Page:NIOSH Manual of Analytical Methods - 7704.pdf/4

 BERYLLIUM in Air: METHOD 7704, Issue 1, dated 06 April 2007 – Page � of 6 MEASUREMENT: 11.	For each sample, obtain the fluorescence intensity at λmax or with optical filter for appropriate wavelength. 12.	If the fluorescence response for any of the samples is above the range of responses for the stock standards, dilute the sample filtrate with dissolution solution, reanalyze, and apply the appropriate dilution factor (D) in subsequent calculations. CALCULATIONS: 13.	Obtain the solution concentration for each sample filtrate, Cs (ng/mL), and the average media blank, Cb (ng/mL) from the calibration graph. 14.	Using the dissolution volumes (normally 5 mL) of sample, Vs (mL), and media blank, Vb (mL), calculate the concentration, C (µg/m3), of Be in the air volume sampled, V (L), while accounting for the dilution factor (D). [C V − C V ] C = D × s s b b, ng/L or µg/m3. V NOTE:	Tables 1 and 2 can be used for correlating the amount of beryllium in the sampling media with the concentrations of beryllium in solution. Table 1 is for testing media with 0.2 µg to 4 µg of beryllium at 20-fold dilution and Table 2 is for testing media with 0.02 µg to 0.4 µg of beryllium at 5-fold dilution. Table 1. Correlation of amount of Be in sampling media with Be concentration in stock standard and Be concentration as analyzed, assuming 0.1 mL of sample or stock standard is added to 1.9 mL of detection solution (20-fold dilution). Be concentration in stock standard (ng/mL)

Be concentration as analyzed (ng/mL)

Amount of Be in the media* (ng)

0 10 40 200 800

0 0.5 2 10 40

0 50 200 1000 4000


 * Equals stock standard Be concentration (ng/mL) × volume (5 mL) of dissolution solution used to extract media.

Table 2. Correlation of amount of Be in sampling media with Be concentration in stock standard and Be concentration as analyzed, assuming 0.4 mL of sample or stock standard is added to 1.6 mL of detection solution (5-fold dilution). Be concentration in stock standard (ng/mL)

Be concentration as analyzed (ng/mL)

Amount of Be in the media* (ng)

0 1 4 20 80

0 0.2 1 4 16

0 5 20 100 400

Updated: 04/06/2007
 * Equals stock standard Be concentration (ng/mL) × volume (5 mL) of dissolution solution used to extract media.

NIOSH Manual of Analytical Methods (NMAM), 5th Edition (Electronic)