For easy and rapid DNA extraction from processed foods, we developed a new silica membrane-based DNA extraction method. DNA extraction conditions suitable for processed foods were examined based on an existing DNA extraction kit for raw grain materials, GM quicker 2. Twenty microliters of proteinase K solution (20mg/ml) was used for cell lysis and the digestion was carried out at 65℃ for 30min. In addition, 200μl for wet processed foods or 400μl for dry processed foods of 2.0 M potassium acetate (pH 3.7) and 600μl of 8.0 M guanidine hydrochloride were adopted as buffers to achieve good DNA recovery from cell lysates. The novel method was compared to four conventional methods using six kinds of processed foods as analytical samples, i.e., roasted soybean flour, soy milk, miso, canned whole kernel sweet corn, corn snack and dried soup mix. The developed method showed wide applicability to various process foods and it gave sufficient amounts of DNA with high purity. Also, the method was highly user-friendly because of the short handling time, the small number of pipette operations and non-use of toxic organic solvents. The method would be practically used for food testing to detect genetically modified organisms, allergens, pathogenic microorganisms and so on.

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Rapid method combining microwave digestion and ICP-MS analysis was developed for the simultaneous determination of seven harmful elements (Cd, Pb, Ba, As, Hg, Cr and Ag) in food contact plastics, the former four elements are regulated by the Japanese Food Sanitation Law. After microwave digestion of 100mg of milled sample with HNO₃, digested solution was diluted and then applied to ICP-MS. The recoveries were mainly more than 80% using the standard and test solutions prepared by the equalized HNO₃ concentrations with the internal standards. This new method was also valid for analysis of Pb in polypropylene containing barium sulfate which showed very low recovery by dry ash method adopted in Japanese official method.

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A method for the determination of triethylamine and tributhlamine in polycarbonate products was developed using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The sample was dissolved with dichloromethane, and the polymer was precipitated by addition of methanol. In order to avoid volatilization of triethylamine and tributylamine during evaporation of dichloromethane and methanol, 2% formic acid was added to the methanol mixture. After evaporation, triethylamine and tributylamine were determined by LC-MS/MS. Recoveries of triethylamine and tributylamine in polycarbonate products at the level of 1μg/g were 96,101% respectively, and the limits of quantification were 0.05μg/g in samples.

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Dapoxetine (1) and flibanserin (2) have pharmaceutical effects against premature ejaculation (PE) and hypoactive sexual desire disorder (HSDD), respectively. In international markets, these compounds have been reported as illegal additives in health foods for which tonic effects are implicitly indicated. Therefore, we performed LC-PDA-MS analysis in preparation for the distribution of illegal health foods containing these compounds in Japan. Compounds 1 and 2 were completely separated at r.t. 11.3 and 10.7 min, respectively, under the conditions described as the analytical method for udenafil by the Ministry of Health, Labour and Welfare, Japan. Their spectroscopic data (UV and MS) corresponded to the literature data. Subsequently, we added authentic dapoxetine and flibanserin to an extract of the food supplements with or without an ED treatment agent including sildenafil and tadarafil etc., and then these sample solutions were analyzed using the proposal method. As a result, each compound was completely separated on the UV and mass chromatograms. This study provides useful data for the surveillance of unapproved/unlicensed drugs in health food products.

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Many of Japanese consumers fear and avoid gene modified organisms (GMOs) although they don't know any technology, advantage and disadvantage of it. In addition, a lot of them don't know under 5% of contamination of GMOs to agricultural commodity is considered "unintended commingling" and allows to sign "Non-GMO" to products when they were treated under the identity preserved (IP) handling. In fact not exceeding 5% commingling of the Roundup Ready Soybeans (RRS) from soybean curds were reported in some areas around Japan. However there is not the evidence of the commingling of RRS to Soybean curds distributed at Nagano Prefecture. From these evidences, RRS content rates were examined almost Kinugoshi-tofu, soft and smooth soybean curds, which were sold at Matsumoto-city and its suburbs, Nagano pref., from May 2011 to April 2012. Genome DNA of soybean and RRS specific gene were extracted by silica-based membrane methods arranged for isolation DNA from tofu. RRS and internal control gene, Le1 were detected by realtime PCR-system. 101 samples of soybean curds were examined. The data showed 34 samples (33.7% of 101 samples) contained RRS. All of RRS contents were trace amount and lower than 5%, that was Consumer Affairs Agency's guideline.

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[in Japanese]

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