The contamination of processed vegetable foods with genetically modified tomatoes was investigated by the use of qualitative PCR methods to detect the cauliflower mosaic virus 35S promoter (P35S) and the kanamycin resistance gene (NPTII). DNA fragments of P35S and NPTII were detected in vegetable juice samples, possibly due to contamination with the genomes of cauliflower mosaic virus infecting juice ingredients of Brassica species and soil bacteria, respectively. Therefore, to detect the transformation construct sequences of GM tomatoes, primer pairs were designed for qualitative PCR to specifically detect the border region between P35S and NPTII, and the border region between nopaline synthase gene promoter and NPTII. No amplification of the targeted sequences was observed using genomic DNA purified from the juice ingredients. The developed qualitative PCR method is considered to be a reliable tool to check contamination of products with GM tomatoes.
Rapid multi-residue analysis of pesticides in agricultural products was studied by using LC-MS/MS. Pesticide residues in 10 g of homogenized agricultural products were extracted with 30 mL of acetonitrile and salted out with 4 g of anhydrous magnesium sulfate and 1 g of sodium chloride in the presence of citrate salts for buffering in a disposable tube. Co-extractives were removed by use of our original triple layered column (C18/GC/PSA; 60/30/60 mg). According to the method validation guideline of the Ministry of Health, Labour and Welfare of Japan, we conducted recovery tests in 5 kinds of agricultural products (brown rice, kiwi, cabbage, sweet potato and spinach) spiked with 60 pesticides at the level of 0.01 or 0.1 μg/g. Each concentration of pesticide spiked was extracted from 2 samples per day on 5 days. Pesticides in the test solution were determined by two types of LC-MS/MS using scheduled MRM. Using this method, 58 out of 60 pesticides satisfied the guideline criteria in brown rice, 59 in kiwi, 55 in cabbage, 55 in sweet potato and 56 in spinach. This method is applicable for routine examination of pesticide residues in agricultural products.
The contaminants in a beverage product that had been reported to have a strange taste were identified. By comparative analysis with the normal product using liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (LC-QTOF-MS), six unknown compounds were detected in the total ion current chromatograms of the product in question. Detailed analysis of the mass spectra and product ion spectra of these compounds strongly suggested that the compounds were capric acid diethanolamide, lauric acid diethanolamide, myristic acid diethanolamide, lauryl dimethylaminoacetic acid, lauryl sulfate, and lauric acid, all of which are surfactants commonly used as ingredients of household detergents and shampoos. We searched commercially available detergent products to check for the presence of these six surfactants, and identified products that might have been intentionally or unintentionally mixed into the beverage product after opening.
Based on the Japanese Food Sanitation Law, the performances of official and alternative material test methods for cadmium (Cd) and lead (Pb) in food contact plastics were compared. Nineteen laboratories participated to an interlaboratory study, and quantified Cd and Pb in three PVC pellets. in the official method, a sample is digested with H2SO4, taken up in HCl, and evaporated to dryness on a water bath, then measured by atomic absorption spectrometry (AAS) or inductively coupled plasma-optical emission spectrometry (ICP-OES). Statistical treatment revealed that the trueness, repeatability (RSDr) and reproducibility (RSDr) were 86–95%, 3.1–9.4% and 8.6–22.1%, respectively. The values of the performance parameters fulfilled the requirements , and the performances met the test specifications. The combination of evaporation to dryness on a hot plate and measurement by AAS or ICP-OES is applicable as an alternative method. However, the trueness and RSDr were inferior to those of the official method. The performance parameters obtained by using the microwave digestion method (MW method) to prepare test solution were better than those of the official method. Thus, the MW method is available as an alternative method. Induced coupled plasma-mass spectrometry (ICP-MS) is also available as an alternative method. However, it is necessary to ensure complete digestion of the sample.
According to “The validity evaluation guideline of the testing methodology on the residual pesticides in food” of the Ministry of Health, Labour and Welfare of Japan, we carried out validity evaluation of a simultaneous analysis method for residual pesticides in various products with the QuEChERS method using a C18 mini column and/or an EnviCarb/PSA mini column for purification. Multi-ingredient simultaneous analysis with high sensitivity in a short time was achieved with LC-MS/MS. Validation was achieved for 269 pesticides among 302 pesticides in eight kinds of fruit, vegetables, and brown rice and 204 pesticides among 233 pesticides in oolong tea. Finally, 151 pesticides in oolong tea and from 234 to 259 pesticides in fruit, vegetables, and brown rice met the values specified in the guideline.
A multi-residue method for 122 pesticides in agricultural products was validated in accordance with Japanese guidelines for residual agricultural chemicals in food. The sample was extracted with acetonitrile. Co-extractives were removed by GPC-graphitized carbon column SPE, followed by silica gel/PSA cartridge column SPE. The pesticides in the test solution were determined by LC-MS/MS using scheduled MRM in combination with polarity switching. Validation tests were performed on spinach, brown rice, soybean, orange and tomato fortified at 0.01 and 0.1 μg/g. The pesticides at each level were analyzed in two samples per day on five different days. In conclusion, among 122 pesticides tested for each level, 121 pesticides (but not disulfoton) were found to meet all of the guideline criteria.