[Studies on rapid multi-residue analysis of pesticides in agricultural products by LC-MS/MS].

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.

[Survey of pesticide residues in imported spices and herbs (1997.4-2011.3)].

A survey of pesticide residues in 313 samples of imported spices and herbs on the Tokyo market from April 1997 to March 2011 was carried out. Thirty-seven kinds of pesticides, including organophosphorus, organochlorine, pyrethroid, carbamate and others, were detected between levels of trace (below 0.01 ppm) and 3.3 ppm from 64 samples. The rate of detection was highest in peel (100%) followed by stem (66.7%), fruit (34.5%), bark (33.3%), flower (31.3%) and leaf (14.7%). No residues were detected in root, seed or whole grass. Organochlorine pesticides were detected in all plant parts. The insecticides were detected in products from all production areas, suggesting that their use is common. Residue levels of these pesticides were calculated as less than 1% of their ADI values, based on the daily intake of spices and herbs. Therefore, these spices and herbs should be safe when consumed in customary amounts.

[Survey of pesticide residues in imported tea (1992.4-2010.3)].

A survey of pesticide residues in 116 imported tea samples on the Tokyo market from April 1992 to March 2010 was carried out. Twenty-two kinds of pesticides, including organophosphorus, organochlorine, pyrethroid and others, were detected at levels between trace (below 0.01 ppm) and 4.0 ppm in 76 samples. The rate of detection was 90% in non-fermented tea, 89% in semi-fermented tea, and 49% in fermented tea. Organophosphorus pesticide was not detected in puer tea, which is fermented with bacteria. The pesticide residues tended to be decreased by a fermentation process. However, organochlorine and pyrethroid pesticides appeared to be chemically stable, so they were still detected in fermented teas. Residue levels of these pesticides were calculated as less than 1% of ADI, except for ethion (45% of ADI) based on the daily intake of tea. Therefore, these teas should be safe when drunk in customary amounts.

[Radioactive cesium in total diet in Hokkaido (2011-2012)].

The level of radioactive cesium (the sum of (134)cesium (Cs) and (137)Cs) was investigated in total diet samples collected from adults living in the Sapporo area, Hokkaido. They were ashed, and examined with a germanium semiconductor detector. The maximum and average radioactivities of cesium in an indivividual's daily food intake were as follows: 1.0 Bq and 0.24 Bq in July 2011, 1.3 Bq and 0.30 Bq in November 2011, 3.9 Bq and 1.0 Bq in February 2012, and 0.34 Bq and 0.12 Bq in July 2012, respectively. The committed effective dose would be 0.022 mSv/year in the case of continued intake of meals containing the maximum cesium concentration.

[Study on rapid analysis method of pesticide contamination in processed foods by GC-MS and GC-FPD].

A simple and rapid method using GC-MS and GC-FPD for the determination of pesticide contamination in processed food has been developed. Pesticides were extracted from a sample with ethyl acetate in the presence of anhydrous sodium sulfate, then cleaned up with a combination of mini-columns, such as macroporous diatomaceous earth, C18, GCB (graphite carbon black) and PSA. Recovery tests of 57 pesticides (known to be toxic or harmful) from ten kinds of processed foods (butter, cheese, corned beef, dried shrimp, frozen Chinese dumplings, grilled eels, instant noodles, kimchi, retort-packed curry and wine) were performed, and the recovery rates were mostly between 70% and 120%. This method can be used to judge whether or not processed foods are contaminated with pesticides at potentially harmful levels.