CADMIUM and compounds, as Cd: METHOD 7048, Issue 2, dated 15 August 1994 - Page 2 of 4 EQUIPMENT:
REAGENTS: 1. 2. 3. 4.
5. 6. 7.
Nitric acid, conc., ultrapure. Hydrochloric acid, conc., ultrapure. Hydrochloric acid, 0.5 N. Add 41.5 mL conc. HCl to water; dilute to 1 L. Calibration stock solution, 100 µg Cd/mL.* Commercially available or dissolve 0.100 g Cd metal in minimum volume of (1:1) HCl. Dilute to 1 L with 0.5 N HCl. Distilled-deionized water. Air, filtered. Acetylene.
1. Sampler: cellulose ester membrane filter, 0.8-µm pore size, 37-mm diameter; in cassette filter holder. 2. Personal sampling pump, 1 to 3 L/min, with flexible connecting tubing. 3. Atomic absorption spectrophotometer with an air-acetylene burner head , cadmium hollow cathode lamp, and background correction. 4. Regulators, 2-stage, for air and acetylene. 5. Beakers, Phillips, 125-mL, or Griffin, 50-mL, with watchglass covers.* 6. Volumetric flasks, 25- and 100-mL.* 7. Micropipets, 5 to 300 µL.* 8. Hotplate, surface temperature 400 °C.
See SPECIAL PRECAUTIONS.
Clean with conc. nitric acid and rinse thoroughly before use.
SPECIAL PRECAUTIONS: Perform all acid digestions in a fume hood. Cadmium compounds are very toxic and should be considered carcinogens [3,7]. Handle with extra care.
SAMPLING: 1. 2.
Calibrate each personal sampling pump with a representative sampler in line. Sample at an accurately known flow rate between 2 and 3 L/min for 15 min (30 to 45 L) for ceiling measurements, or at 1 to 3 L/min for a total sample size of 25 to 1500 L for TWA measurements. Do not exceed a filter loading of ca. 2 mg total dust.
SAMPLE PREPARATION:
3. 4. 5. 6. 7. 8. 9. 10.
NOTE: The following sample preparation gave quantitative recovery (see EVALUATION OF METHOD). Steps 4 through 9 of Method 7300 or other quantitative ashing techniques may be substituted. Open the cassette filter holders and transfer the samples and blanks to separate clean beakers. Add 2 mL conc. HNO 3, cover with a watchglass, and heat on hotplate (140 °C) until the volume is reduced to ca. 0.5 mL. Start reagent blanks at this point. Repeat 2 more times using 2 mL conc. HNO 3 each time. Add 2 mL conc. HCl, cover with a watchglass, and heat on hotplate (400 °C) until the volume is reduced to ca. 0.5 mL. Repeat 2 more times using 2 mL conc. HCl. Do not allow the solution to go to dryness at any point. Cool solution and add 10 mL distilled water. Transfer the solution quantitatively to a 25-mL volumetric flask. Dilute to volume with distilled water.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
