a household microwave oven is adequate for this experiment,and the high cost of a commercial microwave oven is not justified for 2-3 weeks of use each year. to prevent corrosive fumes from entering the oven chamber and possibly the electronics, samples were digested in 250-mL high-density polyethylene(HDPE)containers with screw caps.A 1/4-in.hole was drilled in the lid of the container and a fitting with 1/8-in.HDPE tubingg was screwed into it . the tubing vented any volatile or corrosive gases (e.g.,HCl)from the individual containers, allowing the digestion of sample to be carried out at atmospheric pressure.venting was achieved by threading the HDPE tubing through ventilation holes inside the oven chamber and out through the bottom of the microwave oven as illustrated in figure 1.