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 THIRAM: METHOD 5005, Issue 2, dated 15 August 1994 - Page 3 of 3 CALCULATIONS: 11. 12.

Read the mass, mg, of Thiram found in the sample filter (W f) and top rinse (W t) and in the average media blank (B) from calibration graph. Calculate the concentration of Thiram, C (mg/m 3), in the air volume sampled, V (L):

EVALUATION OF METHOD: Method S256 was issued on June 8, 1979 [2], and validated by collecting 18 samples (six each at one-half, one and two times the OSHA standard) from dynamically-generated test atmospheres using Thiram 65 (65% Thiram; Mayer Chemical Co.), as well as a set of six samples which was stored at room temperature for seven days to establish stability [1,4]. The stored sample results were within 2.1% of samples analyzed after one day, indicating adequate storage stability for seven days. Eighteen more samples were spiked directly (six each at one-half, one and two times the OSHA standard). The pooled relative standard deviation for these three sets of samples was found to be 0.012. The average recovery for all three levels was 99.8%; therefore, there is no bias for this method. The pooled relative standard deviation for the three sets of samples collected from test atmospheres was 0.022. Test atmospheres at 12 mg/m 3 Thiram were sampled with PTFE filters followed by bubblers containing acetonitrile; no detectable Thiram (LOD = 0.005 mg) was found in the bubblers indicating that vapor pressure of Thiram was insignificant.

REFERENCES: [1] [2] [3] [4] [5]

[6]

Backup Data Report S256, NIOSH Contract 210-76-0123, available as Order No. PB 81-244634 from NTIS, Springfield, VA 22161. NIOSH Manual of Analytical Methods, 2nd. ed., V. 5, S256, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 79-141 (1979). Ibid, V. 1, P&CAM 228, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-157-A (1977). Failure Report S256, NIOSH Contract CDC-99-74-45 (unpublished, 1976). Criteria for a Recommended Standard...Occupational Exposure During Manufacture and Formulation of Pesticides, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 78-174 (1978). 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. (NIOSH) 80-133 (1980).

METHOD REVISED BY: Yvonne T. Gagnon, NIOSH/DPSE; S256 originally validated under NIOSH Contract 210-76-0123.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94