RESUMO
In Japan, the use of mothproofing agents [dieldrin and 4,6-dichloro-7-(2,4,5-trichlorophenoxy)-2-trifluoromethylbenzimidazole; DTTB] in textiles is regulated by the Act on the Control of Household Products Containing Harmful Substances. Since official analytical methods for these agents have been in place for approximately 40 years, we developed an improved method in a previous study. In the present study, we validated this method. Accordingly, six laboratories analyzed the sample prepared at 3 µg/g (1/10 of the regulation value) and 30 µg/g (the regulation value). The high accuracy of the results for these samples in almost all the cases (accuracy: 70-120%, repeatability: <10%, reproducibility: <15%), confirmed the validity of the method. In addition, we examined three samples that were distributed before the introduction of the regulation. The analysis results for these samples showed little variation between laboratiories, indicating that our method is also applicable to actual samples. Meanwhile, the quantitative value was clearly lower in one laboratory than in the others. We presumed that the enhanced effect of the sample matrix (matrix effect) on the internal standards in GC-MS analysis was the main cause for this trend. Therefore, we examined the analytical method using polyethylene glycol 300 (PEG) as an analyte protectant. As PEG minimized the GC-MS response difference between the standard solution and the matrix-containing solution, GC-MS analysis with PEG would be useful for matrix effect measurements in this method.
