Page:NIOSH Manual of Analytical Methods - 9102.pdf/3

 ELEM ENT S O N W IPES: M ETH OD 9102, Issue 1, dated 1 5 Ma rch 2003 - Page 3 of 5 14. Continue to heat on h otplate (120 °C). NOTE: Som e species will not be completely solubilized by this procedure. Alternative solubilization techniques for most of these elements can be found elsewhere. 15. Add additional amounts of HNO 3, if necessary, until th e solution is clear an d the wipe m edia is completely destroyed. 16. Tak e the sam ple to near dryness (ca. 0.5 m L). 17. Dissolve the residue in 0.5 mL dilution acid. 18. Transfer the solutions quantitatively to 15-mL centrifuge tubes or 10 mL volumetric flasks. 19. Dilute to 10 mL w ith de-ionized water.

CALIBRATION AND QUALITY CONTRO L: 20. Calibrate the spectrometer according to the manufacturers recomm endations. NOTE: Typically, an acid blank and 10 µg/mL m ulti-element working standards are used. The following m ulti-elem ent co m binatio ns are chem ically and spectrally com patible in 4% HNO 3 /1% HC lO 4: a. Al, As, Ba, Be, Cd, Ca, Cr, Co, Cu, In, Fe, La; b. Pb, Li, Mg, Mn, Ni, P, K, Sc, Se, Ag, Sr, Tl, V, Y, Zn; c. Sb, Mo, Te Sn, T i, W , Zr; d. Pt 21. Analyze a standard for every six samples. 22. Check recoveries with at least two spiked media blanks per ten samples.

MEASUREMENT: 23. Set spec trome ter to conditions spe cified by manufac turer. 24. Analyze standards and samples. NOTE: If the va lues for the sam ples are a bove the rang e of the standa rds, dilute the solutions w ith dilution acid, re-analyze and apply the appropriate dilution factor in the calculations.

CALCULATIONS: 25. Ob tain the solution co nce ntration s for the sam ple, C s (µg/m L), an d the average m edia blank, C b (µg/m L), from the ins trum ent. 26. Us ing the solution volum es o f sam ple, V s (m L), an d m edia blank, V b (mL), calculate the concentration, C (µg/cm 2), of each element on the surface area sampled, S (cm 2):

EVALUATION OF METHOD: This method was evaluated using wipe media spiked with aqueous standards (fortified samples) and wipe m edia spiked with SRM 2711 (Montana Soil). Recoveries for the twenty-three elements listed on page 920 1-1 were within the range of 75-115% for the fortified samples. Ten of the eleme nts found in SR M 27 11 were recoverable within the same range. Th ese are: silver, arsenic, ca dm ium, co balt, co pper, m anganese, nicke l, pho sph orus , lead, and zinc.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition