We have developed a quantitative determination method of the concentration of inorganic arsenic in pet foods using a liquid chromatograph-inductively coupled plasma-mass spectrometer (LC-ICP-MS). After adding 2 w/v% TMAH solution to a sample, inorganic arsenic was extracted by heating and the extract was collected by water. The pH of the solution was adjusted, and injected into a LC-ICP-MS to determine the concentration of inorganic arsenic. LC separation was carried out on an ODS column with 10 mmol/L sodium 1-butanesulfonate, 4 mmol/L malonic acid, 4 mmol/L TMAH and 0.05% methanol solution as a mobile phase. A collaborative study was conducted by nine laboratories using dry and wet-type pet foods, formed jerky, dried jerky and biscuit. Dry-type pet food and dried jerky was added with 2 mg/kg of As (III). Wet-type pet food was added with 0.5 mg/kg of As (III). Formed jerky was added with 1 mg/kg of As (III). Biscuit was added with 0.2 mg/kg of As (III). The mean recoveries, repeatabilities and reproducibilities in the form of relative standard deviation (RSD_r and RSD_R), and HorRat, were 95.4% to 98.3%, less than 2.9%, less than 9.1%, and 0.22 to 0.51, respectively.

Aflatoxins (AFs) are known to be oncogenic mycotoxins. This study investigated the mitigation effects of lactic acid bacteria (LAB) isolated from four types of vegetable, cucumber, Chinese cabbage, Japanese radish and eggplant, which are used to make Japanese traditional fermented pickles, on AFs. Using aflatoxin M₁ (AFM₁) binding assay for screening, four representative strains were selected (one from each vegetable) from total 94 LAB strains, based on the highest binding ratio. The ranges of the binding ratio of these representative strains to aflatoxin B₁ (AFB₁), aflatoxin B₂, aflatoxin G₁, aflatoxin G₂ and AFM₁ were 57.5%–87.9% for the LAB strain derived from cucumber, 18.9%–43.9% for the LAB strain derived from Chinese cabbage, 26.4%–41.7% for the LAB strain derived from Japanese radish, and 15.0%–42.6% for the LAB strain derived from eggplant. The strains isolated from cucumber, Chinese cabbage, Japanese radish and eggplant were identified as Lactococcus lactis subsp. lactis, Weissella cibaria, Leuconostoc mesenteroides and Leu. mesenteroides, respectively. An in vitro binding assay of the four strains under acidic conditions showed that the number of living bacteria decreased, while the binding ratio increased in some strains, suggesting that the LAB maintained their capacity to bind aflatoxins even in an environment that imitated the stomach. An in vivo experiment using L. lactis subsp. lactis derived from cucumber revealed that the bacteria significantly inhibited the absorption of AFB₁ into blood. These results showed that the LAB used for Japanese vegetable pickles was an effective binding agent of AFs and suggested that they might play a role in mitigating AF absorption.

Ciguatera poisoning (CP) is one of the most abundant seafood poisonings in the world. CP frequently occurred in the tropical and subtropical Indo-Pacific Ocean and the Caribbean Sea. In Japan, CP cases have been reported annually, from the subtropical regions, including Okinawa Prefecture and Amami Islands, Kagoshima Prefecture. The principal toxins, named ciguatoxins (CTXs), are bio-synthesized by benthic dinoflagellate of genera Gambierdiscus and Fukuyoa. They are bio-transferred herbivorous animals to carnivorous fishes via the food chain.

