Page:NIOSH Manual of Analytical Methods - 7102.pdf/3

 BERYLLIUM and compounds, as Be: METHOD 7102, Issue 2, dated 15 August 1994 - Page 3 of 3 CALIBRATION AND QUALITY CONTROL: 9.

10.

Calibrate daily with at least six working standards over the range 0.005 to 1 µg Be per sample. a. Use serial dilutions of known amounts of calibration stock solution in 2% Na 2SO 4/ 3% H 2SO 4 to prepare working standards. Store in polyethylene bottles. Stable at least four weeks. b. Analyze together with samples and blanks (steps 11 and 12). NOTE: Analyze working standards alternately with the samples to compensate for the increasing Be signal as the graphite tube ages. Analyze three quality control blind spikes and three analyst spikes.

MEASUREMENT: 11. 12.

Set spectrophotometer and graphite furnace according to manufacturer's recommendations and to conditions on page 7102-1. Inject 10-µL aliquots of samples into graphite tube. Record absorbance (peak height mode).

CALCULATIONS: 13. 14.

Read absorbance of samples, A; average media blanks, A b; average sulfate reagent blanks, A r; and working standards, A s. Using the working standard, C s (µg/mL), analyzed adjacent to the sample of interest, calculate concentration, C (µg/m 3), of Be in the air volume sampled, V (L):

EVALUATION OF METHOD: This method was evaluated using NTIS Standard Reference Material No. 2675 for Be over the range of 0.1 to 0.4 µg Be/filter (equivalent to one-half to two times the OSHA PEL). Beryllium recovery was 98.2% with a measurement precision, Sr, of 0.008 [2]. This method is an improvement of S339 [3], which was validated over the range of 2.68 to 11.84 µg/m 3 using a 40-L sample. Mean recovery was 106.9% with overall precision of 0.064 [1].

REFERENCES: [1] Documentation of the NIOSH Validation Tests, S339, U.S. Department of Health, Education and Welfare, Publ. (NIOSH) 77-185 (1977). [2] NIOSH Manual of Analytical Methods, 2nd ed., V. 5, P&CAM 288, U.S. Department of Health, Education and Welfare, Publ. (NIOSH) 79-141 (1979). [3] Ibid., V. 3, S339, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 77-157-C (1977). [4] Criteria for a Recommended Standard...Occupational Exposure to Beryllium, U.S. Department of Health, Education and Welfare, Publ. (NIOSH) 72-10268 (1972); and as revised in August, 1977 in NIOSH testimony at OSHA hearing.

METHOD REVISED BY: Mary Ellen Cassinelli, NIOSH/DPSE; S339 validated under NIOSH Contract CDC-99-74-45.

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