I believe that using either 6 N HCl or 2-4 N H2SO4 for acid digestion at elevated temperatures around 110 degrees Celsius for a duration of 12 to 16 hours should be effective. Which digestion tubes from Kimble or other reputable companies suit this process? Are glass tubes available to withstand high pressures and be vacuum-sealed for continuous digestion? Your practical experience and suggestions would be greatly appreciated. Please advise.