4 mL wine and 3 mL nitric acid (65%,Suprapur, subboiled) were mixed in a 70 mL quartz tube.
After
closing, the tube was heated under pressure with the following
temperature program: from 25°C to 100°C 15 min; at 100°C 30
min; from 100°C to 300°C 15 min; at 300°C 60 min; cooling