Page:NIOSH Manual of Analytical Methods - 7306.pdf/3

 ELEMENTS by Cellulosic Internal Capsule Sampler: METHOD 7306, Issue 1, dated 10 September 2015 - Page 3 of 11

4.	 Carry out sample dissolution in accordance with one of the sample preparation procedures described in NIOSH 7300, 7301, 7302, or 7303 [6-9]. NOTE: The dissolution acid level within the vessel should cover the internal capsule. 5.	 After allowing to cool to room temperature, transfer the solutions quantitatively to 25-mL volumetric flasks. 6.	 Dilute to volume. NOTE: If greater sensitivity is required, the final sample volume may be held to 10 mL. CALIBRATION AND QUALITY CONTROL: 7.	 Calibrate the spectrometer according to the manufacturer recommendations. NOTE: Typically, an acid blank and 1.0 μg/mL multielement calibration standards are used. The following multielement combinations are chemically compatible in 5% HNO3: a.	 Al, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, La, In, Na b.	 Ag, K, Li, Mg, Mn, Ni, P, Pb, Se, Sr, Tl, V, Y, Zn, Sc c.	 Mo, Sb, Sn, Te, Ti, W, Zr 8.	 Analyze at least one calibration standard per ten samples. 9.	 Check recoveries with at least one media blank and two spiked media blanks per twenty samples. Media should be spiked with analytes of interest. NOTE: Whenever possible, QA/QC samples should be prepared from certified reference materials in a matrix similar to the bulk material sampled. Liquid spiked filters are only surrogates for real world samples and QC data based upon certified samples are preferred. MEASUREMENT: 10.	 Set ICP-AES spectrometer to conditions specified by manufacturer. 11.	 Analyze standards and samples by ICP-AES in accordance with manufacturer recommendations. NOTE:	If the values for the samples are above the range of the standards, dilute the solutions (ensuring 	the samples remain acid matrix-matched to the calibration standards), reanalyze and apply the appropriate dilution factor in the calculations. CALCULATIONS: 12.	 Obtain the solution concentrations for the sample, Cs (μg/mL), and the average media blank , Cb (μg/mL), from the instrument. 13.	 Using the solution volumes of sample, Vs (mL), and media blank, Vb (mL), calculate the concentration, C mg/m3), of each element in the air volume sampled, V (L):

C=

(Cs Vs )-(Cb Vb ) V

, mg/m3

NOTE: μg/L Ξ mg/m3 EVALUATION OF METHOD: A previous interlaboratory investigation of aerosol-loaded cellulosic capsules (provided by SKC, Inc., EightyFour, PA) provided the background information for the development of this method [14]. That investigation yielded data for Cd, Cr, Co, Cu, Fe, Mn, Ni and Pb [14]. Recoveries for these elements were quantitative and values of overall relative standard deviation were <0.20 [14], which compare favorably with the variability typically observed in interlaboratory multielement analysis of air samples [15,16]. To obtain performance data for additional elements, interlaboratory performance data were obtained using 37-mm diameter cellulose acetate internal capsules attached to mixed-cellulose ester filters (Solu-sert™ from NIOSH Manual of Analytical Methods (NMAM), Fifth Edition