Page:NIOSH Manual of Analytical Methods - 7704.pdf/3

 BERYLLIUM in Air: METHOD 7704, Issue 1 dated 06 April 2007 – Page � of 6 5.	Place each tube into a mechanical rotator, and rotate for at least 30 min. NOTE: Rotator may also be substituted by a shaker or an agitator as long as the dissolution solution wets the filter well. Sonication has also been shown to be effective. For dissolution of refractory materials such as high-fired beryllium oxide, agitation of the dissolution solution with the media must be replaced by heating to 80 °C for 30 minutes. Any standard dissolution process is particle-size dependent. The two sources of BeO used to validate the method are described in the backup data report [6]. 6.	Filter each solution with a nylon syringe filter into a clean tube. NOTE: This tube should be able to accept a cap so that the solution may be saved and used later for reanalysis if required. 7.	Pipet 0.1 mL of each sample filtrate into cuvettes containing 1.9 mL of the detection solution. Cap and mix briefly. NOTE:	The above procedure is typically used to analyze a range of 0.05 µg to 4 µg of beryllium on the sampling media. Alternative ratios of dissolution solution and detection solution may be used for analyzing alternative ranges of beryllium concentration. To test a range of 0.005 µg to 0.4 µg of beryllium on the sampling media, 0.4 mL of the sample filtrate is added to 1.6 mL of the detection solution in the cuvettes. NOTE:	If high iron or titanium concentration is suspected or is evident (owing to the appearance of suspended precipitate), allow the solution to settle and filter the solution using a nylon syringe filter. NOTE:	The stability of the detection and the dissolution solution is more than one year and of the mixed measurement solution comprising both is greater than 30 days. The solutions must be kept in sealed containers, and the detection and mixed solutions must be stored away from light. CALIBRATION AND QUALITY CONTROL: 8.	Calibrate the fluorometer with beryllium stock standard solutions. Prepare a calibration graph of fluorescence intensity vs. beryllium concentration (ng/mL) in the stock standard. NOTE:	To test a range of 0.05 µg to 4 µg of beryllium on the sampling media, beryllium stock standard solutions are made up using beryllium spectrometric standards diluted with the ammonium bifluoride dissolution solution. A recommended series of stock standard solutions is (800, 200, 40, 10, and 0) ng/mL. As with the samples, the stock standards are prepared for analysis by adding 0.1 mL of beryllium stock standard into 1.9 mL of detection solution (20-fold dilution). Please see Table 1. NOTE:	To test a range of 0.005 µg to 0.4 µg of beryllium on the sampling media, a recommended series of stock standard solutions is (80, 20, 4, 1, and 0) ng/mL. These standards with lower beryllium concentration can be prepared by 10-fold dilution of the stock standards mentioned in the note above. As with the samples, these stock standards are prepared for analysis by adding 0.4 mL of beryllium stock standard into 1.6 mL of detection solution (5-fold dilution). Please see Table 2. NOTE:	If alternative ratios of dissolution solution and detection solution are used for sample preparation, then a similar ratio for calibration is required. 9.	Analyze a stock standard, a reagent blank, and a media blank at least once every 20 samples. Ensure that the concentration range of the stock standards spans the beryllium levels found in the samples. 10.	Analyze one media spike and one quality control blind spike per 20 samples (minimum of three each per sample set) to insure that percent recovery is in control (e.g., 100 ± 15). Correct sample results for the average recovery if it differs significantly from 100 %. NOTE:	If it is suspected that beryllium oxide may be present, then it is recommended to use beryllium oxide for media and blind spikes. NIOSH Manual of Analytical Methods (NMAM), 5th Edition (Electronic)

Updated: 04/06/2007