The Ogasawara Islands comprise more than 30 islands, Mukojima Islands, Chichijima (Bonin) Islands, Hahajima Islands, Iwo Islands, Nishinoshima, Minamitorishima, and Okinotorishima, which locate in the tropical to subtropical regions. The Mukojima Islands, Chichijima Islands, and Hahajima Islands locate approximately the same latitude as Okinawa. The distance from Tokyo is approximately 1,000 km for Chichijima, 1,700 km for Okinotorishima (the southernmost tip of Japan), and 1,900 km for Minamitorishima (the easternmost tip of Japan). These islands exist in a wide range of waters, latitudes from 20°25′ to 27°44′ North and longitudes from 136°04′ to 153° 59′ East. We collected 65 specimens of a grouper, Variola louti, the most frequent species implicated in CP in Japan, from the waters around the Chichijima, Mukojima, and Hahajima islands. The fish flesh specimens were analyzed CTXs using the liquid chromatography-tandem mass spectrometer (LC-MS/MS). While the peak whose retention time is almost identical to that of CTX1B was detected in all specimens on our routine protocol, no 52-epi-54-deoxyCTX1B nor 54-deoxyCTX1B was detected. The peak retention time was quite different from that of CTX1B when re-analyzing by changing the analytical column. Thus, the CTXs in the specimens in the waters of these islands seemed to be undetectable levels.

Cyanogenic glycosides in loquat (Eriobotrya japonica) seeds, which are used in so-called health foods, pose a public concern in Japan due to their potential health risks. Several pretreatment methods, such as the steam distillation and Conway microdiffusion methods, have been established for the determination of cyanogenic glycoside concentrations in foods. However, these methods are time-consuming and have extremely low throughput. Therefore, we developed a simple and rapid method, called the purge method, to analyze cyanide compounds in seed-derived food products. Under this method, the aqueous extract of cyanogenic glycosides is treated with β-glucosidase in a midget impinger, after which the liberated cyanide is purged into an absorbing solution. The concentration of cyanide in the adsorbent is then quantified using 4-pyridinecarboxylic acid-pyrazolone reagent. A single-laboratory method validation study was performed using amygdalin at a concentration of 10 ppm as cyanide ion. The validation parameter results (trueness, 83.9%; repeatability, 1.18%; intermediate precision, 4.67%) indicated that the developed method was suitable, precise and accurate. The purge method was used to analyze cyanide concentrations in commercially available food samples. Of the 10 samples tested (loquat seed powder, apricot kernel powder, and plum seed powder), three samples were found to contain cyanogenic glycosides at concentrations of >10 ppm as hydrogen cyanide, with the highest concentration detected being 861 ppm. These results clearly demonstrated the applicability of our method in determining cyanogenic glycosides in seed-derived food samples.

A rapid, easy and versatile, simultaneous analytical method by LC-MS/MS based on extraction of QuEChERS method (EN 15662:2008) was developed for the determination of residual pesticides in agricultural products. In this method, it allowed to prepare a test solution only dilution without purification using solid phase extraction column. The method was assessed for 210 pesticide residues in 21 kinds of vegetables and fruits at the fortification levels of 0.01 and 0.1 μg/g according to the method validation guideline (Ministry of Health, Labour and Welfare of Japan). As a result, 194 to 210 analytes met the management criteria of the guideline. Thus, the present method could be useful for a rapid simultaneous determination of residual pesticides in agricultural products.

In this study, we developed an analytical method for simultaneous determination of 14 quinolones and 4 tetracyclines in livestock and fishery products using LC-MS/MS. The analytes were extracted from food samples with citrate buffer (containing EDTA)–methanol–acetonitrile (3 : 1 : 1, v/v/v) in the presence of n-hexane, and the extract was purified with an Oasis PRiME HLB cartridge column. It was suggested that this analytical method can also extract analytes from solid samples containing fat by using n-hexane. In addition, using methanol–acetonitrile (3 : 7, v/v) containing 0.1 vol% formic acid as an eluent from the cartridge column, the purification effect could be improved, while minimizing the impairment of the recovery rate. As a result of the validation using six types of food samples, trueness (accuracy) was 70.6%–113.8%, the RSD of repeatability was 9.0% or less, and the RSD of within-laboratory reproducibility was 15.5% or less. Using this approach, the standard values mentioned in the Japanese guideline were successfully met.