Page:NIOSH Manual of Analytical Methods - 8005.pdf/3

 ELEMENTS in blood or tissue: METHOD 8005, Issue 2, dated 15 August 1994 - Page 3 of 6 2.

Ship samples in dry ice and store frozen (<15 °C) prior to digestion.

SAMPLE PREPARATION: 3. 4. 5.

6. 7. 8.

Allow sample to equilibrate to room temperature. Transfer accurately weighed portions of 10 g blood, 0.25 g "dry" tissue, or 1.0 g "wet" tissue to a beaker. Add 10.0 mL digestion acid to each blood sample or 5.0 mL digestion acid to each tissue sample. Heat at 110 °C for 2 h. NOTE: Start reagent blanks, in triplicate, at this step. Increase hotplate temperature to 250 °C and heat until ca. 1 mL (for blood) or ca. 0.5 mL (for tissue) remains (2 to 3 h). Allow beaker to cool. Choose one of the following: a. External standard method. Transfer contents of beaker to a volumetric flask (10 mL for blood; 5 mL for tissue). Dilute to the mark with deionized water. b. Internal standard method. Add, via pipet, 10.0 mL (for blood) or 5.0 mL (for tissue) yttrium standard to the beaker.

CALIBRATION AND QUALITY CONTROL: 9. 10. 11.

Calibrate the spectrometer according to manufacturer's recommendations. NOTE: Typically, an acid blank and 10 µg/mL multielement solutions are used. Analyze a standard for every ten samples. Check measurement recoveries for all elements of interest with at least three spiked, unexposed samples or with reference materials of known elemental composition. These quality control samples should constitute 15 to 20% of all samples analyzed. NOTE: For blood or tissue spikes, split a control sample and spike one fraction. Subtract the element quantity found in the unspiked portion from the element quantity found in the spiked portion and determine measurement recovery. Correct all samples for this measurement recovery. This is especially important for blood samples because routine interelement corrections will not adequately compensate for the high levels of iron present, which has numerous spectral emission wavelengths.

MEASUREMENT: 12. 13.

Set the spectrometer to conditions specified by the manufacturer. Analyze standards and samples. NOTE: If the values for the samples are above the range of the standards, dilute the sample solutions with 10% H 2SO 4, reanalyze, and apply the appropriate dilution factor in calculations.

CALCULATIONS: 14. 15.

Obtain the solution concentration found for each element in the sample, C s (µg/mL), and the average blank, C b (µg/mL), from the measurement data. According to the method of standardization, calculate the concentration, C (µg/g), of each element in the mass of sample taken, M (g). a. External standard method. Use the final solution volumes of sample, V s (mL) and blank, Vb (mL): b. Internal standard method. Use the yttrium standard concentration, C y (µg/mL), the volume of yttrium standard added, V y (mL), and the concentration of yttrium found in the NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94