Page:NIOSH Manual of Analytical Methods - 9102.pdf/2

 ELEM ENT S O N W IPES: M ETH OD 9102, Issue 1, dated 1 5 Ma rch 2003 - Page 2 of 5 REAGENTS:

EQUIPMENT:

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Nitric acid (HNO 3), con c., ultra p ure.* Perchloric acid (HCLO 4), con c., ultra p ure.* Ca libration s tock solutions, 1000 µg/m L comm ercially available, or prepared per instrument manufacturer’s recomm endation (see step 20 ). Dilution acid, 4:1 HNO 3:HC IO 4. Mix 4 volumes conc. HNO 3 with 1 volume conc. HC IO 4. Argon. Distilled, de-ionized water.
 * See SPECIAL PRECAUTIONS

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Sam pler: W ash ‘n Dri or ASTM equivalent[2] [pre-pac kaged m oist dispos able towe lette (wipe )]. Inductively coupled plasma-atomic emission spectrometer, equipped as specified by the manufacturer for analysis of elements of interest. Regulator, two-stage for argon. Beakers, Phillips, 125-mL, or Griffin, 50-mL, with watch glass c overs .** Volum etric flasks, 10- and 100-m L.** Ass orted vo lum etric pipettes as nee ded.** Hotplate, surface temperature 150oC. Polystyrene centrifuge tubes, 50-mL and 15-mL. Hard-w alled sam ple container. and rinse thorough ly in de-ionized water.
 * Clean all glasswa re with conc. nitric acid

SPECIAL PRECAUTIONS: Nitric and perchloric acids are strong oxidizers and extremely corrosive. Perform all perchloric acid digestions in a perchloric acid hood. When working with acids use gloves and avoid inhalation or contact with skin or clothing.

SAMPLING:[3] 1. W earing a clean pair of powder-less, plastic gloves, place the template over the area to be sampled and secure it. If the area to be sampled is in a confined area and a template cannot be used, measure the sampling area, and delineate the area to be sampled with mask ing tape. 2. Re m ove a wipe from its pac kage, and u nfold it. 3. W ipe the surface to be sam pled using fingertips held tog ethe r and app lying firm pres sure. Us e an overlapping ‘S’ pattern to cover the entire surface with horizontal strokes. 4. Fold the exposed side of the wipe in, and wipe the same area using vertical ‘S’-strokes. 5. Fo ld the wipe again to reveal an unexposed surface, and wipe the surface a third tim e as described in step 3. 6. Fold the wipe, expos ed side in, and place it into a clean hard-wa lled sam ple container (e.g., 50-mL centrifuge tube). Seal securely and label the sam ple container. NOTE: Com positin g of wipe sam ples is not recom m ended, because (a) they cause sam ple prep aration an d an alytical difficu lties, and (b) site-specific a nalytical info rm ation is lost. 7. Clean the tem plate in pre paration for the next w ipe sam ple using water or a wipe. A disposable template may also be used. 8. Rem ove gloves and discard. Clean gloves should be worn for each new sample. 9. Field blanks: 10% of samples, at least three per batch. Remove unexposed wipes from packaging and place into sample containers. The field blanks should be collected at the beginning, middle, and end of sampling.

SAMPLE PREPARATION: 10. Transfer the samples and blanks to clean beakers. 11. Add 20 mL concentrated nitric acid and 1 mL concentrated perchloric acid. Cover beaker with a watchglass. Let stand 30 min at room tem perature. Start a reagent blank at this step. 12. Allow samples to heat for approximately 8 hours @150 °C. 13. Rem ove watchg lass and rinse into the beake r with de-ionized water. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition