National Institute for Occupational Safety and Health

“ NIOSH Manual of Analytical Methods (NMAM) , Fifth Edition ELEMENTS by ICP (Microwave Digestion) : METHOD 7302, Issue 1, dated 21 July 2014 - Page 3 of 9
NOTE:
In order to avoid a violent exothermic reaction, do not add water to concentrated nitric acid. Acid should be added after the water has been placed in the vessel. 5.
Place digestion vessels in microwave, and run the preprogrammed digestion procedure for 12vessel digestion: 1200 W power, ramp to 150 °C over 20 min, hold for 10 min at 215 °C followed by at least a 5 min cool down (power will be adjusted lower for fewer vessels) . 6. ”

“ Sample at an accurately known flow rate between 1 and 4 L/min. For estimated sampling volumes see Table 1. For TWA measurements see Table 2. Do not exceed a filter loading of approximately 2 mg total dust. NOTE: Filter overloading can be assessed by periodic visual checks. See NMAM Chapter O, “Factors Affecting Aerosol Sampling,” for additional discussion on filter capacity. [1] SAMPLE PREPARATION NOTE:
If total weights are desired, weighing should be done at this step. Follow NIOSH method 0500 for gravimetric analysis [11] . 3. ”

“ Submit extracted and diluted samples for analysis. CALIBRATION AND QUALITY CONTROL 10.
Calibrate the spectrometer according to the manufacturer recommendations. NOTE:
Typically an acid blank and multi-element working standards are used. The following multi element combinations are chemically compatible in 20% HNO3. a. Al, As, Ba, Be, Ca, Co, Cr, Cu, Fe, Li, Mg, Mn, Mo, Na, Ni, Pb, Se, Sr, Ti, V, Y, Zn, Zr; b. B, K, P, Sn, Te, Tl; c. Ag, Cd, Sb; d. Pt. 11.
Analyze all applicable standards at least once every twenty (20) analyses (minimum frequency 5%) . 12. ”

“ Elements by ICP using microwave digestion, NMAM 7302, Issue 1, Backup data report. Cincinnati OH: Datachem Laboratory developed under contract CDC200-2001-08000. Unpublished. [9] Lide DR, ed. [1994] Handbook of chemistry and physics. 74th ed. Baca Raton, FL.: CRC Press. [10] Butler OT, Howe AM [1999] . Development of an international standard for the determination of metals and metalloids in workplace air using ICP-AES: Evaluation of sample dissolution procedures through an interlaboratory trial. J. Environ. Monit. ”