Page:NIOSH Manual of Analytical Methods - 7303.pdf/2

 ELEMENTS by ICP (Hot Block/HCl/HNO3 Ashing): METHOD 7303, Issue 1, dated 15 March 2003 - Page 2 of 6 EQUIPMENT:

REAGENTS: 1. Hydrochloric acid,* conc., ultra pure. 2. Nitric acid,* conc., ultra pure. 3. Calibration stock solutions, 50-1000 :g/mL. Com mercially available single element solutions or multielement solutions prepared as instructed by the instrumen t man ufacturer. 4. Argon, prepurified. 5. Distilled, deionized, Type II water. 6. Diluting solution: 5% HCl : 5% HNO 3. To about 600 m L of deionized water in a 1-L volumetric flask, slowly add 50 mL conc. HCl and 50 m L conc. H NO 3. Dilute to the m ark with deionized water.

1. Sam pler: cellulose ester mem brane filter, 0.8:m pore size, 37 -m m diam eter; in c ass ette filter holder. 2. Personal sa m pling pum p, 1 to 4 L/m in, with flexible connecting tubing. 3. Ind uctively coupled arg on plasm a-ato m ic emission spectrometer, equipped as specified by the m anu facturer for an alysis of elem ents of interest. 4. Hot block apparatus at 95 / C. 5. Digestion vessels and caps, 50-mL. 6. W atchglasses. 7. Pip ette s, e lectronic and m echanical. 8. Regulator, two-stage, for argon. 9. Forceps.

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.
 * See SPECIAL PRECAUTIONS

SAMPLING: 1. Calibrate each personal sampling pump with a representative sampler in line. 2. Sa m ple at an acc urate ly kn ow n flo w rate betwe en 1 and 4 L/m in for a to tal sam ple size of 20 0 to 2000 L for T W A m eas urem ents. Do not exce ed a filter loading of a ppro xim ately 2 m g total dust.

SAMPLE PREPARATION: 3. Open the cassette filter holder and with forceps remove the sample filter. Fold the filter into quarters taking care not to lose any sample, and transfer to a clean, 50-mL hot block digestion tube. 4. Add 1.25 mL HCl. Cover with a plastic watchglass. Place in the hot block and heat at an internal temperature of 95 / C for 15 minutes. NOTE: The internal temperature may vary from the digital readout. Calibrate th e ho t block prior to digestion. 5. Rem ove the sample from the hot block and cool for 5 minutes. Remove watchglass and add 1.25 mL HNO 3. Replace watchglass and return to hot block at 95 / C for 15 minutes. 6. Rem ove the sample from the hot block and coo l for at least 5 m inutes. Rinse wa tchg lass into the sam ple container and discard watchglass. 7. Dilute to 25-mL final volum e with distilled, deionized Type II water.

CALIBRATION AND QUALITY CONTRO L: 8. Ca librate the spec trom eter a cco rding to the manufacturer's recomm endations. Use standards consisting of the same 5% HCl : 5% HNO 3 matrix as the samples. 9. Analyze a standard every 10 samples. 10. Analyze a media blank every 20 samples, and a reagent blank every 10 samples. 11. Analyze a set of two laboratory control samples every 40 samples of a given matrix for a given analyte. 12. Check recoveries with at least two spiked media blanks per ten samples. NOTE: In the determination of lead, there may be a measurem ent interference (for example, samples with high alum inum levels). More recen t instrum ents have a correction for this.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition