EST RO GE NIC C OM PO UN DS: M ETH OD 5044, Issue 1, dated 1 5 Ma rch 2003 - Page 3 of 6 12. Determine the desorption efficiency and recovery in the range of interest for each lot of filters used for sampling. a. Prepare four tubes at each of three levels plus three media blanks. b. Add known amounts of the analyte or analyte mixture in methanol to the filters. c. Allow to stand $2 hr for solvent evaporation. d. Prepare sam ples (steps 6 through 1 0) and ana lyze together with standards (steps 15 and 16 ). e. D ete rm ine rec overy. 13. Analyze three quality control blind spikes and three analyst spikes to ensure that the calibration graph and re covery graph are in control.
MEASUREMENT: 14. Set HPLC according to manufacturer's instructions and conditions on page 5044-1. 15. Inject sam ple aliquot m anually or with autosam pler. 16. Measure peak areas.
CALCULATIONS: 17. Determine the mass in :g of analytes found on the sample filter, W , and on the average blank filter, B. 18. Calculate conce ntration, C, of analytes in the air volum e sam pled, V (L):
NO TE : :g/L / m g/m 3
EVALUATION OF METHOD: This method has been used to analyze field-generated wipe samples [2]. It wa s not evaluated with laborato rygenerated air samples. LOD/LOQ, extraction efficiency, sam pling stability and storage s tability studies were performed with laboratory-spiked filters. LOD/LOQ values (in :g/filter) for $-Estradiol were 0.8/2.5; for Estrone, 0.2/0.5; for Progesterone, 0.5/1.7; and for $-Estradiol 3-Benzoate, 0.5/1.7. Extraction efficiency for $-Estra dio l ra nged from 94 to 103% ; for E strone, 95 to 104% ; for Progesterone; 97 to 102% ; for $-Estradiol 3-Benzoate, 95 to 101%. An additional recovery study using W ash 'n Dri® wipes gave extraction efficiencies of 97 to 100%. The sta bility of the analytes on the filter m edia (s tatic efficiency) was evaluated by drawing air through spiked filters. Reco veries ranged from 94 to 102% for $-Estradiol; for Estrone, from 96 to 101%; for Progesterone, from 99 to 102% ; and for $-Estra dio l 3-B enzoate, from 92 to 101% . Reco very after 30-da y storage a t 25 °C was 93% for $-Estradiol, 94% for Estrone, 98% for Progesterone, and 111% for $-Estradiol 3-Benzoate.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition
