National Institute for Occupational Safety and Health

“ Calculate R (mg recovered/mg added) .
MEASUREMENT: 9. 10.
Establish chromatographic conditions listed on page 5001-1 for either 2,4-D or 2,4,5-T. Inject 50 μL of sample in duplicate. Rinse and dry the syringe between samples. NOTE 1: The analyte is the chlorinated phenoxyacetate, whether the air sample contained salts or free acid forms of 2,4-D and 2,4,5-T. NOTE 2: Esters of 2,4-D and 2,4,5-T will not elute from the HPLC column and may, if present in large amounts, degrade the HPLC column. Protect the main column with a precolumn of Zipax SAX if esters are known to be present. ”

“ Filter the sample. a. Pour the sample solution into a 20-mL syringe which is fitted with a 5-μm PTFE filter. b. Filter the sample into a clean vial. c. Clean the PTFE filter by backflushing with methanol. Rinse the syringe and plunger with methanol. Dry with air or nitrogen.
CALIBRATION AND QUALITY CONTROL: 7.
8.
Calibrate daily with at least five working standards. a. Dilute aliquots of calibration stock solution to 10 mL with methanol in volumetric flasks. b. Analyze working standards (steps 9 and 10) . c. Prepare calibration graph (peak area vs. mg 2,4-D or mg 2,4,5-T) . ”

“ Criteria for a Recommended Standard...Occupational Exposure During Manufactur and Formulation of Pesticides, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 78-174 (1978) .Welfare, Publ. (NIOSH) 79-141 (1979) . [5] NIOSH Research Report-Development and Validation of Methods for Sampling and Analysis of Workplace Toxic Substances, U.S. Department of Health and Human Services, Publ. ”