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Volume 50, Issue 1
Displaying 1-8 of 8 articles from this issue
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Original
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Factors Affecting the Variance of Copy Numbers in Real-time PCR as Estimated from Calibration CurvesTakahiro WATANABE, Tamio MAITANI, Rieko MATSUDA2009 Volume 50 Issue 1 Pages 1-5
Published: February 25, 2009
Released on J-STAGE: March 26, 2009
JOURNAL FREE ACCESSThe distribution interval of calibration curves in real-time PCR was successfully predicted from the variance of the Ct values, and the predicted distribution interval was consistent with the interval of the actual calibration curves. Although the width of the 95% confidence interval at the lower end was about 1%, the copy number estimated from individual calibration curves was distributed over a wider range, and the 95% confidence interval of the estimates of 20 copies was ±40%. The variances of the Ct values at 20 copies were significantly larger than those at higher copy numbers, and this large variation increased the distribution interval of the calibration curves. The variation, however, can be attributed to the probabilistic distribution of copy numbers in the measurement system, and is impossible to reduce by improvement of the analytical methodology. The 95% confidence interval of the calibration curves obtained after omitting 20 copies was decreased and the measurement precision was improved.View full abstractDownload PDF (511K)
Notes
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Hiromi KAWASAKI, Noriko FURUSHO, Chie TATEBE, Hiroki KUBOTA, Tokue YAN ...2009 Volume 50 Issue 1 Pages 6-9
Published: February 25, 2009
Released on J-STAGE: March 26, 2009
JOURNAL FREE ACCESSA simple and rapid method using electron capture detector gas chromatography (GC-ECD) was developed for the determination of hexachlorobenzene (HCB) in Food Red Nos. 104 and 105. The sample was dissolved in water and HCB was extracted with hexane. The GC-ECD operating conditions were as follows: column, InertCap 5 MS/NP (30 m×0.25 mm i. d. with 0.25 μm film thickness); oven temperature, 60°C(1 min)→20°C/min→150°C(10 min)→20°C/min→280°C(5 min); inlet temperature, 260°C; detector temperature, 300°C; carrier gas, nitrogen (constant press 25 psi); inlet mode, splitless. For the evaluation of the method, HCB spiked into R104 and R105 at the levels of 2 μg/g and 5 μg/g was determined in replicate in five laboratories. Mean recoveries of HCB from R104 and R105 were 98.2-103.7%. Repeatability relative standard deviation values were 2.9-6.0% and reproducibility relative standard deviation values were 4.2-9.3%. HORRAT value was less than one. From these results, the validity of this method was confirmed.View full abstractDownload PDF (402K) -
You OKAMOTO, Satoshi TAKATORI, Yoko KITAGAWA, Masahiro OKIHASHI, Naoki ...2009 Volume 50 Issue 1 Pages 10-15
Published: February 25, 2009
Released on J-STAGE: March 26, 2009
JOURNAL FREE ACCESSA rapid and easy multiresidue method for determination of pesticide residues in Chinese dumplings using liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed. Pesticide residues were extracted with ethyl acetate in the presence of anhydrous magnesium sulfate in a disposable tube using a homogenizer. The extract was concentrated and reconstituted in hexane, followed by acetonitrile-hexane partition to remove lipids. The acetonitrile layer was purified with a double-layered cartridge column (graphite carbon black/primary secondary amine silica gel). After removal of the solvent, the extract was resolved in methanol/water and analyzed with LC-MS/MS. Recovery tests of 99 pesticide residues from Chinese dumpling were performed at 20 and 100 ng/g, and 72 pesticides exhibited acceptable recoveries (70-120%) with low relative standard deviations (<20%) at both concentrations. The time for sample preparation with 12 samples to test solutions was approximately 6 hr. This method could be useful for determination of pesticide residues in the Chinese dumplings.View full abstractDownload PDF (491K) -
Atsuko TADA, Naoki SUGIMOTO, Kyoko SATO, Takumi AKIYAMA, Masaharu ASAN ...2009 Volume 50 Issue 1 Pages 16-21
Published: February 25, 2009
Released on J-STAGE: March 26, 2009
JOURNAL FREE ACCESSJamaica quassia extract is a natural bittering agent used as a food additive in Japan. The main constituents of the extract have already been reported to be quassin and neoquassin. In this study, the differences in composition of the constituents among four Jamaican quassia extract products were analyzed by LC/MS. The results showed that the four products have similar compositions of their minor constituents, as well as their main constituents. We isolated four of the minor constituents that were commonly included in the four products, and identified them as 11-dihydro-12-norneoquassin, canthin-6-one, 4-methoxy-1-vinyl-β-carboline and 4,9-dimethoxy-1-vinyl-β-carboline. The List of Existing Food Additives in Japan mentions that Jamaica quassia (Picrasma excelsa) is the original plant from which Jamaica quassia extract is produced. However, we presume that Jamaica quassia extract may actually be made from appropriate plants other than Picrasma excelsa, since P. excelsa is listed as an endangered species by the International Union for Conservation of Nature and Natural Resources. We prepared hot water extracts from two other species of plants, Quassia amara (American quassia, Surinam quassia) and P. quassioides (‘Nigaki’ in Japanese), and investigated their constituents by LC/MS. The results showed that the compositions of the constituents in the Jamaica quassia extract products resembled those in the extract derived from Q. amara. These findings suggest that Jamaica quassia extract products are probably made from Q. amara.View full abstractDownload PDF (796K) -
