FIGURE 3.11 Acid digestion procedure. 3.3.1 Chemical Matrix Digestion Method Equipment needed for this procedure(Figure 3.11)includes: 1.Fume hood with a vacuum system 2.Large flask which can be attached to the vacuum system 3.Buchner funnel with filter 4.A 400-ml beaker 5.Nitric acid 6.Glass stirring rod 7.Bunsen burner or electric heater 8.Desiccator 9.Precision balance 10.Rubber gloves and goggles 3.3.1.1 Procedure 1.Take a 50 x 50 mm composite sample and weigh it.Also weigh the dry Buchner funnel with the filter. 2.Put on rubber gloves and goggles and activate a hood vent fan. Place the sample in the 400-ml beaker and pour in 200 ml of the nitric acid(use the glass stirring rod for controlled,slow pouring of the acid).Heat the beaker with the Bunsen burner until the acid fumes,but avoid boiling;stir occasionally.Continue heating until the matrix is dissolved and the sample disintegrates,leaving bare fibers. ©2003 by CRC Press LLC3.3.1 Chemical Matrix Digestion Method Equipment needed for this procedure (Figure 3.11) includes: 1. Fume hood with a vacuum system 2. Large flask which can be attached to the vacuum system 3. Buchner funnel with filter 4. A 400-ml beaker 5. Nitric acid 6. Glass stirring rod 7. Bunsen burner or electric heater 8. Desiccator 9. Precision balance 10. Rubber gloves and goggles 3.3.1.1 Procedure 1. Take a 50 × 50 mm composite sample and weigh it. Also weigh the dry Buchner funnel with the filter. 2. Put on rubber gloves and goggles and activate a hood vent fan. Place the sample in the 400-ml beaker and pour in 200 ml of the nitric acid (use the glass stirring rod for controlled, slow pouring of the acid). Heat the beaker with the Bunsen burner until the acid fumes, but avoid boiling; stir occasionally. Continue heating until the matrix is dissolved and the sample disintegrates, leaving bare fibers. FIGURE 3.11 Acid digestion procedure. TX001_ch03_Frame Page 50 Saturday, September 21, 2002 4:51 AM © 2003 by CRC Press LLC