National Institute for Occupational Safety and Health

“ Calibration standards have been prepared and evaluated up to a level of 324 μg/ml. This amount equates to 648 μg/sample for field samples.
This method was developed to be used in conjunction with NMAM 5601 for the analysis of thiophanate-methyl, carbendazim, and captan. In laboratory prepared samples, it was found that the recoveries of thiophanate-methyl may decrease and those of carbendazim may increase due to chemical interactions and the decomposition of thiophanate-methyl to carbendazim [2] . ”

“ Thiophanate-methyl stock solution, 10 mg/mL. Prepare in acetonitrile and store in refrigerator. TEA-PO4 preservative. Dissolve 1.4 mL of TEA in 90 mL of deionized water in a 100-mL volumetric flask. Add phosphoric acid to lower pH to 7.0 ± 0.1 as indicated by a calibrated pH meter. Bring volume to 100 mL with water. Keep tightly capped and refrigerated. Solution stable for 12 months. Mobile phase A. Combine 20 mL of n-propanol and 2.8 mL TEA in a 1-L volumetric flask and bring to volume using deionized water. Adjust pH to 7.0 ± 0.1 with phosphoric acid using a pH meter. ”

“ Solvents: Avoid skin contact and open flame. Use in a hood. Phosphoric acid: Avoid skin contact. See Note 1.
SAMPLING:
1. Calibrate each personal sampling pump with representative sampler in line.
2. Connect the sampler to the personal sampling pump with flexible tubing. Place sampler vertically, with the large end down, in the breathing zone. ”