Page:NIOSH Manual of Analytical Methods - 6007.pdf/3

NICKEL CARBONYL: METHOD 6007, Issue 2, dated 15 August 1994 - Page 3 of 4 SPECIAL PRECAUTIONS: None. SAMPLING: 1. 2. 3. 4.

Calibrate each personal sampling pump with a representative sampler in line. Break the ends of the sampler immediately before sampling. Attach prefilter. Attach sampler to personal sampling pump with flexible tubing. Sample at an accurately known flow rate between 0.05 and 0.2 L/min for a total sample size of 7 to 80 L. Cap the samplers. Pack securely for shipment.

SAMPLE PREPARATION: 5. 6. 7.

Place the front and back sorbent sections of the sampler tube in separate vials. Discard the glass wool and foam plugs. Discard prefilter or analyze for particulate Ni. Add 1.0 mL 3% HNO 3 to each vial. Cap each vial. Allow to stand 30 min in an ultrasonic water bath.

CALIBRATION AND QUALITY CONTROL: 8.

9.

10.

Calibrate daily with at least six working standards. a. Add known amounts of calibration stock solution to 3% HNO 3 in 10-mL volumetric flasks and dilute to the mark. Use serial dilutions as needed to obtain Ni 2+ concentrations in the range 0.01 to 0.6 µg/mL. Store in polyethylene bottles and prepare fresh daily. b. Analyze with samples and blanks (steps 11 through 13). c. Prepare calibration graph (absorbance vs. µg Ni 2+). Determine desorption efficiency (DE) at least once for each lot of sorbent used for sampling in the range of interest. Prepare three tubes at each of five levels plus three media blanks. a. Remove and discard back sorbent section of a media blank sampler. b. Inject a known amount (2 to 20 µL) of calibration stock solution, or a serial dilution thereof, 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 through 13). e. Prepare a graph of DE vs. µg Ni 2+ 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. 13.

Set spectrophotometer and graphite furnace according to manufacturer's recommendations, conditions given on page 6007-1, and the following: a. Inert gas flow: increased sensitivity if flow is interrupted during atomization. b. Wavelength: either 232 nm (more sensitive) or 341.5 nm. c. Dry cycle: 30 sec at 110 °C; longer time and ramp program may be needed for aliquots >20 µL. d. Ash (char) cycle: 15 sec at 800 °C. e. Atomize cycle: 10 sec at 2700 to 3000 °C; atomization is too slow for reproducible results below 2600 °C; "maximum power" feature will increase sensitivity. Inject sample aliquot manually or with autosampler. Measure peak height. Analyze a series of standards before and after each set of samples and analyze one mid-range standard after each ten samples. Analyze all solutions, including sorbent tube blanks and reagent blanks, in triplicate. NOTE 1: Peak occurs about 3 sec after start of atomize cycle. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94