Shigeto TANIYAMA, Yuta ISAMI, Takuya MATSUMOTO, Yuji NAGASHIMA, Tomohi ...2009 Volume 50 Issue 1 Pages 22-28
Published: February 25, 2009
Released on J-STAGE: March 26, 2009
JOURNAL FREE ACCESSFrom September 2007 to January 2008, a total of 66 specimens of 7 gastropod species, Nassarius (Alectrion) glans (n=22), Bufonaria rana (n=11), Ficus subintermedia (n=10), Stellaria (Onustus) exutus (n=8), Tonna luteostoma (n=7), Hemifusus tuba (n=4) and Semicassis bisulcata persimilis (n=4), were collected from Tachibana Bay, Nagasaki Prefecture, Japan, and their toxicity was determined by mouse bioassay. Among the gastropods tested, all N. glans specimens were toxic, whereas no other species showed toxicity of more than 5 MU/g. The toxicity scores of N. glans were very high; 48-2,730 MU/g(775±615 MU/g)in the muscle, and 16-10,200 MU/g(1,490±2,530 MU/g)in the viscera, including digestive gland. Interestingly, toxin was localized in the muscle in 13 of 22 specimens, where the total toxicity of the muscle (725-9,860 MU/individual) was 5.9-110 times higher than that of the viscera. LC/MS analysis demonstrated that the toxin of N. glans consisted mainly of TTX, which accounting for about 60-65% of the total toxicity. As for the remaining toxicity, participation of 11-oxoTTX was suggested. No paralytic shellfish poison was detected in HPLC-FLD analysis.View full abstractDownload PDF (1083K)
Reports
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Rieko MATSUDA, Takahiro WATANABE, Atsuko IKARASHI, Yuko SHIRAMASA, Tam ...2009 Volume 50 Issue 1 Pages 29-33
Published: February 25, 2009
Released on J-STAGE: March 26, 2009
JOURNAL FREE ACCESSThe concentrations of nitrates in total diet samples prepared at 11 places were determined according to the market basket method, and the daily intake of nitrates was estimated based on the analysis results. The mean estimated daily intake of nitrates was 200 mg/man/day (4.0 mg/kg/day) and exceeded the ADI (3.7 mg/kg/day) set by the JECFA by 8%. The principal sources of the nitrates were colored vegetables (7th food group) and other vegetables, seaweeds and mushrooms (8th food group), and the intake from these food groups accounted for more than 80% of the total intake. The reported concentrations of nitrates in individual foods and the estimated daily intake of these foods indicate that the intake of nitrates from spinach accounts for 38% of the ADI, that from Chinese cabbage for 10%, and that from Japanese radish for 20%.View full abstractDownload PDF (404K) -
Yukiko HARA-KUDO, Kosuke TAKATORI2009 Volume 50 Issue 1 Pages 34-40
Published: February 25, 2009
Released on J-STAGE: March 26, 2009
JOURNAL FREE ACCESSAerobic bacteria counts and contamination with Salmonella were investigated in a total of 1,327 samples of commercial liquid egg in 1992-2002. Salmonella was isolated from 8.1% of the samples, and Salmonella contamination was found in 1.7% of even the pasteurized liquid egg samples. The major Salmonella serotype was Enteritidis from more than 50% of the contaminated liquid egg samples. In addition, the aerobic bacteria counts in Salmonella-positive liquid eggs were significantly higher than those of Salmonella-negative samples. However, Salmonella was detected in liquid egg in which the aerobic bacteria counts were in the range of 102 to 106 cfu/g. Furthermore, foodborne outbreaks of Salmonella infections associated with liquid egg were analyzed. Liquid eggs should be carefully treated to avoid the possibility of Salmonella contamination. Adequate supply of pasteurized liquid eggs and controls to prevent re-contamination are needed.View full abstractDownload PDF (393K) -
Taichi OGUCHI, Mari ONISHI, Yukie CHIKAGAWA, Takashi KODAMA, Emiri SUZ ...2009 Volume 50 Issue 1 Pages 41-46
Published: February 25, 2009
Released on J-STAGE: March 26, 2009
JOURNAL FREE ACCESSGenetically modified (GM) sugar beets have been bred for use as food and animal feed. To evaluate the applicability of GMO analyses to beet sugar products, we investigated residual DNA in eight sorts of in-process beet sugar samples and commercial beet sugar products. Polymerase chain reaction (PCR) analyses with taxon-specific primers indicated that sugar beet DNA was degraded at an early stage of sugar processing, and no PCR amplification was detected from the investigated sugar products because of low DNA recovery and/or PCR inhibition.View full abstractDownload PDF (578K)
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