Determination of 9 Metal Elements in Traditional Handmade Paper by ICP-AES and Their Traceability Study

The paper sample was cut to pieces with size smaller than 4 mm×4 mm, and the bamboo or bamboo pulp raw material samples (bamboo pulp sample was squeezed out moisture) were cut to scraps with size smaller than 4 mm×4 mm×4 mm. The samples (0.500 0 g) was taken in a Teflon digestion tank, then 4 mL of nitric acid and 2 mL of hydrogen peroxide were added successively. For paper sample, 2 mL of water was added. After standing for 15 minutes, microwave digestion was carried out. After digestion, the solution was heated at 135℃ for 30 min to remove the remaining nitric acid and then cooled. If the sample digestion was incomplete, 4 mL of nitric acid and 0.5 mL of hydrofluoric acid were added, and the above digestion process was repeated. The digestion solution was filtered and the filter was diluted with water and made up to 50.0 mL. Inductively coupled plasma atomic emission spectrometry was used to determination of potassium, calcium, sodium, magnesium, copper, aluminum, iron, zinc and strontium in the solution. The results show that linear relationships were found between emission intensity and mass concentration of the 9 metal elements within definite ranges, and the detection limits were between 1.0 and 2.0 mg·kg^-1. Test for recovery was made by standard additon method to samples, giving values of recovery between 81.3% and 114%. The relative standard deviations of the measured values (n=7) were between 1.2% and 6.6%. The method was used to trace the metal elements affecting the quality of handmade paper in the materials of 7 main process for making handmade paper, and 9 metal elements in 6 typical samples were determined.<