The invention belongs to the field of
chemistry, and particularly relates to a method suitable for measuring 16 elements including lead,
copper, iron, arsenicum,
chromium,
zinc,
cadmium,
manganese,
nickel,
cobalt,
indium,
rhodium,
gallium,
bismuth,
neodymium and
cerium in a
food additive citric acid. The measuring method consists of the following steps: firstly, weighing a sample of the
food additive citric acid, and putting the sample in a
microwave digestion instrument; secondly, performing sample
digestion by using a mixed acid of
nitric acid and
perchloric acid; thirdly, adding a sample solution into hyperpure water according to a proportion that 1 to 2 mL of the
nitric acid is added into each 10 grams of the
citric acid sample, and moving the mixture into a plastic
volumetric flask of100 mL; fourthly, drawing calibration curves: using
national standard stock solutions (GBW) containing the 16 elements, using 3 percent
nitric acid to dilute the
national standard stock solutions into mixed standard solutions with the concentrations of 0.0, 5.0, 10.0, 20.0, 30.0, 40.0 and 50.0 umg / L, and drawing the calibration curves of each elements by using the concentrations as horizontal coordinates and
ion abundances as vertical coordinates; and fifth, measuring and calculating the contents of the 16 elements in the
food additive citric acid in the sample solution obtained in the thirdstep according to the fourth step.