TETRAMETHYL LEAD (as Pb): METHOD 2534, Issue 2, dated 15 August 1994 - Page 3 of 4 a. b.
10.
Remove and discard back sorbent section of a media blank sampler. Inject a known amount (2 to 20 µL) of calibration stock solution directly onto front sorbent section with a microliter syringe. c. Cap the tube. Allow to stand overnight. d. Desorb (steps 5 through 7) and analyze with working standards (steps 11 and 12). e. Prepare a graph of DE vs. µg tetramethyl lead (as Pb) recovered. Analyze three quality control blind spikes and three analyst spikes to ensure that the calibration graph and DE graph are in control.
MEASUREMENT: 11.
12.
Set gas chromatograph according to manufacturer's recommendations and to conditions given on page 2534-1. Inject sample aliquot manually using solvent flush technique or with autosampler. NOTE 1: Under these conditions, t r = 6 min for tetramethyl lead. NOTE 2: If peak area is above the linear range of the working standards, dilute an aliquot of the desorbed liquid with pentane, reanalyze and apply the appropriate dilution factor in calculations. Measure peak area or peak height.
CALCULATIONS: 13.
14.
Determine the mass, µg (corrected for DE) of tetramethyl lead (as Pb) found in the sample front (W f) and back (W b) sorbent sections, and in the average media blank front (B f) and back (B b) sorbent sections. NOTE: If W b > W f/10, report breakthrough and possible sample loss. Calculate concentration, C, of tetramethyl lead (as Pb) in the air volume sampled, V (L):
EVALUATION OF METHOD: Method S384 was issued on April 15, 1977 [2], and validated with generated atmospheres [1,3]. Average recovery was 97.4% ± 6.5% (18 samples) in the range 0.04 to 0.18 mg/m 3 for 24-L samples. No breakthrough occurred after sampling for 240 min at 0.2 L/min from an atmosphere containing 0.312 mg/m 3 tetramethyl lead (as Pb) at 82% RH. Desorption efficiency for eighteen spiked samples in the range 0.89 to 3.6 µg per sample averaged 0.84 with Sr = 0.091. Sample migration between front and back sorbent sections was found to be negligible after storage for 10 days at room temperature.
REFERENCES: [1]
[2] [3]
A. D. Little, Inc. Backup Data Report S384 prepared under NIOSH Contract 210-76-0123 (unpublished, 1976), available as "Ten NIOSH Analytical Methods, Set 3," Order No. PB-275-834 from NTIS, Springfield, VA 22161. NIOSH Manual of Analytical Methods, 2nd ed., Vol. 4, S384, U.S. Department of Health, Education, and Welfare, Publ. (NIOSH) 78-175 (1978). NIOSH/OSHA Occupational Health Guidelines for Chemical Hazards, U.S. Department of Health and Human Services, Publ. (NIOSH) 81-123 (1981), available as Stock #PB83-154609 from NTIS, Springfield, VA 22161.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
