Page:NIOSH Manual of Analytical Methods - 7301.pdf/2

 ELEM ENT S by ICP (Aqu a Reg ia Ashing): MET HO D 730 1, Issue 1, dated 15 M arch 200 3 - Page 2 o f 8 REAGENTS:

EQUIPMENT:

1. Nitric acid (HNO 3), conc.*, ultra pure. 2. Hydrochloric acid (HCl), conc.*, ultra pure. 3. Ashing acid (Aqua Regia): 1:3 (v/v) HNO 3:HC l. Mix 1 volume conc. HNO 3 with 3 volumes conc. HCl. 4. Ca libration s tock solutions, 1000 µg/m L. Com mercially available, or prepared per instrument manufacturer's recomm endation (see step 12 ). 5. Dilution acid, 1% HNO 3, 3% HCl. Add 50 mL ashing acid to 600 mL water; dilute to 1 L. 6. Argon. 7. Distilled,deionized water.

1. Sam pler: cellulose ester m em brane filter, 0.8-µm pore size; or polyvinyl chloride (PVC) m em brane, 5.0-µm pore size; 37-m m diam eter, in cassette filter holder. 2. Personal sa m pling pum p, 1 to 4 L/m in, with flexible connecting tubing. 3. Inductively coupled plasma-atomic emission spectrometer, equipped as specified by the manufacturer for analysis of elements of interest. 4. Regulator, two-stage, for argon. 5. Beakers, Phillips, 125-mL, or Griffin, 50-mL, with watch glass c overs .** 6. Volum etric flasks, 10-, 25-,10 0-m L., and 1-L ** 7. Ass orted vo lum etric pipets as need ed.** 8. Hotplate, surface temperature 150 °C.



See SPECIAL PRECAUTIONS.



Clean all glasswa re with conc. nitric acid and rinse thoroughly in distilled water before use.

SPECIAL PRECAUTIONS: Conce ntrate d ac ids are po werful oxidizers, toxic, an d co rrosive liquids. W ear protective clothing and work in a fume hood.

SAMPLING: 1. Calibrate each personal sampling pump with a representative sampler in line. 2. Sam ple at a n ac curately kn own flow ra te betwee n 1 and 4 L/m in for a total sam ple size of 200 to 2000 L (see Table 1) for TW A measurem ents. Do not exceed a filter loading of approximately 2 mg total dust.

SAMPLE PREPARATION: 3. Open the cassette filter holders and transfer the samples and blanks to clean beakers. 4. Add 5 mL ashing acid. Cover with a watchglass. Let stand 30 min at room tem perature. NOTE: Start a reagent blank at this step. 5. Heat on hotplate (120 °C) until ca. 0.5 mL remains. NOT E 1: Reco very of lead from some paint matrices may require other digestion tech niqu es. See Method 7082 (Lead by Flame AA S) for an alternative hotplate digestion procedure or Method 730 2 for a m icrow ave diges tion pro ced ure. NOTE 2: So m e species of Al, Be, Co, C r, Li, Mo, S b, W , and Z r will not be com pletely solubilized by this procedure. Alternative solubilization techniques for m ost of these elements can be found elsewhe re [5-1 0]. 6. Add 2 m L ashing acid and repeat step 5. Rep eat this step until the solution is clear. NOT E: PVC filters will not completely dissolve after repeated additions of ashing acid. 7. Rem ove watchg lass and rinse into the beake r with distilled water. 8. Increase the tem perature to 150 °C and take the s am ple to near dryness (ca. 0.5 m L). 9. Dissolve the residue in 2 to 3 mL dilution acid. 10. Transfer the solutions quantitatively to 25-mL volumetric flasks. 11. Dilute to volume with dilution acid.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition