The preparation of the reference material (RM) for mouse bioassay (MBA) of diarrheic shellfish poisoning (DSP) toxin was attempted. To obtain basic data on the RM, the stability of okadaic acid (OA), which causes DSP, and the method of spiking scallop tissue with OA were examined. Microwave, ultrasonic wave, and UV, which are conventionally used in experiments or may exist in environment, did not affect on the recovery of OA. The recovery rate of OA from thermo treatment at 50-200 °C was examined periodically. Results suggest that temperature has no effect on the recovery rate of OA at temperatures used during conventional analysis and transportation. However, a rapid decrease in recovery was observed during heating at more than 120 °C. In addition, the half-life of OA heated in the range of 120-130 °C was 1 h. OA in acetone solution that was stored in brown vials or dried at the bottom of brown vials was stable during freezing( -35 °C), refrigeration, and storage at room temperature (20 °C) for six months. The titer of OA tested by MBA was stable in stocked samples, but the recovery rate of OA decreased by about 10 % at the HPLC level after 15 months of storage. It was clarified that the recovery rate of OA absorbed in filter paper decreased gradually but the recovery rate of OA was stable under conditions of three-week refrigeration. Samples were distributed to collaborating laboratories and their results of MBA were compared and we did not find any problems on the quality of RM or on the results of MBA quality assurance.

View full abstract

We examined several points and investigations in analytical process of drins. The results were as follows: In the ultrasonic extraction, the addition of some amounts of organic solvent such as alcohol to extractable water was essential for preventing the loss of aldrin; the addition of 5 % sodium chloride water was also useful for preventing the loss of aldrin due to formation of emulsion in the transfer process of drins from methanol to hexane; the sulfuric acid treatment of drins extract degradated drins such as dieldrin and endrin, while the alkarine treatment was useful for the purification of drins, especially in biological samples such as fat tissues; the loss of drins, especially aldrin was observed during the concentration process using nitrogen gas; and the degradation of endrin was found in the determination by GC/MS, which was considered to be due to contamination and/or degradation on top of capillary column and injection port.

View full abstract

Electron Probe Micro Analysis (EPMA) was applied to soil samples which contained high arsenic concentration over soil standard level to identify chemical state and origin of arsenic in the soil. Two dimensional mapping of selected elements including arsenic, iron, sulfur and silicon identified the two types of local distribution of arsenic at high concentration. One type is to contain a high concentration of arsenic, iron and sulfur, indicating the presence of arsenopyrite (FeAsS) in the sample. The other type contained high concentration of iron and arsenic but not with sulfur. The latter seemed to contain iron (III) arsenate which may be secondarily produced through precipitation in the environment after arsenic and iron were dissolved from arsenopyrite by weathering.

View full abstract

We examined the ultrasonic extraction of pesticide residues on strawberries with hexane, acetone, methanol and acetonitrile for extractants. The results showed that analytical values of highly lipophilic pesticides such as diethofencarb, chlorfenapyr and pyridalyl by using the ultrasonic extraction were nearly same as those by the notified analytical method for pesticide residues in farm products. In particular, impurities in hexane solution extracted by ultrasonic wave without further purification were less than those in solution purified by the notified analytical method, indicating the simplified operation in purification process.

View full abstract

Specification and structural characteristics of readily decomposable pesticides in water or acetone by irradiation of ultrasonic waves were investigated. The results exhibited that accelerated decomposition of pesticides in water was found compared with those in acetone and the decomposition rates in water varied widely among pesticides. Relatively high decompositions were observed in pesticides with structures of thiophosphoryl, sulfide and six-membered ring with nitrogen like pyrimidine ring.

View full abstract

We investigated a method for calculating polychlorinated biphenyl (PCB) concentrations in indoor air from the amounts trapped in passive air samplers (PASs) by yarns as trapping materials in order to establish a practical and simple monitoring method. To determine the coefficients required for the calculations, indoor air sampling by yarn PASs and low-volume air samplers was conducted in laboratories over 2 months. The uptake coefficient was determined by dividing the rate of increase in the concentrations of the compounds in the yarn SAS by those atmospheric concentrations measured by a low-volume air sampler. The elimination coefficient was calculated as the ratio of the concentration in the PAS to the atmospheric concentration under equilibrium conditions over 2 weeks. An advantage of this method is that if environmental conditions (air temperature, humidity, wind speed, etc.) do not vary greatly then the atmospheric concentration can be calculated by using a single equation at any place and any time, even when adsorption by the yarn SAS ha not reached equilibrium. The calculated atmospheric concentrations of PCBs were within the range of two to three times the concentrations measured by active air samplers (AASs) at 23 to 28 °C.

View full abstract

Analytical method of mercury for environmental water by ICP-MS was developed. For the determination of Hg, a unstable signal and a large memory effect are serious problems. The addition of Au to the solution such as sample and rinse solution is very effective for alleviation of these problems. Using this method, determination of Hg at the level of pg g ^-1 in the environmental water samples was possible. In addition, pre-concentration by evaporation becomes possible Au addition into the sample. This method was applied to lake waters which were collected from Lake Biwa and tap water in Aomori Prefecture. The concentration of Hg in surface water of Lake Biwa was 3.4 pg g ^-1, and the maximum concentrationin tap water was 3.6 pg g ^-1.

View full abstract