Page:NIOSH Manual of Analytical Methods - 7502.pdf/2

 ZINC OXIDE: METHOD 7502, Issue 2, dated 15 August 1994 - Page 2 of 5 REAGENTS: 1. 2. 3. 4.

EQUIPMENT:

Zinc oxide, ACS reagent grade. Average particle size between 0.5 µm and 10 µm. 2-Propanol. Desiccant. Glue or tape for securing filters to XRD holders.

1. Sampler: polyvinyl chloride (PVC) or PVC-acrylonitrile membrane filters, 25-mm diameter, 0.8-µm pore size; three-piece filter cassette. NOTE: An extension cowl on the filter cassette is desirable to produce a more uniform deposit and to prevent contamination of the open-face filter during sampling. 2. Personal sampling pump, 1 to 3 L/min, with flexible connecting tubing. 3. High-volume sampling pump, 10 L/min. 4. X-ray powder diffractometer equipped with copper target X-ray tube and scintillation detector. 5. Reference specimen (mica, Arkansas stone or other stable standard) for data normalization. 6. Filtration apparatus and side arm vacuum flask with 25-mm filter holders. 7. Analytical balance (0.01 mg); magnetic stirrer; ultrasonic bath or probe; volumetric pipettes and flasks; desiccator; reagent bottles with ground glass stoppers; drying oven; polyethylene wash bottle.

SPECIAL PRECAUTIONS: none.

SAMPLING: 1. 2. 3.

Calibrate each personal sampling pump with a representative sampler in line. Sample open-face at 1 to 3 L/min for a total sample size of 10 to 400 L. Do not exceed 2 mg total dust loading on the filter. Take a high-volume (4000 L) air sample using a clean sampler and high-volume sampling pump in the same area as the personal sample(s) for qualitative identification.

SAMPLE PREPARATION: 4.

Mount field samples and blanks on XRD sample holders using appropriate methods for securing the sample to the XRD holder.

CALIBRATION AND QUALITY CONTROL: 5.

6.

Prepare two suspensions of ZnO in 2-propanol by weighing 10 mg and 50 mg of the dry powder to the nearest 0.01 mg. Quantitatively transfer to a 1-L glass-stoppered bottle using 1 L 2-propanol. Suspend the powder in 2-propanol by using an ultrasonic probe or bath for 20 min. Immediately move the flask to a magnetic stirrer with thermally-insulated top and add a stirring bar to the suspension. Cool the solution to room temperature before withdrawing aliquots.

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