Abstract:
A method for determination of 15 metal elements, including beryllium, boron, manganese, copper, zinc, arsenic, selenium, strontium, molybdenum, cadmium, tin, antimony, barium, mercury, and lead in American ginseng by inductively coupled plasma mass spectrometry (ICP-MS) with rapid digestion was proposed. 0.2 g of crushed and sieved American ginseng sample was taken and placed in a 50 mL-centrifuge tube. 2 mL of 30% (mass fraction) hydrogen peroxide solution and 5 mL of nitric acid were added and the mixture was sealed overnight. Then the mixture was placed in a graphite digestion apparatus at 110 ℃ for 60 min and cooled to 25 ℃. 200 μL of 1 mg·L
-1 gold standard solution was added, and the solution was made its volume up to 50 mL with water and mixed well. The solution was centrifuged for 10 min, and the supernatant solution was passed through a 0.45 μm water phase filter membrane. 15 metal elements in the filtrate were determined by ICP-MS, and 20 μg·L
-1 internal solution, including scandium, germanium, indium, and bismuth, was added online. As shown by the results, linear relationships between the ratios of the corresponding signal intensities after internal standard correction and mass concentrations of 15 metal elements were found in definite ranges, with detection limits (3
s) in the range of 0.002-0.282 mg·kg
-1. This method was used to analyze the standard substance, and the determined values of 15 metal elements were found within the uncertainty range of the certified values. Test for recovery was made by the standard addition method, giving results in the range of 89.1%-103%, with RSDs (
n=6) of the determined values less than 6.0%. The rapid digestion method and microwave digestion method were used to digest the American ginseng samples, and the determined values of various metal elements were basically consistent.