tube or the prepared conventional column, followed by several column chromatographic steps. Both cleanup procedures gave similar values at each isomeric concentration level and showed similar efficiency with favorable recoveries. The results suggest that the D-tube is applicable to cleanup for the analysis of PCDD/Fs and dioxin-like PCBs in foods.View full abstractDownload PDF (354K) -
Toshihiro NAGAYAMA, Ichiro TAKANO, Maki KOBAYASHI, Yasuhiro TAMURA, Sa ...2003 Volume 44 Issue 2 Pages 126-131
Published: April 25, 2003
Released on J-STAGE: January 21, 2009
JOURNAL FREE ACCESSA simple and rapid method is described for the determination of the non-registered pesticides, captafol, quintozene (PCNB), cyhexatin and 1-naphthylacetic acid (NAA), in fruits. These pesticides were extracted with acidified acetone, then captafol and PCNB were purified with a Florisil mini column and analyzed by GC-ECD. Cyhexatin was ethylated with ethylmagnesium bromide, and the ethyl derivative was analyzed by GC-FPD (Sn filter). NAA was purified with liquid-liquid extraction and determined by HPLC equipped with a fluorescence detector. These analytes were identified with GC/MS or LC/MS. The minimum identified concentration of the pesticides was below 0.2 ng per injection, which corresponds to a detection limit of below 0.02 μg/g in the original samples. Recoveries of the pesticides spiked at 0.1 μg/g into apple, Japanese pear and melon were greater than 61%.View full abstractDownload PDF (690K)
Report
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Hajimu ISHIWATA, Motohiro NISHIJIMA, Yoshinobu FUKASAWA2003 Volume 44 Issue 2 Pages 132-143
Published: April 25, 2003
Released on J-STAGE: January 21, 2009
JOURNAL FREE ACCESSThe mean concentration and daily intake of inorganic food additives (nitrite, nitrate, and sulfur dioxide), antioxidants (BHA and BHT), a processing agent (propylene glycol), and a sweetener (sodium saccharin) were estimated based on the results of an analysis of 34,489 food samples obtained in official inspections by 106 local governments in Japan in fiscal year 1998. The ratios of mean concentrations of these seven food additives to each allowable limit were 20.0%, 53.9%, 15.5%, 6.2%, 0.4%, 18.5%, and 5.7%, respectively. The daily intakes of these food additives estimated from their concentrations in foods and the daily consumption of foods were 0.205, 0.532, 4.31, 0.119, 0.109, 77.5, and 7.27 mg per person, respectively. These amounts were 6.8%, 0.3%, 12.3%, 0.5%, 0.7%, 6.2%, and 2.6% of the acceptable daily intake (ADI), respectively, when body weight was assumed to be 50 kg. No remarkable differences in the daily intakes of these seven food additives or the ratios to the ADI were observed compared with the results based on the official inspections in fiscal years 1994 and 1996.View full abstractDownload PDF (260K)
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