National Institute for Occupational Safety and Health

“ After the transfer, rinse the beaker several times with deionized water and add rinsings to funnel for a total volume of 20 mL. Allow the suspension to settle for a few minutes prior to filtration. Do not wash the chimney walls or add deionized water to the chimney after filtration has begun. Rinsing the chimney can disturb the thin layer depo sition. W hen filtration is com plete, k eep vacuum on until filter is dry. Rem ove the filter with forceps and attach it to the sample holder for XRD analysis. ”

“ Determine net normalized intensity for the silver pea k, î Ag, for ea ch m edia blank . Obtain an average value fro the six m edia blank s, Î Aog. NOTE: The analyst is a critical part of this analytical procedure [3] . ”

“ Mount a 37-mm PVC filter on the filtration apparatus. Place several mL 2-propanol on the filter. Turn off the stirrer and shake the bottle vigorously by hand. Imm ediately remove the stopper and withdraw an aliquot (e.g., 2 to 25 mL) by pipet from the center at half-height of the suspe nsion. Do not adjust the volum e in the pipet by expelling part of the suspension. If m ore than the desired aliquot is withdraw n, disc ard th e aliquot in a beak er, rinse an d dry the pipet, and take a new aliquot. ”

“ Filtration apparatus with side-arm vacuum flask and 25- and 37-mm filter holders. 10. Sieve, 10-μm pore size, for wet sieving. 11. Furnace capable of maintaining 1100 °C for 6 h or 1500 °C for 2 h and of tem perature programm ing to 500 °C at 50 °C/min. 12. Crucibles, platinum, with covers. 13. Analytical balance (0.01 m g) . 14. Stirrer, magnetic, with thermally-insulated top. 15. Ultrasonic bath or probe. 16. Pipets, 2-to 25-mL.
NIOSH Manual of Analytical Methods (NMAM) , Fourth Edition SILICA, AMORPHOUS: METHOD 7501, Issue 3, dated 15 March 2003 - Page 3 of 8 EQ UIP M EN T - c on t.: 17. ”

“ Respirable dust: PVC filter (1.a. above) plus cyclone, 10-mm nylon or HigginsDe well (H D) , w ith sam pling head holde r. Holder must keep the cassette, cyclone and coupler togethe r rigidly so that air ente rs on ly at the cyclone inlet. c. Area sample: PVC filter (1.a. above) at 3 L/min. 2. Personal sampling pumps 1 to 3 L/min (total or area) ; 1 .7 L/m in (nylon c yclone ) or 2.2 L/m in (HD cyclone) . 3. Filters, PVC, 25-mm diameter, 0.45-μm pore size. 4. Filters, silver mem brane, 25-m m diame ter, 0.45-μm pore size, available from Sterlitech Corp., 22027 70 th Ave S, Kent, W A 980321911 ”

“ Apply vacuum and rapidly filter the suspension. Do not w ash dow n the sides of the fu nnel after the deposition is in place sinc e this w ill rearrange the m aterial on the filter. Leave va cuu m on until the filter is dry. W hen thoroughly dry, mount the filter in the XRD sample holder. Prepare and analyze standard filters exactly like samples. a. Ash in LT A; redepos it on 25-mm PVC filters (steps 3 through 5) . b. Analyze by XRD (s tep 13) . c. Heat to conve rt amo rphous s ilica to cristobalite ”

“ METHOD 7501, Issue 3, dated 15 March 2003 - Page 2 of 8 EQUIPMENT:
REAGENTS: 1. Am orphous silica standard appropriate to the air sample, i.e., one of the following: a. fumed amorphous silica, grade CAB-OSIL® M-5, ava ilable from Cabot C orp.; www.cabot-corp.com; b. gelled amorphous silica, grade Britesorb® D300 xerogel, available from The PQ Corp., PO Box 840, Valley Forge, PA 19482-0840; www.pqcorp.com; c. diatom ace ous earth amorphous silica, grade Celite 521, available from Fisher Scientific; www.fishersci.com; d. ”