Soil digestion method:
Weigh 0.2g (precisely 0.1mg) sample into a 50ml PTFE digestion tube, add 5ml hydrochloric acid, heat digestion at 150℃ for 30min on a graphite digestion instrument in a fume hood, add 5ml nitric acid, continue heating digestion at 150℃ for 30min , Add 4ml of hydrofluoric acid, continue heating at 150°C for 30min, then increase the temperature to 170°C, cover and digest for 120min, and finally add 1ml perchloric acid, open the lid and heat at 170°C for 60min.
AUWII digestor: The entire process of digestion and acid removal takes only 4.5 hours
Microwave digestion: digestion for 50 minutes, cooling to room temperature for 60 minutes, and acid removal for 180 minutes, 4.8 hours;