National Institute for Occupational Safety and Health

“ Determine recovery (R) for each lot of glass fiber filters impregnated with mercuric acetate in the concentration range of interest. Prepare four filters at each of three concentrations plus three media blanks. a. Apparatus for preparing and sampling gas spikes is shown in Figure 1. The apparatus is composed of glass and Teflon. b. Sample at a rate of 0.2 L/min for 100 min. NOTE:
Protect the samples from light. c. Extract the samples (steps 5 through 7) and analyze (steps 10 and 11) . d. Prepare separate recovery graphs for each mercaptan (R vs. μg analyte) . MEASUREMENT: 10. ”

“ Replace the plugs in the filter cassette immediately after sampling. Store protected from light. SAMPLE PREPARATION: 5.
Add 20 mL of 25% (v/v) hydrochloric acid and 5 mL of 1,2-dichloroethane to a 30-mL separatory funnel. Fold sample filter and insert into the neck of a separatory funnel, without allowing the filter to become wet. While seating the stopper, push filter into funnel. 6. ”

“ Separatory funnel, 30-mL.
See SPECIAL PRECAUTIONS. SPECIAL PRECAUTIONS: Store methyl-, ethyl-, and n-butyl-mercaptans separately from flammable and oxidizing materials [5,6] . The analytes are highly flammable and irritating to the eyes. Work in a hood. SAMPLING: 1.
Calibrate each personal sampling pump with a representative sampler in line. 2.
Remove the plugs from the filter cassette immediately before sampling. Connect the cassette to the sampling pump with flexible tubing. Air being sampled should not pass through any hose or tubing before entering filter cassette. 3. ”